“The gut microbiome has transformed our understanding of human health,” says Tim Spector, PhD, co-founder of the Zoe Nutrition App from King’s College London. “We now recognize that microbes play a crucial role in metabolism, immunity, and mental health.”
Although significant advancements in microbiome research have surged in the past 25 years, humans have a long history of utilizing microorganisms to enhance health. The Romans, for instance, employed bacterial-based treatments to “guard the stomach” without comprehending their biological mechanisms.
In the 17th century, microbiologist Antony van Leeuwenhoek made the groundbreaking observation of the parasite Giardia in his own stool. It took scientists another two centuries to confirm his discoveries, until the 21st century when the profound impact of gut and skin microbes on health became evident.
By the 1970s, researchers determined that gut bacteria could influence the breakdown of medications, potentially modifying their efficacy. Fecal transplant studies hinted at how microbial communities could restore health. However, it was the rapid advancements in gene sequencing and computing in the 2000s that truly revolutionized this field. Early genome sequencing revealed every individual possesses a distinct microbial “fingerprint” of viruses, fungi, and archaea.
In the early 2000s, groundbreaking studies illustrated that the microbiome and immune system engage in direct communication. This collaboration reshapes the microbiome’s role as a dynamic participant in our health, impacting a wide range of systems, from the pancreas to the brain.
Exciting findings continue to emerge; fecal transplants are proving effective against Clostridium difficile infections, while microorganisms from obese mice can induce weight gain in lean mice. Some bacterial communities have shown potential to reverse autism-like symptoms in mice. Recently, researchers have even suggested that microbial imbalances could trigger diabetes and Parkinson’s disease. “Recent insights into the human microbiome indicate its influence extends far beyond the gut,” states Lindsay Hall from the University of Birmingham, UK.
Researchers are gaining a clearer understanding of how microbial diversity is essential for health and how fostering it may aid in treating conditions like irritable bowel syndrome, depression, and even certain cancers. Studies are also investigating strategies to cultivate a healthy microbiome from early life, which Hall believes can have “profound and lasting effects on health.”
In just a few decades, the microbiome has evolved from an obscure concept to a pivotal consideration in every medical field. We are now entering an era that demands rigorous testing to differentiate effective interventions from overhyped products, all while shaping our approach to diagnosing, preventing, and treating diseases.
Oral Bacteria (Blue) on Human Cheek Cells (Yellow) in Scanning Electron Micrograph
Steve Gschmeisner/Science Photo Library
Recent research has revealed that individuals with obesity exhibit unique oral microbiome characteristics. This finding could pave the way for early detection and prevention strategies for obesity.
“Given that the oral microbiome is the second largest microbial ecosystem in the human body, we aimed to investigate its association with systemic diseases,” says Ashish Jha, from New York University, Abu Dhabi.
Jha and his team analyzed saliva samples from 628 adults in the United Arab Emirates, 97 of whom were classified as obese. They compared these samples with a control group of 95 individuals of healthy weight, similar in age, gender, lifestyle, oral health, and tooth brushing habits.
The analysis showed that the oral microbiome of obese individuals has a higher abundance of inflammation-causing bacteria, such as Streptococcus parasanguinis and Actinobacterium oris. Additionally, Oribacterium sinus produces lactic acid, which is linked to poor metabolic health.
Jha and his colleagues identified 94 distinct differences in metabolic pathways between the two groups. Obese participants demonstrated enhanced mechanisms for carbohydrate metabolism and the breakdown of histidine, while their capability to produce B vitamins and heme—crucial for oxygen transport—was reduced.
Metabolites notably generated in obese individuals include lactate, histidine derivatives, choline, uridine, and uracil, which are associated with metabolic dysfunction indicators such as elevated triglycerides, liver enzymes, and blood glucose levels.
“When we analyze these findings collectively, a metabolic pattern surfaces. Our data indicates that the oral environment in obesity is characterized by low pH, high carbohydrate levels, and pro-inflammatory conditions,” notes Lindsey Edwards from King’s College London. “This study offers compelling evidence that the oral microbiome may reflect and contribute to the metabolic changes associated with obesity.”
Currently, these findings suggest a correlation rather than causation. “While some associations are surprising, we cannot determine cause and effect as of now, which remains our next focus,” Jha states.
To explore whether the oral microbiome contributes to obesity or is modified by it, Jha and his team plan further experiments analyzing both saliva and gut microbiomes to investigate potential microbial and metabolic transfers.
Professor Jha believes this is plausible, as the mouth’s extensive blood vessel network facilitates nutrient absorption and taste sensing, potentially allowing metabolites direct access to the bloodstream, influencing other bodily systems.
Establishing a causal connection will also necessitate randomized controlled trials and detailed metabolic pathway analyses, according to Edwards.
As dietary patterns evolve, specific food components may become more readily metabolized by certain bacteria, leading to increased microbial activity that can influence cravings and potentially lead to obesity, Jha explains. For instance, uridine has been shown to promote higher calorie intake.
If oral bacteria are demonstrated to influence obesity, Edwards suggests it could lead to innovative interventions, such as introducing beneficial oral microbes through gels, using prebiotics to foster specific bacterial growth, or employing targeted antimicrobials. “Behavioral strategies, like reducing sugar intake, can also significantly contribute to obesity prevention,” she adds.
Even if the oral microbiome acts as a consequence rather than a cause of obesity, its assessment can still provide valuable insights. Saliva tests can easily detect distinct microbial changes, which Jha believes could be useful for early obesity detection and prevention strategies.
How Microbial Activity in the Gut Affects Sleep Quality
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Research indicates that diet, particularly dietary fiber, may significantly influence sleep quality.
Prior studies have revealed associations between various sleep states and the gut microbiome. Notably, a lack of bacterial diversity suggests that improving dietary habits could enhance sleep quality. However, no study has yet identified specific microbial species consistently linked to sleep quality and the exact foods that support their growth.
A new systematic review by Wang Che from China’s Shandong First Medical University analyzes 53 observational studies comparing the gut microbiota of individuals with sleep disorders to those without, encompassing 7,497 individuals with sleep disorders and 9,165 without.
The researchers discovered that the overall bacterial species diversity, termed alpha diversity, was significantly lower in individuals suffering from sleep disorders. Those with insomnia, obstructive sleep apnea, or REM sleep behavior disorder showed a notable decrease in anti-inflammatory, butyrate-producing bacteria like Faecalibacterium, alongside an increase in pro-inflammatory bacteria such as Collinsella.
This underscores the importance of dietary fiber, as Faecalibacterium produces butyrate, which provides energy for colon cells, strengthens the intestinal barrier, and reduces inflammation, according to recent studies.
Researchers highlighted that microbial signatures could serve as criteria to differentiate clinical symptoms from other sleep-related issues, thus enabling targeted treatments.
According to Catherine Maki from the National Institutes of Health in Maryland, this study aligns with her group’s ongoing research, which has found a similar connection between sleep and butyrate production from Faecalibacterium.
“Collectively, these consistent findings highlight plausible microbiome metabolic pathways that link sleep and host physiology, warranting direct testing in future mechanistic and interventional studies,” Maki notes.
“This meta-analysis supports the correlation between Faecalibacterium and insomnia,” states Elizabeth Holzhausen from Michigan State University. “However, since these studies are observational, causality cannot be established.”
One hypothesis is that insomnia may negatively impact dietary fiber intake, leading to reduced levels of Faecalibacterium. Alternatively, reduced butyrate from Faecalibacterium could influence sleep quality, as suggested by research findings.
Controlled intervention studies are essential for confirming the causal relationship, Holzhausen emphasizes.
The findings further highlight the vital role of the gut microbiome in our sleep health and reveal potentially significant changes in gut microbial signaling pathways related to sleep-influencing processes such as hormone release, metabolism, and inflammation.
Maki suggests that while it’s too early to recommend increasing fiber intake to improve sleep, there is emerging evidence regarding dietary aspects that may influence sleep.
Some evidence suggests that certain foods, like tart cherry juice, can improve sleep quality. Improving overall dietary quality and increased fiber intake is linked to better sleep quality, though the specific dietary components influencing this relationship remain unclear.
Exploring Melaleuca Wetland Forests in New South Wales, Australia
Image Credit: Luke Jeffrey / Southern Cross University
The bark of a single tree can host trillions of bacteria, which may have a crucial yet underappreciated role in regulating greenhouse gases in our atmosphere.
Globally, the total surface area of tree bark is estimated to be around 143 million square kilometers, roughly equivalent to the Earth’s total land area. This extensive area represents a vast microbial environment known as the ashosphere, yet the microorganisms residing there have largely been overlooked by researchers. Learn more.
“It may seem obvious, but we’ve historically ignored tree bark,” states Bob Leung, a researcher from Monash University in Melbourne, Australia. “I had never considered that microbes existed in tree bark, but it makes perfect sense. Bacteria thrive everywhere, so it’s reasonable to expect them in the bark as well.”
Leung and his team initiated their research on a common wetland species known as paperbark (Melaleuca quinquenervia). Their findings revealed that over 6 trillion bacteria inhabit every square meter of tree bark, a density comparable to that found in soil.
Genetic testing of 114 bacterial species indicated that most belong to three primary bacterial families: Acidobacteriaceae, Mycobacteriaceae, and Acetobacteriaceae; intriguing as they remain entirely unclassified by science.
A fascinating characteristic of these microorganisms is their ability to metabolize hydrogen, carbon monoxide, and methane for energy. While hydrogen (H2) itself isn’t a greenhouse gas, it can enhance the warming effect of the atmosphere by reacting with other gases.
Researchers extended their study to include seven additional Australian tree species from diverse habitats, such as Casuarina, rubber trees, and banksias, and assessed their bark’s ability to absorb or emit greenhouse gases both in natural settings and laboratory experiments.
Under aerobic conditions, where oxygen is present, all bark types were found to consume hydrogen, carbon monoxide, and methane. However, when the trees were submerged in water—typical in wetland areas—the microbes adapted by producing these same gases.
Melaleuca quinquenervia trees in an Australian forest”
data-credit=”Luke Jeffrey / Southern Cross University”/>
The Canopy of Melaleuca quinquenervia
Image Credit: Luke Jeffrey / Southern Cross University
According to researchers, the collective amount of hydrogen absorbed by bark microorganisms worldwide is estimated to be between 600 million and 1.6 billion kilograms annually, which represents about 2% of the total hydrogen removed from the atmosphere.
This groundbreaking study marks the first effort to evaluate the role of tree bark in atmospheric hydrogen cycling, notes Luke Jeffrey at Southern Cross University in Lismore, Australia.
“Recognizing the hidden contributions of trees, beyond their role in carbon dioxide absorption, is crucial,” emphasizes Jeffrey. “Trees actively engage with other greenhouse gases, which is significant as H2 interacts with atmospheric methane and could help mitigate the increasing methane dilemma.”
However, the global landscape remains uncertain since the team evaluated only eight tree species from eastern Australia. “Significant research is needed across diverse forest types, tree varieties, microbial communities, and environmental conditions,” says Jeffrey.
Brett Somerelle of the Sydney Botanic Gardens asserts that this research underscores the gaps in our understanding of microbial diversity, composition, and functionality within tree bark ecosystems. “It will be fascinating to observe how these factors change across a broader spectrum of tree species, particularly in arid environments like savannahs and woodlands,” notes Summerell.
Understanding the relationships between fungi and bacteria in tree bark is equally critical, he adds.
The trillions of microorganisms that inhabit our intestines significantly impact our health.
Tom Leach/Science Photo Library
We frequently hear about the benefits of certain foods for your microbiome and overall health. However, the exact composition of a healthy gut microbiome has not been fully understood until now. A recent study involving over 34,000 individuals has advanced our knowledge of the microbial combinations that indicate low inflammation, robust immunity, and healthy cholesterol levels.
The gut microbiome influences various aspects of health, including the immune system, aging, and mental well-being. While many home testing kits claim to analyze gut composition, their effectiveness remains questionable, as defining a “healthy” microbial balance is complex.
Earlier efforts have mainly concentrated on species diversity, under the assumption that a greater variety of bacteria is beneficial. However, since microbiomes differ significantly between individuals, pinpointing specific microbial communities linked to particular health outcomes is challenging.
“The interplay between our diet, gut microbiome composition, and health is intricate. The only way to unravel these connections is through large sample sizes,” explains Nicola Segata from the University of Trento, Italy.
To develop a comprehensive understanding, Segata and his team analyzed data from over 34,500 participants in the PREDICT program, conducted in the UK and the US by the microbiome testing company Zoe, and cross-referenced the findings with data from 25 additional cohorts in Western nations.
Among the thousands of bacterial species in the human gut, researchers focused on 661 species present in over 20% of Zoe participants. They identified 50 bacteria closely linked to health markers, such as BMI and blood glucose levels, as well as 50 associated with poor health.
The 50 “good” bacterial species (22 of which are newly identified) seem to affect four key areas: inflammation and immune function, body fat distribution, and blood sugar regulation.
Healthy participants, with no known medical issues, carried approximately 3.6 more of these beneficial species than those with health conditions, while individuals at a healthy weight had about 5.2 more species compared to those who were obese.
Among the species analyzed, most bacteria classified as either “good” or “bad” belong to the genus Clostridium. Within this group, 40 species from the family Lachnospiraceae were highlighted; 13 showed positive impacts while 27 were linked to negative effects.
“This research identifies a subset of bacteria worth further exploring for their potential impacts on health conditions like high blood sugar and obesity,” states Ines Moura from the University of Leeds, UK.
The connection between these microorganisms and diet is analyzed through food questionnaires and data collected via the Zoe app, which suggests aiming for at least 30 different plant types each week and consuming three servings of fermented foods daily, promoting fiber intake and reducing ultra-processed food consumption.
The findings indicate that most microorganisms tend to enhance health with a balanced diet or exacerbate health issues with a poor diet. However, 65 of the 661 microorganisms exhibited an inconsistent relationship.
“These 65 bacteria highlight the complexity of our microbiome,” remarks Segata, who also consults for Zoe. “Their effects might depend on the presence of other microorganisms, specific bacterial strains, or particular dietary factors.”
This classification of “good” and “bad” bacteria enables researchers to assess an individual’s gut health on a scale from 0 to 1000, which is already being applied in Zoe’s gut health assessments.
“Think of a healthy gut microbiome as a network of chemical factories. We need a diverse range of species and a predominance of beneficial bacteria to generate health-promoting chemicals that benefit the entire body,” says Tim Spector, PhD from King’s College London and co-founder of Zoe.
Nonetheless, establishing a definitive model of a healthy gut microbiome is challenging. “Defining a healthy microbiome is not straightforward, as gut composition is impacted by diet and can shift due to environmental factors, age, and health conditions requiring long-term treatment,” adds Moura.
“We need to view our bodies and microbiomes as two intricate systems that combine to create an even more complex system,” says Segata. “A change in one element can subtly affect everything else. Understanding the causative relationships is often quite complicated.”
Segata advocates for larger studies to further clarify these links and represent a wider global population. However, once a health and microbiome baseline is set, he believes it should be feasible to recommend specific foods to optimize gut bacteria.
Fetch! Dogs can enhance our happiness in various ways
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Dogs have long been celebrated as beloved companions. However, recent studies suggest they may also improve our well-being by influencing our microbiomes. Experiments conducted on mice indicate that dog owners possess unique bacterial species that promote both empathic and social behaviors.
It’s evident that pets significantly enhance life satisfaction while also impacting our gut microbiome. Research highlights how this microbiome affects our mental health and plays a role in shaping our personalities. With dogs often topping the list of preferred pets, Takefumi Kikusui and his team from Azabu University in Japan sought to investigate whether pets influence our microbiomes and enhance our overall well-being.
To delve into this, researchers analyzed a survey where caregivers of 343 adolescents aged 12 to 14 in Tokyo reported on their social behaviors, including feelings of loneliness, tendencies toward aggression, and peer interactions. It was noted that approximately a third of these adolescents own pet dogs.
Findings revealed that, on average, dog owners perceived themselves as less socially withdrawn and exhibited less aggressive tendencies compared to their non-dog-owning peers. The research team also examined potential influencing factors such as gender and household income.
“Engaging frequently with your dog exposes you to their microorganisms (like licking),” explains Gerald Clarke from University College Cork, Dublin, Ireland. These bacteria can migrate to the gastrointestinal tract, potentially causing infections. They can also produce anti-inflammatory substances like short-chain fatty acids, which may improve mental health.
An essential part of the study involved transplanting oral microbes from dog owners and non-dog owners into germ-free mice. Fecal analysis showed that the introduced microorganisms successfully colonized the mice’s intestines.
In subsequent weeks, the researchers conducted various behavioral tests on the mice. In one test, a mouse was placed in a cage alongside another mouse trapped in a tube. Results indicated that mice transplanted with microbes from dog owners were significantly more inclined to interact with the tube than those who received microbes from non-dog owners.
This behavior suggests that the original mice displayed greater empathy and a willingness to help, Kikusui noted. Recent research has also revealed that mice can assist their pregnant partners in giving birth and even provide rudimentary first aid.
In another experiment, dog-owner transplants exhibited a tendency to sniff unknown mice in their cages more frequently than the other groups, indicating increased sociability, according to Clarke. “Such social behaviors can have implications across species, including humans,” he asserts. “Robust social networks are beneficial for mental health; having limited social exposure can be detrimental.”
Gaining further insights into these microbial shifts and developing probiotics that replicate these effects could potentially benefit individuals without dogs, Clarke suggests. However, studies in other regions with different microbial exposures are necessary.
Maintaining good oral hygiene may be especially important during pregnancy
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A popular saying suggests that “if you give birth to a child, your teeth will fall out.” While pregnancy is known to elevate the risk of dental issues, the underlying reasons remain somewhat unclear. Recent studies indicate that the oral microbiome alters during pregnancy, becoming less diverse and potentially more susceptible to inflammation.
Disruption of the oral microbiome, which comprises over 700 bacterial species, can lead to dental issues regardless of pregnancy status. However, Yoram Luzon and his team from Bar-Ilan University in Israel aimed to explore whether this typically stable ecosystem shifts during pregnancy. They collected saliva samples from 346 Israeli women across all three trimesters: 11-14 weeks, 24-28 weeks, and 32-38 weeks.
Their investigation revealed a decrease in species diversity in saliva samples starting from the transition between the first and second trimesters, continuing to decline throughout the pregnancy. A notable characteristic was the reduction in the number of species, with Akkermansia muciniphila, often hailed as a beneficial bacterium, declining alongside an increase in pro-inflammatory bacteria like Gammaproteobacteria and Synergystobacteria.
“While the oral microbiome is generally stable, we have noted a gradual decrease in its diversity over the years,” Louzoun observes. “Pregnancy accelerates this slow evolution, allowing changes that typically take years to manifest in just nine months.”
Despite being relatively minor overall, numerous factors may contribute to these changes. “Pregnancy involves a multitude of hormonal shifts and inflammation, leading to alterations in your microbiome,” explains Lindsay Edwards from King’s College London. “Dietary changes are frequent during pregnancy, and various factors such as nausea, medication cessation, and altered eating habits all play a role.”
The participants filled out questionnaires regarding their diets and health, allowing the researchers to identify similar yet distinct effects among different women. This included those who followed a gluten-free diet, took antibiotics, experienced stress, or were current or former smokers. “Many women quit smoking during pregnancy, but their prior smoking habits can impact their microbiome,” notes Dr. Luzon, emphasizing the potential long-term effects.
A parallel study found similar changes in the oral microbiomes of 154 pregnant women in Russia during their second and third trimesters.
Although pregnancy heightens the risk of dental complications, particularly in the early stages, Luzon does not definitively link oral microbiome changes to these issues. “We can’t conclude whether these microbiome alterations are beneficial or detrimental, but they are undoubtedly changing rapidly,” he states.
Conversely, Edwards suggests that shifts in microbial composition might be a contributing factor, highlighting that saliva tends to become more acidic during pregnancy, altering the types of bacteria present.
Valentina Biagioli and her colleagues from the University of Genoa in Italy assert that changes in the oral microbiome may correlate with variations in systemic hormone levels, as both systems potentially influence each other. “There exists a plausible biological link connecting the observed microbiome changes to prevalent dental issues during pregnancy, such as tooth loss,” she comments.
Disruption in the oral microbiome has been noted to relate to pregnancy complications. Consequently, establishing what constitutes an optimal microbiome during pregnancy could serve as a benchmark for monitoring pregnancy progression. “Once we establish the baseline oral microbiome of pregnancy, deviations can be detected,” Louzoun states.
Moreover, ongoing research aims to elucidate this microbiome’s role in the immune system, affecting both the health of the pregnant woman and her unborn child. “The microbiome is instrumental in shaping the immune system, fostering a reciprocal relationship,” Edwards explains.
In light of this, enhancing our understanding of how to sustain a healthy oral microbiome (e.g., via good dental hygiene and a balanced, nutritious diet) could yield significant benefits. “Microbiome changes may influence the inflammatory state of expectant parents and better prepare the child’s immune system, potentially affecting long-term health, allergies, infection susceptibility, and chronic inflammatory conditions,” cautions Edwards.
Fecal bacteria observed through an electron microscope
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Rats that received gut microbiomes from energetic human infants seem more inclined to explore their surroundings. This research suggests that the bacteria present in our guts during childhood may influence our personalities.
“This indicates that our microbes play an active role in emotional development, rather than merely being passive presence,” explains Harriet Scherekens from University College Cork, Ireland, who was not involved in the study.
Increasing research identifies a link between the microbial communities in our guts and various aspects of our well-being, emotions, and mood. For instance, individuals lacking certain gut bacteria types seem to face a higher risk of depression and anxiety.
While it remains uncertain whether bacteria are the cause of these emotional shifts or if the microbial communities alter in response to user actions, some evidence suggests that changes in the microbiome can influence an individual’s mood. For example, fecal transplants from depressed individuals to rats appear to induce depressive behavior. Conversely, depressed rodents receiving fecal transplants have shown improved symptoms upon preliminary examination.
To delve deeper into how the gut microbiome relates to temperament, Anna Artshinki and colleagues at the University of Turku in Finland conducted fecal transplants from infants into young rats.
Initially, the team evaluated the personalities of 27 toddlers aged 2.5 years using standard temperament assessments and an activity that encouraged play with bubble guns.
“Although we couldn’t study anxiety in 2-year-olds directly, we anticipated assessing behavioral differences, such as levels of inhibition versus sociability,” notes Artosinki.
From their evaluations, researchers classified 10 infants as energetic and 8 as inhibited and withdrawn. They then selected four energetic and four restrained infants (split evenly between genders) for fecal sample collection.
Fecal samples spiked with glycerol, alongside control samples, were transplanted into 53 22- or 23-day-old rats whose intestines had been pre-cleaned.
Artshinki’s team then subjected the rats to a variety of behavioral tests. They discovered that rats with microbiomes from energetic infants displayed a greater exploratory tendency compared to those receiving control implants or feces from inhibited infants.
To investigate how gut bacteria might influence the brain, the researchers also examined rat brain tissues for gene activity changes. This analysis indicated that rats receiving microbiomes from inhibited infants showed reduced activity in dopamine-producing neurons, a neurotransmitter linked to rewarding risk-taking behavior.
“This study effectively illustrates how the early childhood gut microbiome contributes to shaping behavioral tendencies,” Scherekens remarks. “By transferring microbiomes from children to rodents, researchers have created a valuable translation between microbes, human temperament, and brain function.”
This indicates a gut-brain pathway that impacts curiosity, reward, and motivation through the dopamine system, Scherekens adds.
Nonetheless, Artshinki cautions against overstating the implications. “Overall, adult temperament traits are strongly correlated with genetics, yet environmental factors—potentially including the microbiome—may play a role in certain behavioral distinctions.”
Artosinki emphasizes that whether microbes drive the differences in children’s behaviors remains an open question. It’s possible that children exhibiting more active traits interact with their environment and new foods in unique ways, thereby developing distinct microbiomes as a result.
Families that garden together have more diverse microbiomes
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New parents often juggle numerous worries like sleep schedules, breastfeeding, and even the color of their newborn’s poop, but the baby’s microbiome might not top their list of concerns. Experts suggest it shouldn’t be a priority just yet.
“The initial 1,000 days of life are vital for establishing the microbiome. Once established, altering it is quite challenging,” says Federica Amati from Imperial College School of Medicine. Early microbial colonization plays a significant role not just in physical health, but also in brain development, mental well-being in adolescence, and even in reducing the risk of dementia in later life.
During a meeting I attended, this point seemed crucial for new parents. Goodwood Health Summit held this month in Chichester, England. However, after speaking with nutritionists, microbiologists, and doctors, I became convinced that the importance of introducing microbes early in a child’s life is paramount. There are straightforward, cost-effective strategies to navigate your child’s microbiome in a beneficial direction.
Why early microbiome health is essential
We’re frequently reminded that the trillions of microorganisms comprising our microbiome influence our bodies in various ways, from safeguarding our gut lining to controlling inflammation. But they also impact the brain.
Microbial byproducts influence the formation and adjustment of brain connections during early childhood, a pivotal process for healthy brain growth. Bacteria also communicate with the brain through the vagus nerve, affecting mood and stress levels. Persistent inflammation due to an unbalanced gut microbiome may contribute to depression and neurodegenerative diseases.
Moreover, research has linked microbial imbalance to conditions such as Parkinson’s disease and autism. Early studies suggest that children with autism may present unique microbiome profiles, and fecal transplants from non-autistic donors may offer improvements in both gastrointestinal and behavioral issues.
Ways to nurture the ideal microbiome
Once a microbial ecosystem is set up, overhauling it can be quite difficult, making initial seeding vital. “It’s akin to changing an English garden into a rainforest,” comments Amati, who also serves as the head nutritionist for the Zoe health app.
So how can we foster the ideal growing environment? The gut microbiome begins to flourish even before birth. Bacteria and fungi present in the uterus are consumed by the fetus, and additional microorganisms are transferred during passage through the vaginal canal at birth.
Babies delivered by C-section generally have different gut bacteria, linked to a heightened risk of asthma and eczema, though these discrepancies typically diminish by 6 to 9 months of age.
The advantages of breastfeeding are even more pronounced, as breast milk contains sugars that promote the growth of beneficial bacteria like Bifidobacterium, which is absent in formula. If we liken the microbiome to a garden, these bacteria act as a protective barrier against harmful microbes.
Antibiotics can severely disrupt early microbiome seeding, eliminating both beneficial and harmful bacteria. While antibiotics are often essential, it is crucial for healthcare providers to prescribe them judiciously to safeguard the developing gut, states James Kinross, a colorectal surgeon at Imperial College London.
Post the first year, dietary choices have the most significant impact. Amati emphasizes that variety is crucial, stemming from whole foods rather than ultra-processed snacks commonly provided to young children.
As many parents are aware, young children are notoriously picky eaters. “Prenatal meals are simply a luxury,” explains pediatrician Nancy Bostock, who highlighted that young children don’t need extensive amounts of food. Persistence is key afterward; “Make 20 offers,” she advises. I implemented this approach and despite initial refusal, I continued to serve salmon every Monday for half a year, and my children now love it.
Introducing whole foods doesn’t have to break the bank either. “Canned lentils and frozen raspberries are excellent choices,” adds Amati.
The benefits of getting dirty
Is there a simple and overlooked way to enhance early microbial diversity? Embrace dirt! Research indicates that soil, plant, and human microbiomes are more interconnected than previously understood.
Kinross states that healthy, undisturbed soil is teeming with microorganisms that support the growth of nutrient-dense food for our microbiome. “Our health is inherently linked to the well-being of our soil. The soil microbiome shapes our food, which subsequently influences our health,” he notes.
Additionally, it appears that interacting with soil might directly introduce beneficial microorganisms into the gut, potentially enhancing immune function. Research on the Amish community, for instance, reveals that those who practice traditional farming methods exhibited stronger immune systems compared to Hutterite groups that utilize industrial agriculture. In animal studies, inhaling dust from Amish households (but not from Hutterite homes) showed protective effects against asthma through enhanced microbial immune signaling.
Families who garden together also show seasonal variations in intestinal soil bacteria, implying that microorganisms are introduced via home-grown produce or direct soil contact. Although the long-term influence on children’s microbiomes is still unclear, various studies indicate that families engaging in gardening tend to have greater microbial diversity and higher nutritional quality than those who do not.
You don’t even need a garden to reap these benefits. Spending time outdoors, tending to potted plants, and consuming home-grown produce are all advantageous for your microbiome, according to Amati.
It’s essential not to conflate getting dirty with the outdated “hygiene hypothesis,” which erroneously attributes inflammatory diseases to maintaining a clean home. What we truly require is exposure to beneficial microorganisms, rather than childhood illnesses that can be minimized by proper hygiene.
The old friend hypothesis suggests that humans evolved alongside beneficial microbes from soil, animals, and each other. Changes in our behavior have diminished contact with these beneficial organisms, potentially contributing to the rise of chronic diseases by reducing outdoor activity.
Promoting healthy dietary habits for your child’s mental well-being
Even after the crucial first 1,000 days, the microbiome remains malleable. That’s why fostering a passion for healthy foods in children is crucial, asserts Amati.
Bostock, who specializes in pediatric mental health including eating disorders, warns against limiting specific foods. “Repeatedly, I observe parents struggling to get their kids to eat certain things unless they consume this or that,” she notes. Emphasizing “good” versus “bad” foods can promote eating disorders and obesity, she asserts.
Instead, she advocates for continuous exposure to a range of foods, shared family meals, and celebrating the unique benefits of each food item (whether it be quick energy or bone-strengthening properties).
Lastly, Amati encourages educating children about their microbiome, stating, “Help them understand the role of these beneficial bugs. They find it fascinating and enjoy nourishing the good bacteria.”
Artificial sweeteners might support gut microbiome health
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Using low-calorie sweeteners instead of sugar may stimulate beneficial gut bacteria and aid in weight loss maintenance. This conclusion emerges from one of the longest studies on sweeteners, suggesting these alternatives might not be as detrimental as some previous reports indicate.
Several recent analyses have cast doubt on the health benefits of various low-calorie sweeteners. Although they are widely favored by those wishing to shed pounds, research indicates they may increase hunger, elevate blood sugar, and heighten the risk of heart-related illnesses. In 2023, the World Health Organization issued recommendations against using low-calorie sweeteners for weight management.
Nonetheless, there is a deficit of extensive research on sweeteners, particularly within the framework of a healthy diet. To investigate further, Ellen Black from Maastricht University in the Netherlands monitored their effects in individuals who substituted them for sugar. She and her team enlisted 341 overweight or obese adults in Europe and provided them with a low-calorie regimen for two months, resulting in an average weight loss of 10 kilograms.
Participants then adapted to a balanced diet with less than 10% of their caloric intake from sugar. During this weight maintenance phase, 171 participants were advised to completely forgo sweeteners, while the rest were motivated to swap sugary foods and beverages for lower-calorie sweetener options. Each participant had the option to use at least 16 different sweeteners, with no limit on their usage.
After 10 months, the group utilizing low-calorie sweeteners managed an average of 1.6 kilograms more weight loss compared to the sugar group. They also exhibited a higher presence of gut bacteria that produce short-chain fatty acids—beneficial compounds previously linked to blood sugar regulation, heart health support, and weight loss maintenance.
“This indicates that replacing sugar with non-caloric sweeteners in the diet may aid in weight maintenance,” says Braak. The outcomes of this study may vary from earlier research due to its extended duration and the examination of sweeteners alongside a healthy diet, she notes. Furthermore, prior studies often focused on just a few low-calorie sweeteners, many of which were not concurrently consumed.
Regarding the differences in gut bacteria, our grasp of the microbiome is still developing, according to Elan Elinav at the Weizmann Institute of Science in Israel. Thus, it remains challenging to decipher how the changes observed in the sweetener-consuming group will influence their health. He added that it is uncertain whether these transformations stemmed from weight loss, the intake of low-calorie sweeteners, or a combination of both.
The oral microbiome extracted from King Richard III, derived from analysis of his dental plaque, indicates he may have suffered from a condition that could lead to jaw deterioration.
In 2012, the skeletal remains of Richard III were found beneath a parking lot at the former Greyfriars Church in Leicester, England. Initially thought to be Richard III—who was killed in the Battle of Bosworth Field in 1485 and interred in Leicester—dental and skeletal evidence, including a head wound and spinal curvature, correlated with descriptions from his death. Subsequent genetic tests confirmed the identity of the remains.
Although Richard’s reign only lasted two years amid the Wars of the Roses, he significantly impacted English history, with allegations of plotting against his nephews while they were imprisoned in the Tower of London, alongside William Shakespeare’s portrayal of him as a malevolent figure in his famous play.
Nevertheless, details of Richard’s daily existence are scarce. To uncover more, Turi King and fellow researchers at the University of Bath, UK, collected samples of tartar—hardened dental plaque—from three of his well-preserved teeth.
Dental plaque is effectively a time capsule, retaining DNA from microorganisms and remnants of food. “The quantity of DNA obtained from Richard III’s tartar is among the highest recorded in archaeological contexts,” the researchers stated, noting the detection of over 400 million DNA sequences.
“No one has previously sequenced 400 million ancient DNA fragments; it’s an astonishing figure,” remarks Laura Weyrich from Pennsylvania State University. “This indicates that our capabilities with ancient DNA are likely more extensive than previously thought.”
Dr. King and his team identified almost 400 microbial species from the DNA, comparable in variety to samples from well-preserved dental tartar across Britain, Ireland, Germany, and the Netherlands over the last 7,000 years, spanning from the Neolithic to modern times. “It suggests that elite populations shared microbial strains akin to those of the broader populace, despite their affluent lifestyles and experiences,” Weyrich notes.
However, the research team could not collect adequate plant or animal DNA to determine Richard’s dietary habits. Nevertheless, previous studies on his bones from his last two years indicated he drank non-local wine and consumed large quantities of game, fish, and birds, including swans and herons.
Professor Weyrich indicated that results regarding the microbiome could vary if the team obtained samples from more than one tooth and compared them to similar teeth from groups in Germany or the Netherlands. She also mentioned that their limited sampling does not provide a comprehensive view of Richard’s oral microbiome, as distinct bacteria inhabit different areas of the mouth and different surfaces of the teeth.
The king’s well-preserved teeth may provide insights into his oral microbiome.
Carl Vivian/University of Leicester
One particularly prevalent bacterium identified is Tannerella forsythia, which is linked to periodontal disease, a serious gum infection that can lead to bone loss around the teeth. Given the poor oral hygiene of the 15th century, Richard had a cavity when he died at age 32, though this does not automatically indicate he had periodontal disease.
“Many individuals may harbor potentially harmful bacteria without becoming ill, while others could become infected,” explains Pierre Stollforth from the Leibniz Institute for Natural Products Research and Infection Biology in Germany. Weyrich adds that examining bone loss in the jaw could reveal if Richard suffered from periodontal disease.
“I’m particularly passionate about bridging social science, history, and genetics,” Stallforth states. “Having access to the dental tartar of historical figures is extraordinary as it enables us to gain deeper insights into their lives.”
Painted alongside scientist Manel Esterer, Maria Blagnas Morela contributed to research aimed at uncovering her secrets of longevity
Manel Esterler
From January 17, 2023, to August 19, 2024, Maria Blañas Morera from Spain was formally recognized as the oldest person in the world until her passing at the age of 117 years and 168 days. To investigate the secrets behind her remarkable longevity, a team of researchers explored her genetics, microbiome, and lifestyle.
When Morera was 116, the researchers gathered samples of her blood, saliva, and stool for genetic analysis. “Her genome was exceptional, enriched with variants known to extend lifespans in other species such as dogs, worms, and flies,” noted team member Manel Esterler at the Josep Carreras Leukemia Research Institute in Barcelona, Spain.
Showing no signs of dementia, Morera also possessed numerous genetic variants that helped maintain low blood lipid levels, protecting her heart and cognitive functions, according to Esteller. “Simultaneously, she lacked genetic mutations linked to conditions such as cancer, Alzheimer’s disease, or metabolic disorders.”
The researchers discovered that her lipid metabolism was one of the most efficient recorded. “Her lipid profile was remarkable, with very low cholesterol,” Esterer mentioned. “This efficiency was tied to her modest diet and genetic traits that enabled the rapid metabolism of damaged molecules.”
Esteller noted that Morela abstained from alcohol and smoking and adhered to a Mediterranean diet comprising vegetables, fruits, legumes, and olive oil, along with three servings of sugar-free yogurt daily.
Further assessments indicated that Morela maintained a robust immune system typically seen in younger individuals, alongside a gut microbiota characteristic of much younger people.
One of the most “astonishing” findings was a high concentration of Actinobacteriota bacteria in her gut, including well-known probiotics like Bifidobacteria. This abundance typically declines with age but tends to increase among centenarians and supercentenarians, offering various anti-aging benefits, such as reducing inflammation.
The researchers believe that her yogurt intake may have continually replenished her levels of Bifidobacteria. “This may suggest that dietary interventions can be linked to prolonged lifespan by influencing gut microbiota, along with preventing obesity and other health issues,” Esterer added.
Lastly, scientists examined whether there was a significant difference between Morela’s biological age and her chronological age by constructing an epigenetic clock based on her DNA methylation. This process involves adding or removing chemical tags that regulate gene expression. “Her biological age appeared 23 years younger than her actual age, contributing significantly to her longevity,” remarked Esterer.
Previous studies indicate that supercentenarians may carry genetic mutations associated with various medical conditions, such as Alzheimer’s disease and cardiovascular issues. Nevertheless, they somehow manage to overcome these obstacles and attain extraordinary lifespans. “There are limited studies on supercentenarians, and many only focus on one aspect, like microbiomes,” explained Esteller. “Our research demonstrates that overcoming such maladies is a blend of advantageous genetics and other elements, including beneficial gut microbiota, delayed biological aging indicated by a youthful epigenome, and lifestyle factors such as avoiding smoking, alcohol, and maintaining a low-fat diet.”
Richard Farragher from the University of Brighton in the UK acknowledged that the study highlights the plethora of assessments available to longevity researchers, cautioning that a case study of one individual could risk being perceived as a scientific “So-So Story.”
He explains that there are two key reasons behind the survival of extremely long-lived individuals: “First, there’s something extraordinary about them, perhaps genetically, and second, survival biases due to their fortunate circumstances,” said Farragher.
If luck plays a role, he asserts that to substantiate her longevity, Morela belonged to a family with a history of long lifespans that wasn’t documented in the study.
New research reveals a potential protective role for citrus fruits in preventing depression. Faecalibacterium prausnitzii, a type of bacteria found in the human intestine, and its metabolic activity, may influence the impact of citrus fruits and their flavonoids on mood.
Samuthpontorn et al. We report that citrus intake and its ingredients are positively associated with changes in abundance of 15 intestinal microbial species, including reduced risk of depression and enrichment Faecalibacterium prausnitzii. Image credit: Hans.
Depression is a widespread and debilitating condition that affects more than 280 million individuals around the world.
The exact cause of depression is unknown, and treatment is often ineffective.
70% of patients with depression are unable to respond to initial antidepressant treatment and experience unbearable side effects of the drug.
Diet may be a promising tool for preventing and managing depression.
Mediterranean diets are associated with a nearly 35% reduction in the risk of depression, and similar diets show a reduction in mood symptoms.
While the specific food groups underlying these findings remain unknown, recent studies have linked citrus fruits, such as oranges and grapefruits, with a reduced risk of depression.
However, the mechanisms explaining the relationship between diet and depression prevention remain unclear.
In a recent study, Dr. Raaj Mehta, a medical instructor at Harvard Medical School and a physician at Massachusetts General Hospital, along with colleagues, analyzed the interactions between citrus consumption, gut microbiome, and risk of depression in over 32,427 participants.
They prospectively examined the long-term effects of citrus intake on depression, the abundance of gut microbial species, and the potential metabolic pathways related to depression.
“I was collaborating with a talented postdoc named Chatpol Samuthpontorn. He came across a paper from 2016 suggesting that citrus fruits could reduce the risk of depression,” explained Dr. Mehta.
“This finding intrigued us, as we had access to extensive datasets that could help us investigate further.”
“One of these datasets was the Nurse Health Study II (NHS2), which began in 1989 to identify risk factors for major chronic diseases in women.”
“We found evidence in this dataset that nurses who consumed higher amounts of citrus fruits had a lower incidence of depression in the future.”
The authors found that consuming one medium orange per day could reduce the risk of developing depression by about 20%.
“When examining total fruit and vegetable consumption, or other individual fruits like apples and bananas, we did not observe a significant relationship with depression risk,” Dr. Mehta noted.
A unique aspect of this study was that a subset of NHS2 participants provided stool samples over a year for researchers to analyze.
“We used DNA sequencing results from these stool samples to identify links between citrus intake and specific bacterial species in the gut microbiota,” said Dr. Mehta.
“People who were not depressed had higher levels of this bacterium, and consuming more citrus was also linked to increased levels of Faecalibacterium prausnitzii.”
“This bacterium may play a key role in connecting citrus consumption with good mental health.”
“We also investigated similar studies involving men, as NHS2 only included women, and found an inverse correlation between Faecalibacterium prausnitzii and depression risk scores in this group,” Dr. Mehta added.
“This raises the question: Does Faecalibacterium prausnitzii contribute to positive mood?”
“One possible explanation is that these bacteria use metabolic pathways, such as the S-adenosyl-L-methionine cycle I pathway, to influence the production of neurotransmitters like serotonin and dopamine in the intestine,” Dr. Mehta explained.
“These neurotransmitters not only influence digestion but can also travel to the brain, where they affect mood.”
“We hope our findings encourage further research into the link between diet and mental health,” Dr. Mehta stated.
“People generally understand that food can impact mood, but researchers are just starting to unravel the specifics.”
A paper detailing these findings was published in the journal Microbiome.
____
C. Samuthpontorn et al. 2024. F. Prausnitzii Potentially modulates the association between citrus intake and depression. Microbiome 12, 237; doi:10.1186/s40168-024-01961-3
Recent studies have revealed the significant role of the gut microbiome, a vast community of microorganisms residing in the digestive tract, in influencing the body’s response to stress.
A new investigation published in Cell Metabolism proposes that gut microbes greatly impact the body’s circadian rhythm, particularly in managing stress levels throughout the day.
The research indicates that the activity and composition of gut microbes naturally vary, affecting the release of stress-regulating hormones like adrenaline and cortisol.
This breakthrough has sparked hopes among researchers of utilizing microbes as potential remedies for mental health conditions. According to Professor Paul Ross, Director of APC Microbiome Ireland, this study represents a significant advancement in comprehending the microbiome’s impact on mental well-being.
A disturbance in the microbiome balance can disrupt the body’s circadian rhythm, leading to sleep disturbances, immune system issues, and metabolic changes, affecting stress hormone release.
One particular microorganism, Lactobacillus, is believed to play a crucial role in regulating stress hormones.
The study’s lead author, Dr. Gabriel Tofani, emphasized the gut microbiota’s role in sustaining the body’s natural stress regulation processes.
To demonstrate the connection, researchers administered antibiotics to mice to reduce their microbiome, observing alterations in the release rhythm of the stress hormone corticosterone.
This research lays the groundwork for potential treatments targeting mental health conditions by understanding the intricate relationship between the gut and the brain and its impact on the body’s stress response.
Professor Ross highlighted the potential of microbiome-based interventions in enhancing mental health, noting that this study brings us closer to achieving that objective.
Read More:
About the Experts:
Dr. Gabriel Tofani: A researcher at Cork University in Ireland, focusing on circadian rhythms, stress, and gut microbiota.
Professor Paul Ross: Director of APC Microbiome Ireland, conducting research on the human microbiome, bacterial competition, physiology, and genetics.
Gut microbiota of racehorses may affect health and performance
Brian Lawless/PA/Alamy Stock Photo
Racehorses who have a more diverse gut microbiome as foals appear to perform better and have a lower risk of health complications.
The findings suggest that, as suspected in humans, there are critical periods in the horse’s gut microbiome for establishing a bacterial composition that may contribute to an individual’s long-term health and fitness.
Christopher Proudman Researchers from the University of Surrey in the UK analysed DNA sequences from fecal samples from 52 thoroughbred foals born at five stud farms in 2018.
The researchers took samples nine times over the first year of life: at 2, 8, 14 and 28 days of age, and at 2, 3, 6, 9 and 12 months of age. Once the animals were a year old, they were transferred to 29 racing training centres across the UK.
The researchers then measured the athletic performance of the two- and three-year-old horses during the races, and collected data on rankings and total prize money, as well as recording the horses’ respiratory systems, orthopedic health, and soft tissue health.
The team found that greater bacterial diversity at 28 days of age was associated with better performance in the race. The researchers also detected two bacterial families: Anaeroplasmataceae and Bacillaceae was associated with having a competitive advantage.
In contrast, low bacterial diversity at 1, 2 and 9 months of age was found to be associated with an increased risk of orthopedic and other problems, such as muscle strains and “hairline” fractures. The team also found that certain bacterial families, when abundant around the first week or two of life, were associated with an increased risk of respiratory and musculoskeletal diseases later in life.
Foals treated with antibiotics (which can affect gut microbiomes) during the first few weeks of life had significantly lower bacterial diversity than untreated foals at day 28, Proudman said. These animals subsequently produced fewer winnings and developed respiratory disease at 10 times the rate of untreated foals from age 6 months onwards.
The early health problems that prompted antibiotic treatment may have actually affected later performance and health. Simon Daniels Researchers from the Royal Agricultural University in Gloucestershire, UK, say it’s realistic to think that antibiotics themselves reduce bacterial diversity, leading to poorer health and performance.
“Although more evidence is needed before any firm conclusions can be drawn, it appears that how young horses are managed is particularly important for their later athletic performance,” Daniels says.
Rats in John Cryan's lab were withdrawn and anxious, behaving in ways that mirrored those who had been bullied at work and suspected they might encounter the bully again.
Believe it or not, the good news is that they fed some of these rodents a slurry of microbes extracted from their own feces. This may sound unpleasant, but it had a surprisingly positive effect on their behavior. “That was surprising,” says Cryan, a neurobiologist at University College Cork in Ireland. “We found that the behavioral changes that were induced by stress were normalized, and they started to behave like normal animals.”
Even more surprising, the mental changes weren't brought about by changes to gut bacteria, but by modifying another key aspect of the microbiome whose importance is only now being recognized: viruses.
After all, our bodies are full of these viruses – trillions of stowaways that do no harm to our health, but instead play a key role in nurturing a beneficial microbiome and making us healthier. Recent studies have found that the influence of this “virome” can be found throughout the body, from the blood to the brain. The hope is that tweaking it might lead to new ways of treating a variety of ailments, from inflammatory bowel disease and obesity to anxiety.
Microbiome Diversity
Over the past decade, there has been growing interest in the microbiome (all the tiny organisms that live on and in our bodies), but that interest has focused primarily on bacteria. Until recently, it was assumed that…
The rats in John Cryan's lab were withdrawn and anxious, behaving in ways that mirrored those who had been bullied at work and who feared they might encounter the bully again.
Believe it or not, the good news is that they fed some of these rodents a slurry of microbes extracted from their own feces. This may sound unpleasant, but it had a surprisingly positive effect on their behavior. “That was surprising,” says Cryan, a neurobiologist at University College Cork in Ireland. “We found that the behavioral changes that were induced by stress were normalized, and they started to behave like normal animals.”
Even more surprising, the mental changes weren't brought about by changes to gut bacteria, but by modifying another key aspect of the microbiome whose importance is only now being recognized: viruses.
After all, our bodies are full of these viruses – trillions of stowaways that do no harm to our health, but instead play a key role in nurturing a beneficial microbiome and making us healthier. Recent studies have found that the influence of this “virome” can be found throughout the body, from the blood to the brain. The hope is that tweaking it might lead to new ways of treating a variety of ailments, from inflammatory bowel disease and obesity to anxiety.
Microbiome Diversity
Over the past decade, there has been a surge in interest in the microbiome (all the tiny organisms that live on and in our bodies), but that interest has focused primarily on bacteria. Until recently, the assumptions were that…
Recent discoveries by scientists on the human gut microbiome, which consists of microorganisms like bacteria, archaea, fungi, and viruses residing in the gastrointestinal tract, may lead to new weight loss interventions in the future.
To be presented at the European Obesity Conference (ECO), researchers have identified specific microbial species that could either increase or decrease an individual’s risk of obesity.
Through a study involving 361 adult volunteers from Spain, scientists identified a total of six main species.
The lead researcher, Dr. Paula Aranaz, who obtained her PhD from the Nutrition Research Center of the University of Navarra, explained, “Our findings highlight the potential role of imbalances in various bacterial groups in the development and progression of obesity.”
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Participants were categorized based on their body mass index: 65 were of normal weight, 110 were overweight, and 186 were obese. Genetic microbiota profiling was conducted to analyze the type, composition, diversity, and abundance of bacteria present in their fecal samples.
The study found that individuals with higher body mass index had lower levels of Christensenella Minuta, a bacterium associated with weight loss in other studies.
<.p>Interestingly, there were gender-specific differences in the findings. For men, the species Parabacteroides hercogenes and Campylobacter canadensis were linked to higher BMI, fat mass, and waist size. On the other hand, for women, the species Prevotella copri, Prevotella brevis, and Prevotella saccharolytica predicted obesity risk.
According to Aranaz, “Fostering certain bacterial types in the gut microbiota, like Christensenella Minuta, may protect against obesity. Future interventions aimed at altering bacterial strains or bioactive molecules levels could create a microbiome resistant to obesity.”
While the study focused on a specific region of Spain, factors such as climate, geography, and diet could influence the results. These findings could lead to tailored nutritional strategies for weight loss that take into account gender differences.
About our expert:
Paula Aranaz is a researcher at the Nutrition Research Center of the University of Navarra in Spain, focusing on bioactive compounds to prevent and treat metabolic diseases. Her research has been published in journals like International Journal of Molecular Science, Nutrients, and European Journal of Nutrition.
Feces can reveal the bacteria in your intestines, but we don’t yet know which ones are best.
STEVE GSCHMEISSNER/Science Photo Library/Alamy
The science of our gut microbiome is often portrayed as one of medicine’s hottest new areas, but some argue that this research is overhyped. The latest aspect of this field to gain traction is test kits that allow you to send in a stool sample to find out if your gut bacteria are impacting your health.
Analysis found that these kits made claims that were not supported by evidence and that their testing procedures were not rigorous enough. So should companies even be allowed to sell them?
Research into the microbiome began about 20 years ago, with advances in DNA sequencing allowing scientists to learn more about our bodies and the bacteria that live within them.
Doctors have long known that some infectious diseases are caused by an overgrowth of harmful pathogens. The innovative idea is that more subtle microbiome disturbances can lead to conditions normally thought to have nothing to do with our gut, such as obesity, cancer and depression. did.
Despite the hype, this field has yet to change the world of medicine. Fecal transplants (transferring one person’s stool to another’s to increase beneficial bacteria) have so far been approved for only one rare medical condition. It is a severe form of diarrhea that usually affects hospitalized patients taking strong antibiotics. Additionally, probiotic products that purport to deliver “good bacteria” to the gut have generally not yet been shown to be effective in randomized trials, the gold standard of medical evidence.
But that hasn’t stopped some companies from selling microbiome-related products directly to the public. In response, the US National Institutes of Health launched an investigation into the increased use of fecal test kits by the general public.
Diane Hoffman Researchers from the University of Maryland identified 31 companies around the world that offer direct-to-consumer microbiome analysis kits. Based on the results of these analyses, users may be provided with a comprehensive report on their gut health, for example in the form of a numerical score, or told that their gut bacteria are associated with certain medical conditions. there is.
The big problem, Hoffman says, is that the science behind fecal DNA analysis is not yet advanced enough to draw reliable conclusions. Previous research has shown that Giving the same sample to different laboratories can give different results. This may be due to differences in how samples are processed or the reference databases companies use to determine someone’s microbiome.
Companies typically do not provide details about how they conduct their analysis, considering it commercially sensitive. “They don’t have to provide any information,” Hoffman said.
A further problem is that even if we could accurately quantify how much of each bacterial species is in someone’s feces, there is still no debate among doctors about which bacteria are associated with specific medical conditions or gut health. There’s a lack of consensus, Hoffman said. “They don’t have the data they need to determine whether someone’s gut microbiome is healthy or unhealthy.”
Some of the companies selling these tests have conflicts of interest. The research team found that nearly half of manufacturers sell supplements and probiotic products that claim to improve gut health and recommend them to consumers based on test results.
The findings are not surprising. leslie hoyles He is co-author of a review on the field at Nottingham Trent University in the UK. natural microbiology Last year, it concluded that the country was susceptible to “hype and misinformation.” When it comes to fecal testing, “it varies so much from person to person that it’s meaningless,” she says. “We don’t know what a healthy microbiome is.”
It might be tempting to think that if people want to waste money on fecal test kits, they should be allowed to do so. However, many other types of direct-to-consumer medical tests, such as pregnancy tests and COVID-19 tests, are regulated by government agencies and require sufficient supporting evidence. It’s time for microbiome testing to meet the same standards, Hoffman says.
No one is arguing that microbiome research should be abandoned. Although there is great promise in this field, it is clear that it is still in its early stages. So for now, it may be wise to just continue flushing your stool down the toilet.
It looked like a classic case of Alzheimer's disease. The man, in his 70s, had been experiencing severe cognitive decline for three years. Frequently forgetting the names of his family members, he was unable to drive or leave the house alone. Further deterioration seemed inevitable. But then his doctor tested him and found that his cerebrospinal fluid sample I noticed a fungus called Cryptococcus neoformans. They put him on antifungal medication and the results were amazing. Within two years he had his driver's license reinstated and returned to his job as a gardener.
Neuroscientists have long suspected that certain infections can increase the risk of dementia.For example, both Porphyromonas gingivalisthe bacteria behind periodontal disease, the herpes simplex virus that causes cold sores, It has been pointed out that there is a relationship with Alzheimer's disease.. However, cases of “reversible dementia” are emerging from the idea that our brains are teeming with microbes and that imbalances in this “brain microbiome” can make people more susceptible to neurodegenerative diseases. is beginning to arouse great interest.
Until recently, it was thought that the brain was free of microorganisms. This was especially due to the blood-brain barrier, a special membrane that protects pathogens and toxins in the blood from the brain. Therefore, the idea of a brain microbiome was controversial. But new research seems to confirm the case. Richard Leeds University of Edinburgh, UK and colleagues Analyzed data obtained from postmortem brains It is housed in four brain banks in the UK and US. They discovered a wide variety of microorganisms of different types.
A groundbreaking study proves that Alzheimer’s disease symptoms can be induced in healthy animals through gut microbiome transmission, highlighting the gut-brain connection and suggesting early treatment and treatment of Alzheimer’s disease. New avenues for personalized interventions have been opened.
Researchers have discovered a link between the gut microbiome and gut bacteria. Alzheimer’s disease disease.
For the first time, research has demonstrated that symptoms of Alzheimer’s disease can be transmitted to healthy young organisms through the gut microbiome, confirming its role in Alzheimer’s disease.
The research was led by Professor Yvonne Nolan from APC Microbiome Ireland, the world’s leading SFI-funded research center based at University College Cork (UCC), and Professor Yvonne Nolan from UCC’s Department of Anatomy and Neuroscience. Professor Sandrine Thure, King’s College London, and Dr. Annamaria Cattaneo, IRCCS Fatebenefratelli, Italy.
Scientists have discovered a link between Alzheimer’s disease and the gut microbiome. Pictured are Dr. Stephanie Grabracer and Professor Yvonne Nolan. Credit: UGC
This study confirms that the gut microbiome is emerging as an important research target for Alzheimer’s disease, given its sensitivity to lifestyle and environmental influences.
was announced on brainThis study shows that memory impairment in Alzheimer’s patients can be transferred to younger animals through gut microbiota transplantation.
Alzheimer’s disease, memory impairment, gut microbiome
Patients with Alzheimer’s disease had greater abundance of pro-inflammatory bacteria in their fecal samples, and these changes were directly correlated with the patients’ cognitive status.
Professor Yvonne Nolan said: “The memory test we investigated relies on the growth of new neurons in the hippocampal region of the brain. Animals with the gut bacteria of Alzheimer’s patients produced fewer new neurons and had impaired memory. I found out that it is true.”
“Alzheimer’s patients are typically diagnosed at or after the onset of cognitive symptoms, which may be too late, at least with current treatments. “Understanding the role of gut bacteria could pave the way for the development of new treatments and even personalized interventions,” Professor Nolan said.
Implications for treatment strategies and research collaborations
Alzheimer’s disease is the most common cause of dementia and is a general term for memory loss and other cognitive impairments severe enough to interfere with daily life. As the population ages, one in three people born today could develop Alzheimer’s disease. Funded by Science Foundation Ireland, scientists at UCC are leading the way in healthy brain aging by investigating how the gut microbiome responds to lifestyle influences such as diet and exercise. We are working to develop strategies to accelerate and advance the treatment of Alzheimer’s disease.
Professor Sandrine Thuret, Professor of Neuroscience at King’s College London and one of the study’s senior authors, said: ‘Alzheimer’s disease is an insidious disease and there is still no effective treatment. , represents an important advance in the understanding of this disease, confirming that the composition of our gut microbiota is causally linked to the development of the disease. This collaboration will help future research in this field. We hope that this will lead to potential advances in therapeutic interventions.”
Professor. John F. Cryan, vice president of research and innovation at UCC, who also worked on the study, said: He conducts research into related diseases such as Alzheimer’s disease, and with UCC he recognizes APC Microbiome Ireland as a leading institution in microbiome and brain health research. This research is consistent with our UCC Futures Framework and the University’s strategic plans in the areas of food, microbiome, health and, soon to be launched, Future Aging and Brain Sciences. “
Reference: “The microbiota of Alzheimer’s patients induces defects in cognition and hippocampal neurogenesis” Stephanie Grubrucker, Moira Marizzoni, Edina Silajzic, Nicola Lopizzo, Elisa Mombelli, Sarah Nicolas, Sebastian Dom-Hansen, Katia Scacellati, Davide Vito Moretti, Melissa Rosa, Carina Hoffman, John F. Cryan, Olivia F. O’Leary, Jane A. English, Aongus Lovell, Cora O’Neill, Sandrine. Ture, Annamaria Cattaneo, Yvonne M. Nolan, October 18, 2023; brain. DOI: 10.1093/brain/awad303
The research was carried out by Dr Stephanie Grubrucker, a postdoctoral researcher in collaboration with Professor Nolan, in collaboration with postdoctoral colleagues Dr Edina Siladzic from King’s College London and Dr Moira Marizzoni from IRCCS Fatebenefratelli in Italy. It was carried out. UCC collaborators were Professor Cora O’Neill, Dr Olivia O’Leary, Dr Sarah Nicholas, Dr Jane English, Mr Sebastian Dohm Hansen and Dr Aongus Lovell.
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