Recent studies reveal that vitamin C concentrations in the skin are closely linked to blood (plasma) levels, and can be enhanced by increasing fruit consumption. This research, involving 20 healthy individuals from New Zealand and Germany, demonstrated that eating two kiwifruits rich in vitamin C daily boosts plasma levels, elevates the vitamin content in the skin, enhances skin thickness (collagen production), and supports the regeneration of the skin’s outer layer.
Vitamin C (ascorbate) is found in all parts of the skin. Puller et al. conducted an extensive study to correlate plasma and skin ascorbic acid levels, emphasizing key skin compartments. Image credit: Pullar et al., doi: 10.1016/j.jid.2025.10.587.
“The strength of the link between skin thickness and vitamin C intake is striking,” remarked Professor Margriet Vissers from the University of Otago.
“We were taken aback by the significant correlation between plasma and skin vitamin C levels, which was notably stronger than that in other organs we examined.”
“For the first time, we have shown that circulating vitamin C penetrates all skin layers and correlates with enhanced skin function.”
“I’m incredibly proud of my team’s work and thrilled by the insights from our findings.”
The results imply that true beauty emanates from within, suggesting that vitamin C delivered through the bloodstream effectively supports skin function holistically.
“Vitamin C is essential for collagen synthesis.”
“This understanding has prompted the inclusion of vitamin C in numerous skincare formulations.”
“However, due to its high water solubility, vitamin C is not easily absorbed through the skin’s outer barrier.”
“Our findings indicate that the skin effectively absorbs vitamin C from blood circulation.”
“The uptake into the outer epidermal layers seems to be prioritized.”
The researchers utilized healthy skin samples from patients undergoing elective surgeries to establish the connection between plasma and skin vitamin C levels.
They carried out a pre- and post-dietary vitamin C intervention study involving 12 healthy participants in Christchurch, New Zealand, and Germany.
“Participants were instructed to consume two kiwifruits (equivalent to 250 micrograms of vitamin C) daily for eight weeks,” explained Professor Vissers.
“We collected skin samples before and after the dietary intervention, enabling us to analyze the basal skin layer in Christchurch and the integumentary skin layer alongside skin functionality tests in Germany.”
The researchers assessed skin sample regeneration, including skin thickness, elasticity, UV protection, and epidermal cell regeneration via ultrasound, to provide a comprehensive understanding of skin function.
“A significant finding was that participants’ skin thickness levels showed a notable increase, indicating enhanced collagen production and epidermal cell regeneration, essentially reflecting skin regeneration,” stated Professor Vissers.
Scientists propose that boosting dietary vitamin C intake can enrich all regions of your skin.
“It’s crucial to maintain optimal plasma levels, and we know that healthy individuals can easily reach these levels with approximately 250mg of vitamin C daily,” commented Professor Vissers.
“Nonetheless, vitamins are not stored by the body. Therefore, a healthy habit is to consume at least five servings of fruits and vegetables daily, including foods high in vitamin C.”
Refer to the study published on October 28, 2025, in the Journal of Research Dermatology.
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Juliet M. Puller et al. Dietary intake of kiwifruit, a high vitamin C food, improves vitamin C levels and skin function in human skin. Journal of Research Dermatology published online October 28, 2025. doi: 10.1016/j.jid.2025.10.587
The notion that reducing food intake could enhance longevity has existed for millennia. The ancient Greek physician Hippocrates famously stated, “If you overnourish the patient, you nourish the disease as well. Excess is contrary to nature.”
For decades, scientists have been investigating the validity of this advice.
The first major evidence emerged in the 1930s when American nutritionist Dr. Clive McKay discovered that rats on a restricted diet lived nearly twice as long as those with unrestricted access to food.
These rats did not suffer from constant hunger nor did they struggle for survival. On the contrary, they exhibited better health in old age, showcasing improved lung and kidney function, with no signs of cancer (until their food supply was increased post-experiment).
Since then, calorie reduction has been linked to increased lifespan and health across various life forms, including single-celled organisms, nematodes, flies, spiders, grasshoppers, guppies, trout, mice, hamsters, and dogs.
Why is this the case? The theory suggests that reduced food consumption activates a biological mechanism in your cells that encourages energy conservation.
When food is scarce, expending energy for activities like reproduction becomes counterproductive, especially in an environment lacking sufficient resources.
Thus, evolutionary biology suggests that animals in such circumstances should conserve energy, slowing their aging process until food availability improves, increasing their chances of remaining healthy enough to reproduce later.
Anti-aging effects of eating less
While there is ample evidence of caloric restriction in animals, obtaining reliable human data poses challenges.
Funding bodies, ethics committees, and participants are understandably hesitant to commit to long-term dietary interventions.
The most significant trial to date is the carrie trial (A Comprehensive Assessment of the Long-Term Effects of Reducing Energy Intake), where participants aimed to cut their intake by 25% over two years.
(Ultimately, the average reduction was only 12 percent, highlighting the difficulty of maintaining such a regimen, even with scientific support.)
Though two years is insufficient to conclusively determine longevity, participants did experience an average weight loss of 8 kg (17.6 lb), along with minor reductions in LDL cholesterol, blood pressure, blood sugar levels, and inflammatory markers.
Cutting back on protein
If you wish to apply this concept personally, an important question arises about what exactly should be reduced in your diet.
Recent studies indicate that a reduction in protein intake—the critical factor influencing our health—may be essential.
For example, one study by researchers at the University of Sydney found that mice on a low-protein diet lived approximately 30% longer than those on a protein-rich diet.
Specificity matters here. Since proteins are composed of 20 amino acids, reducing one or more of these could potentially extend lifespan.
Research indicates that lowering levels of “branched-chain” amino acids (BCAAs) might extend male mice lifespan by 30%. (The reasons behind the different effects in female mice remain unclear.)
In fact, reducing the specific amino acid isoleucine resulted in a 33% increase in male mice lifespan (compared to just 7% for female mice).
Ongoing research is investigating additional amino acids. For instance, methionine presents a delicate case.
Mice consuming a diet with 0.15% methionine lived 10% longer than those on a standard diet containing 0.4% of this amino acid.
Conversely, mice consuming 0.1% methionine often faced early death from rectal prolapse, prompting one to consider the risks involved.
Current research is shifting focus from merely restricting dietary components to optimizing them. However, with 20 amino acids, the permutations can be overwhelming.
Even experimenting with simple combinations of high and low doses of each amino acid could require over a million trials.
read more:
Genome-based amino acid diet
To tackle this complexity, scientists are examining our DNA, which directs protein synthesis. The building blocks of proteins are amino acids.
What if we provided living organisms with a diet that reflects the amino acid ratios found in their DNA?
Early research on fruit flies showed that those fed a diet aligned with their DNA ratios were larger, matured faster, laid more eggs, and had longer lifespans compared to those on standard diets.
A subsequent study involving mice found that when provided with the ideal dietary amino acid balance via their DNA, the mice demonstrated faster growth, increased muscle mass in males, and enhanced sperm production.
However, it’s yet to be determined if these mice will also enjoy prolonged lifespans.
Rapamycin (red) inhibits a protein known as mTOR (blue), which is linked to aging – Image credit: Science Photo Library
While the biological effects of reducing protein intake remain uncertain, scientists are making strides in understanding the underlying mechanisms. Similar to calorie restriction, this approach appears to significantly slow down the aging process.
A recent study published in May 2025 suggests that a low-protein diet may help in reducing DNA damage and mutations.
This doesn’t imply that proteins are directly mutagenic, but their influence on metabolism might lead to the production of “free radicals” that can harm DNA and cellular structures.
DNA mutations are known precursors to cancer and have long been associated with the aging process.
The exploration of how dietary adjustments can indirectly influence the rate of chemical “errors” in our DNA is a promising area for research.
Not everyone needs protein reduction
So, should you begin reducing your protein intake? While animal studies provide compelling evidence, human research yields more nuanced findings.
One 2014 study found that individuals consuming less protein tend to live longer than those with high protein intakes. A 50-year-old consuming under 45 g (1.6 oz) of protein daily may expect to live approximately four years longer than someone consuming 90 g (3.2 oz) daily.
Nonetheless, generalizing this advice proves challenging. In individuals over 65, the same study indicates the opposite effect. This might be due to age-related muscle loss, where protein consumption aids in weight gain.
Moreover, individuals consuming a higher proportion of plant-based protein did not face an increased mortality risk during midlife.
Hence some contend that risks may stem more from excessive red and processed meat intake than protein consumption itself.
Another factor could be that plant proteins are generally lower in certain amino acids, like methionine, meaning high vegetable consumers might naturally have a lower methionine intake.
Sadly, no comprehensive human studies have been conducted to deliberately restrict specific amino acids.
However, it would be intriguing to research this approach in humans, not through protein powders but via dietary combinations that adhere to our genetic requirements and can be easily integrated into daily nutrition.
Such findings may help mitigate the downsides associated with strict diets. Reducing food variety often leads to reported feelings of hunger, chills, decreased libido, irritability, and slower recovery from injuries.
As an old saying in longevity science goes, while dietary restrictions might not extend your life, they can certainly make your life feel longer.
Medication alternatives to protein restriction
Perhaps the answer lies not in our kitchens but in pharmaceuticals. A drug called rapamycin, for example, activates cellular recycling pathways that mimic those triggered during dietary restriction, leading to lifespans increased by up to 60% in mice.
Diabetes medications that lower blood sugar are another avenue to induce caloric reduction and extend mouse lifespans.
Moreover, GLP-1 agonists such as semaglutide (Ozempic) have showcased the potential to alleviate various conditions by directly curbing appetite.
Could these or other medications help us maintain health without adhering strictly to lengthy dietary regimens?
As a person interested in a long, healthy life, but wishing to avoid being a hungry centenarian, I eagerly anticipate the initiation of clinical trials.
An illustration depicting the drug rapamycin (red) inhibiting the protein complex MTORC1, influencing cell functionality
Science Photo Library/Getty Images
The drug rapamycin shows effects on life extension that are nearly comparable to calorie restriction, based on the largest study exploring the lifespan of various vertebrate species.
Researchers are probing if lifestyle changes like diet and exercise can enhance longevity while mitigating aging-related health issues. For instance, calorie restriction, when balanced with nutritional needs, has demonstrated extensions of lifespan in non-human animals of up to 40%.
“In our field, we have long recognized that calorie restriction often yields positive results,” says Matt Kaeberlein, who was not involved in the recent research from Washington University in Seattle.
Another area of interest lies with potential anti-aging medications, such as rapamycin, initially developed as an immunosuppressant. The combination of rapamycin with the cancer treatment trametinib has shown a 30% increase in mouse lifespan earlier this year.
Currently, Zahida Sultanova from the University of East Anglia, along with her collaborators, is reviewing data from 167 studies on lifespan interventions across eight vertebrate species, such as fish, mice, rats, and rhesus monkeys, though not in humans.
The findings indicated that dietary restrictions, regardless of whether they primarily involve calorie reduction or intermittent fasting, extend the lifespan of all eight species, regardless of sex. Rapamycin appears to produce effects similar to these. They also examined the type 2 diabetes medication metformin, which has been suggested as a potential longevity stimulant, but found no benefits regarding lifespan.
Kaeberlein also warns against using medication or limiting calories solely to combat aging, as this could be linked to physical debilitation and mental health issues. “We must better understand the ratio of risks to rewards in humans before making such decisions,” he states. “Rapamycin might be beneficial for certain individuals, and ongoing research aims to clarify who those individuals are.”
Other medications similar to rapamycin, termed Rapalogs, might offer even more promising options with fewer adverse effects for lifespan extension, claims Sultanova.
Kaeberlein adds that while these results align with existing literature, “the effect sizes observed in shorter lifespans typically surpass those in longer ones, so caution is warranted when comparing across species.”
Measuring the Amount of Breast Milk in Breastfeeding
Lebedinskaia Natalia/Getty Images
Parents may soon be able to monitor how much breast milk their baby consumes through devices that provide real-time notifications to their smartphones.
“The anxiety surrounding breastfeeding often stems from the uncertainty about how much milk a baby is receiving,” explains Daniel Robinson from Northwestern University, Illinois. “This can heighten stress for nursing mothers, parents, and healthcare professionals.” Insufficient nutrition can lead to slower weight gain in infants and, in severe cases, dehydration.
Clinicians typically evaluate breastfeeding effectiveness by comparing weights before and after feeds and monitoring diaper changes. However, these methods are somewhat cumbersome and imprecise, according to Robinson.
To create a more precise measurement system, he and his team engineered a device featuring four electrodes, each 4 cm wide, that attach to the breast away from the nipple. Two electrodes transmit a very low electrical current across the breast, while the other pair receives it.
This device relays recordings to a smartphone app, leveraging the weaker electrical signals produced as milk is released, enabling real-time calculations of milk volume, Robinson shares.
Researchers tested this system with breastfeeding mothers who expressed milk into a bottle for approximately 15 minutes. The device’s average milk collection was within 2 ml of the actual amount, as each participant expressed about 50 ml.
This innovation could allow parents to monitor their baby’s nutrition more effectively, potentially leading to timely adjustments such as supplementing with formula under medical guidance, Robinson notes.
The device consists of sticky electrodes that adhere to the breast
Northwestern University
In another trial, a woman used the device while nursing, and the app reported that her baby consumed 24 ml of milk. This closely matched the 20 ml estimation derived from traditional weight measurements taken before and after feeding, Robinson notes.
“A prevalent reason many mothers discontinue breastfeeding is the belief that their milk supply is inadequate, making this technology crucial for determining its accuracy,” states Mary Fewtrell from University College London.
However, to ensure the credibility of this device, further research is necessary to understand any potential impacts on milk production, long-term side effects, and whether parents find it desirable, observes Amy Brown from Swansea University, UK.
Excessive dietary sodium increases blood pressure, while a high potassium diet has the opposite effect. The underlying mechanism is alleviated by sex and includes multiple organs and tissues. How do high potassium-induced alternatives in renal function differ between men and women with lower blood pressure? To answer these questions, a duo of researchers at the University of Waterloo conducted computer simulations to simulate the homeostasis of whole body fluids and electrolytes, simulating the effects of sodium and potassium intake on blood pressure.
Melissa Stadt & Anita Layton suggests that increasing the ratio of dietary potassium to sodium intake may be more effective in lowering blood pressure than simply reducing sodium intake. Image credit: Melissa Stadt & Anita Layton, doi: 10.1152/ajprenal.00222.2024.
Hypertension affects more than 30% of adults around the world. It is the main cause of coronary heart disease and stroke, and can lead to other distress such as chronic kidney disease, heart failure, irregular heartbeat, and dementia.
“We usually recommend eating less salt when we have high blood pressure,” said Professor Anita Leighton, author of the study.
“Our research suggests that adding potassium-rich foods to a diet such as bananas and broccoli can have a greater impact on blood pressure than cutting off sodium.”
Potassium and sodium are both electrolytes, which help the body send electrical signals to contract muscles, affect the amount of water in the body, and perform other essential functions.
“Early humans ate a lot of fruits and vegetables. As a result, our body’s regulatory system may have evolved to work best on a high potassium, low sodium diet.”
“Today, Western diets tend to be much higher in sodium and lower in potassium.”
“It may explain why hypertension is seen primarily in industrialized societies, not isolated societies.”
Previous studies found that increased potassium intake helps control blood pressure, but researchers have developed a mathematical model that successfully identifies how potassium-sodium ratios affect the body.
The model also identifies how sex differences affect the relationship between potassium and blood pressure.
Scientists have found that men develop hypertension more easily than premenopausal women, but men are more likely to respond positively to an increased potassium-to-sodium ratio.
“Mathematical models like those used in this study allow these types of experiments to identify how different factors affect the body quickly, cheaply, and ethically,” they said.
Team’s paper Released in March 2025 American Journal of Physiology-Renal Physiology.
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Melissa Statt and Anita T. Leighton. Regulation of blood pressure by dietary potassium and sodium: Gender differences and modeling analysis. American Journal of Physiology-Renal PhysiologyPublished online on March 3, 2025. doi: 10.1152/ajprenal.00222.2024
In a study led by Sapienza University in Rome, caffeine intake was positively correlated with the proportion of circulating endothelial progenitor cells in lupus patients.
Orefice others. studied the role of caffeine intake on endothelial function in lupus patients by evaluating the effects of caffeine intake on circulating endothelial progenitor cells. Image credit: Sci.News.
Vascular disease, damage to blood vessels, and the resulting heart attacks and strokes are among the leading causes of death in the general population.
These risks are even higher in patients with inflammatory rheumatic diseases such as lupus and rheumatoid arthritis.
This is due both to the disease itself and to some of its treatments, especially cortisone derivatives.
Until now, doctors’ recommendations for reducing these vascular risks have primarily been about avoiding risk factors.
This includes traditional recommendations such as smoking cessation, reducing cholesterol, and managing high blood pressure, as well as stopping inflammation and reducing the dose of cortisone medications.
But researchers at Rome’s Sapienza University think that doing something that’s actually fun may help patients improve their vascular health.
Research suggests that the caffeine found in coffee, tea, and cocoa helps regenerate the lining of blood vessels and actively supports endothelial progenitor cells, a group of cells involved in blood vessel growth.
Diets rich in vitamin D (found in fatty fish and eggs) and vitamin A (found in many fruits), polyunsaturated fatty acids and low in sodium appear to play a role in reducing inflammatory burden well known.
“We were also wondering about caffeine,” said Dr. Fulvia Ceccarelli and colleagues.
“In addition to its well-known stimulant effects on the body, caffeine also exerts anti-inflammatory effects because it binds to receptors expressed on the surface of immune cells.”
“The effects of caffeine intake on cardiovascular health have been widely investigated, but results are contradictory.”
The study authors surveyed 31 lupus patients without traditional cardiovascular risk factors using a 7-day dietary questionnaire.
After a week, the researchers drew blood from patent patients to measure blood vessel health.
They found that patients who consumed caffeine had better blood vessel health, as measured through the endothelial cells that form the critical lining of blood vessels.
“This study is an attempt to provide patients with information about the possible role of diet in controlling the disease,” said Dr. Ceccarelli.
“The results will need to be confirmed through longitudinal studies aimed at assessing the actual impact of coffee consumption on the course of the disease.”
Research indicates that a lack of dietary fiber may result in accelerated brain aging, potentially contributing to the prevalence of Alzheimer’s disease and dementia. Expert nutritionists, such as Dr. Emily Leeming and Nutritional Psychologist Kimberly Wilson, presented this theory at the Cheltenham Science Festival.
In fact, dementia, a condition characterized by memory loss, is described as a model of accelerated brain aging by Wilson. This highlights the importance of dietary fiber for brain health and overall well-being.
Most adults in the UK are not consuming enough fiber, falling short of the recommended intake of 30g per day for optimal health. This deficiency poses a risk factor for various health conditions, including cognitive decline and neurodegenerative diseases.
According to Leeming and Wilson, consuming fiber-rich foods is essential for brain protection. Fiber is metabolized by gut bacteria, producing short-chain fatty acids that play a crucial role in maintaining the integrity of the blood-brain barrier. These fatty acids help prevent the passage of harmful substances into the brain.
If you are not getting enough fiber in your diet, Leeming suggests incorporating fiber-rich foods like rye bread, beans, nuts, and vegetables. Additionally, consuming dark chocolate and root vegetables with the skin on can help boost your fiber intake.
By increasing fiber consumption, individuals can support their gut health, manage blood sugar levels, and reduce the risk of chronic diseases. Leeming and Wilson emphasize the importance of fiber for overall health and well-being.
Our experts, Kimberly Wilson and Dr. Emily Leeming, have extensive experience in nutrition and psychology, respectively. Wilson is a licensed psychologist and author, while Leeming is a Registered Dietitian and Research Fellow with a focus on the gut microbiome.
It is already known that excessive salt intake increases blood pressure.
Toufik Ahmed/iStockphoto/Getty Images
Researchers have found that people with the skin condition have higher levels of sodium in their urine, suggesting that excessive salt intake may be linked to eczema.
To see if salt plays a role, Katrina Abuaballah Researchers at the University of California, San Francisco (UCSF) looked at urine sample data from more than 215,800 adults who took part in the UK Biobank study, more than 10,800 of whom had eczema.
The researchers used each participant's urine sample to estimate urinary sodium excretion over a 24-hour period. About 90% of dietary sodium is excreted in the urine.This waste product therefore provides a relatively reliable way of measuring a person's salt intake.
Overall, study participants were estimated to have excreted an average of 3.01 grams of sodium in their urine over a 24-hour period. Typically around 2.5 grams per dayThis is the equivalent of 6 grams of salt, or 1 teaspoon.
The researchers found that for every gram of sodium excreted, participants were 11 percent more likely to be diagnosed with eczema, and their risk of ever developing eczema at any one time increased by 16 percent.
The team acknowledges that a single urine sample may not accurately reflect an individual's typical salt intake, but in another part of the study, the researchers looked at the daily diet of a different group of more than 13,000 U.S. adults and found further correlations between high salt intake and eczema.
In previous studies, Sodium activates immune system cells“The immune system responds to allergens and irritants in a way that triggers several inflammatory pathways,” Abuaballah said. People with eczema have an overactive immune response to allergens and irritants, which causes skin inflammation and subsequent symptoms.
Although the study suggests a link between high urinary sodium levels and eczema, team members say more research is needed to prove that the former causes the latter. Brenda Chanalso at UCSF.
“It's too early to say whether lowering sodium in the diet can reduce the severity or risk of developing eczema,” he said. Karsten Flor At King's College London.
Abuaballah said her team will soon begin enrolling participants for a National Institutes of Health-funded study that will look at the relationship between dietary sodium, sodium levels on the skin, and eczema severity.
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