As temperatures in Australia drop, ‘golden milk’, a blend of warm milk, turmeric, spices, and honey, is gaining popularity on social media. This comforting beverage not only tastes great but also boasts medicinal properties, primarily due to curcumin—the yellow pigment in turmeric. Curcumin is touted for its anti-inflammatory properties, which may aid in fighting diseases such as cancer, arthritis, allergies, Alzheimer’s, and menopause. But is the evidence behind these claims robust?

Turmeric has a storied history in South Asian cooking and medicine spanning thousands of years, but it has recently emerged as a “superfood” in Western cultures. This shift can be attributed to extensive research conducted by Bharat Agarwal, a former biochemist at the University of Texas MD Anderson Cancer Center. Since the early 2000s, Agarwal and his team have published over 100 studies demonstrating that curcumin reduces inflammation and promotes cell death across nearly all types of cancer.This research has fueled the surge in popularity of turmeric lattes and curcumin supplements, prompting further investigations. To date, U.S. health agencies have allocated approximately $275 million to curcumin research since 1990, especially in light of Agarwal’s contributions.

The notion that a colorful, flavorful spice rooted in Ayurvedic traditions could transform modern medicine is captivating. However, questions regarding the integrity of Agarwal’s findings have emerged. In 2012, the U.S. Department of Health and Human Services’ Office of Research Integrity informed MD Anderson of allegations regarding potential research misconduct. At least 65 of Agarwal’s papers have faced scrutiny, although this does not confirm any fraudulent activity. Following an internal investigation, Agarwal left the cancer center, and 30 of his studies have since been retracted or denied publication due to concerns over data reliability. Despite this, Agarwal has authored many articles still frequently cited in the literature. New Scientist was unable to obtain a comment from him.

It is quite remarkable that curcumin has attracted such a volume of research. However, an examination of its chemical properties suggests it may not serve as an effective drug. During my PhD focused on cancer drug development, a lab colleague found curcumin challenging to work with due to its low solubility and instability. A 2017 review published in the Medicinal Chemistry Journal, led by Kathryn Nelson from the University of Minnesota, concluded that “curcumin is an unstable, reactive, and non-bioavailable compound, thereby having very limited therapeutic potential.”

Curcumin’s poor solubility in water limits its absorption into the bloodstream after consumption, often leading to most of it remaining in the intestines and being excreted. In a recent Dutch study, curcumin was hardly detectable in participants’ blood. This finding applied even to those taking higher doses of “fortified” supplements designed to enhance absorption with black pepper and piperine. The blood concentration levels recorded were over 100 times lower than those needed to exhibit activity against cancer cells in laboratory settings.

This ineffectiveness may explain why curcumin has fallen short in demonstrating notable results in clinical trials for conditions like cancer, arthritis, and more. According to Nelson and her research team, curcumin is “like a missile that keeps detonating on the launch pad, never reaching its target.”

Too Many Claims

Additionally, there are growing concerns regarding the safety of turmeric and curcumin supplements. While turmeric is safe when consumed in culinary quantities, concentrated curcumin supplements pose risks. Since curcumin constitutes only about 5% of turmeric’s dry weight, concentrated versions can cause liver complications in susceptible individuals. According to the U.S. National Institute of Diabetes and Digestive and Kidney Diseases, “Turmeric is the most common cause of herb-related liver damage,” particularly due to highly bioavailable curcumin formulations.

Symptoms of liver damage include jaundice, dark urine, and gastrointestinal discomfort. Although these issues often resolve after discontinuing the supplement, some cases have resulted in liver failure and fatalities.

Contamination is another risk associated with turmeric products. In the U.S., various brands of powdered turmeric spice were recalled between 2011 and 2016 due to lead chromate contamination, which was added to enhance color intensity. Certain children consuming these tainted products exhibited dangerously elevated lead levels in their blood. Additionally, turmeric supplements in Norway and Sweden were linked to hepatic damage, with some containing a painkiller, Nimesulide.

While I hope the turmeric in my kitchen is safe, brewing “golden milk” soothes my spirit. I plan to make it a winter staple, knowing that its true magic lies in its unique flavor rather than miraculous health benefits. Agarwal and his colleagues once noted in a paper published in The Journal of the American Society of Pharmaceutical Scientists that curcumin’s effectiveness may seem “too good to be true.” Indeed, they were right.