THE ARISING · Longevity & Healthspan
Urolithin A Supplement Failed to Improve Artery Function in Adults With Obesity
Four weeks of urolithin A, a supplement promoted for cellular health, did not significantly change how well arteries relax in middle-aged adults with obesity, according to a randomized clinical trial in JAMA Network Open.
The trial was double-blind and placebo-controlled. It enrolled 50 adults aged 40 to 64 with a body mass index of 30 or higher: 25 took 1000 mg of urolithin A and 25 took a placebo. The mean age was 50.7 years, mean BMI was 38.3, and 74% of participants were female. Follow-up averaged 28 days.
Urolithin A is a compound made by gut bacteria from polyphenols, plant chemicals found in some foods. The researchers describe it as an activator of mitophagy, the cell's process for clearing out damaged mitochondria, the structures that produce energy. Mitochondrial problems contribute to dysfunction of the endothelium, the lining of blood vessels, in obesity. That made the supplement a plausible candidate.
The main measure was brachial artery flow-mediated dilation, a standard test of how much an arm artery widens when blood flow increases. Mean flow-mediated dilation increased by 1.3 percentage points in the urolithin A group and 0.3 percentage points with placebo. The difference was not statistically significant. Other tests of blood vessel function, in the hand and fingertips, also showed no significant treatment effect.
The brain measures told a different story. During mental tasks, brain blood-flow responses were significantly greater after urolithin A than after placebo. The mean β coefficient, a measure of the size of the response, was 15.53 in the supplement group and −1.43 in the placebo group. Task performance, however, did not change.
The authors concluded that the supplement was well tolerated and feasible. They said its effect on task-evoked brain blood flow warrants further investigation. Seven participants, or 14%, were lost to follow-up.
The trial was registered at ClinicalTrials.gov as NCT05921266. What to watch next: whether longer studies of urolithin A, and trials focused on brain blood flow, can show if the brain signal translates into measurable benefits.