DIETARY melatonin, a hormone found naturally in many plant- and animal-based foods, may be linked to lower odds of obesity and depression, according to a large study of university graduates. Dietary melatonin is best known for its role in regulating sleep–wake cycles, but has also been associated with mood and metabolic health in experimental research.
How Dietary Melatonin Intake Was Measured
Researchers carried out a cross-sectional analysis using baseline data from an open cohort of 8,320 adult university graduates. Participants completed a validated 144-item food frequency questionnaire, which allowed the team to estimate dietary melatonin intake using published melatonin concentrations for each food. Melatonin content could be assigned to 82.6% of the food items, with levels ranging from 0–169.9 ng per gram. On average, participants consumed about 25,500 ng of melatonin per day.
Key Findings on Obesity and Depression
Most participants were women (67.7%), with a mean age of 36 years. When researchers compared people across quintiles of melatonin intake using adjusted statistical models, they found that obesity was less common in several intermediate intake groups. In the second, third, and fourth quintiles, the incidence rate ratios for obesity ranged from 0.72–0.81, indicating lower obesity risk compared with the lowest intake group.
Depression also showed an inverse association with dietary melatonin in the middle–higher intake range. In the third and fourth quintiles, the incidence rate ratio for depression was 0.79, suggesting that moderate to higher intake was linked to lower odds of depression. The pattern for depression was non-linear, implying that benefits may plateau or not simply increase with ever-higher intake.
No Clear Link with Other Chronic Diseases
Despite these signals for obesity and depression, the study did not find consistent associations between dietary melatonin and other chronic conditions, including hypertension, type 2 diabetes, metabolic syndrome, dyslipidaemia, obstructive sleep apnoea, or sleep duration. The authors emphasise that, because this was a cross-sectional analysis, it cannot prove cause and effect. They call for longitudinal and experimental studies to confirm whether increasing dietary melatonin genuinely reduces obesity and depression risk, and to uncover the biological mechanisms that might explain these associations.
Reference
Zanirate GA et al. The content of dietary melatonin in 119 food items and its relationship with chronic diseases: results of the CUME+ study. J Hum Nutr Diet. 2026;39(1):e70193.
