Dietary Melatonin Linked to Depression Risk: New Study

Key Summary

• Cross-sectional analysis of 8,320 Brazilian adults assessed links between dietary melatonin intake and chronic health outcomes.
• Higher melatonin intake from foods was associated with lower prevalence of obesity and depression, with the strongest effects at moderate intake levels.
• No significant associations were found with hypertension, metabolic syndrome, type 2 diabetes, obstructive sleep apnea, dyslipidemia, or sleep duration after adjustment.
• Coffee, rice, lentils, and beans were the main dietary sources of melatonin.
• Melatonin-rich diets reflected healthier nutritional patterns, including higher fiber intake and lower saturated fat.
• Causality cannot be inferred, underscoring the need for longitudinal studies.

Why Dietary Melatonin Matters in Obesity and Mental Health

Melatonin is widely recognized for regulating circadian rhythms, sleep, and mood. While supplements provide pharmacological doses, melatonin from food sources delivers physiological amounts that align more closely with endogenous secretion patterns.

In this context, researchers emphasize dietary melatonin as a nutritional marker, not a treatment. Experimental and observational studies have previously linked melatonin to anti-inflammatory, metabolic, and neuroprotective pathways. However, evidence examining habitual melatonin intake through diet and its relationship with chronic disease in adults has remained limited, prompting this investigation.

How was Dietary Melatonin Studied?

Published in the Journal of Human Nutrition and Dietetics, this cross-sectional analysis used baseline data from the CUME+ cohort, involving 8,320 Brazilian university graduates (mean age: 35.9 years).

Dietary intake was assessed using a validated food frequency questionnaire (FFQ). Melatonin concentrations were estimated for 119 food items using published databases and adjusted for total energy intake.

Primary health outcomes included:

• Obesity (BMI ≥30 kg/m²)
• Depression (self-reported diagnosis)
• Obstructive sleep apnea
• Hypertension
• Metabolic syndrome
• Type 2 diabetes
• Dyslipidemia
• Sleep duration

Regression models adjusted for sociodemographic, lifestyle, and clinical factors ensured robust statistical control.

Key Findings: Obesity and Depression Stand Out

The mean daily dietary melatonin intake was approximately 25,500 ng, with coffee, rice, lentils, and beans emerging as the main contributors.

After full adjustment:

• Higher dietary melatonin intake was inversely associated with obesity
• Moderate melatonin intake was linked to lower odds of depression
• No significant associations were observed with hypertension, metabolic syndrome, type 2 diabetes, sleep duration, or OSA
• Interestingly, the strongest protective associations appeared in intermediate intake ranges, suggesting a nonlinear relationship.

Clinical Implications and Research Outlook

For healthcare professionals, these findings reinforce the role of dietary patterns rich in plant-based staples and fiber in metabolic and mental health. 

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While causality cannot be established due to the cross-sectional design, the study supports further longitudinal and interventional research into dietary melatonin as a marker of healthier nutrition profiles.

Source:

Wiley Online Library