Composition of food supplements containing melatonin available in Portugal
DOI:
https://doi.org/10.1590/Keywords:
Melatonin, N-acetyl-5-methoxytryptamine, Dietary supplement, Medicine, IntoxicationAbstract
Melatonin straddles the boundary between food supplements and medicine. In Portugal, its classification is contingent upon a critical dosage threshold of 2 mg. This study aimed to detail the composition of melatonin-containing food supplements, available in Portugal based on their labels, and report the number of potential intoxications. Data was collected from 44 food supplements, and the difference in active ingredients was revealed towards the 16 approved medicines. Data on melatonin intoxication cases from 2018 to 2022 were obtained from the Portuguese Poisons Information Center (CIAV). Melatonin supplements, available in tablets, capsules, gummies, powders, or sprays, exhibited a recommended daily dose ranging from 1 to 1.95 mg. Only 20% contained melatonin alone, while the majority included plant extracts and vitamins. The absence of clinical studies supporting the efficacy of melatonin combined with plant extracts in these formulations raises concerns about their evidence-based effectiveness. Medicines contain 2 to 3 mg of melatonin per tablet, either immediate or modified release. Melatonin intoxication occurs mainly in children, with a higher prevalence between the first year of life and the age of four. Food supplements containing melatonin and plant extracts should be more carefully studied, including the potential adverse effects.
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