Efeito da melatonina exógena sobre o padrão alimentar de trabalhadoras noturnas com excesso de peso

Abstract

Background: Melatonin is a pineal hormone that plays an important role as an endogenous synchronizer of circadian rhythms and energy metabolism. As this circadian component has been closely related to eating behavior, an important question would be whether melatonin supplementation could influence food intake. However, this topic has not been addressed by literature yet, especially in individuals with overweight, chronic circadian misalignment, and frequent nutritional problems, such as shift workers. Aims: 1) To synthetize the results from clinical and preclinical studies on the effects of exogenous melatonin on food intake and appetite-regulating hormones; 2) To determine the interval between the last meal and bedtime and its relationship with diurnal and nocturnal sleep parameters, as well as the adequacy of this meal; and 3) To evaluate the effects of melatonin supplementation on the quality-quantitative aspects and temporal distribution of food intake in female overweight night workers, according to circadian misalignment and chronotype. Methods: To address the first aim, a systematic review of intervention studies was carried out. To address aims 2 and 3, a randomized, double-blind, placebo-controlled, cross-over clinical trial was conducted with 27 female overweight nursing professionals who worked permanent night shifts (age= 37.1 (SE ±0.6) years, BMI= 29.8 (SE ±0.4) kg/m², lifetime exposure to night work= 9.1 (SE ±0.7) years). Protocol was implemented under real-life conditions for 24 weeks, in two randomly allocated conditions (12 weeks of melatonin supplementation and 12 weeks of placebo). The quantitative aspects of food intake (total energy intake (TEI) and the proportion of calories from macronutrients) and meal timing were assessed by food diaries. Results: Findings on the influence of exogenous melatonin on food intake are heterogeneous and clinical trials are limited. In our trial, no significant modifications in total energy intake, macronutrient distribution, types of foods consumed and meal timing were observed after melatonin or placebo supplementation. Different patterns of circadian misalignment and chronotype did not interfere with these results. Final considerations: The quality-quantitative aspects of the diet of female overweight night workers remained unchanged after melatonin supplementation. Circadian misalignment and chronotype did not interfere in these results. In parallel with previous studies on the topic, these results suggest that the metabolic effects of melatonin may occur independently of food intake.