Contrary to the popular belief that eating carbohydrates in the evening is bad for you, scientists specialising in the study of biological rhythms have shown that this is exactly when this type of nutrient should be consumed in order to enhance its metabolism. The importance of gaining an understanding of biological rhythms and the hormone that regulates them, known as melatonin, and applying this knowledge therapeutically has gained in significance in the field of biomedicine as a result of evidence of its effects on the cardiovascular, nervous and digestive systems and even in cancerous processes.
Researchers from the Universities of Göttingen (Germany), Geveva (Switzerland), Leuven (Belgium), Ferrara (Italy), Barcelona, León and Vigo met today on the Vigo Campus at a new BIOCAPS scientific seminar to share their latest findings in this field, especially as regards the role of melatonin and biological rhythms in ageing, neurodegenerative and cardiovascular diseases, obesity and diabetes, with the Galician biomedical community..
During this scientific meeting organised by the Biomedical Research Institute (IBI), Professor Inge Depoortere, from the University of Leuven explained that workers who work different shifts and people who suffer from jet lag are more likely to develop metabolic disorders such as obesity, type 2 diabetes and gastrointestinal disorders. “These disorders arise due to the fact that people eat their main meals at night rather than ingesting more calories or less healthy foods. Our findings indicate that when we eat as well as what we eat determines our predisposition to suffering gastrointestinal inflammation or obesity", she explained.
Professor Depoortere also pointed out that the proverb “breakfast like a king, lunch like a prince and dine like a pauper” has a ring of truth to it provided we also take into account what we eat and when. “Missing breakfast is clearly a mistake, although it should also be rich in proteins as it has been shown that this is associated with a reduced appetite and lower calorie consumption during the rest of the day”, she noted. Lunch should be eaten early as it has been demonstrated that overweight people who eat later lose less weight. Finally, the evening meal should be eaten three hours before going to bed and should be rich in carbohydrates as this “enhances the feeling of fullness during the day”.
Melatonin is responsible for provoking sleep and appetite, stimulating growth and activating reproductive function. In addition, it has recently been demonstrated to act as a powerful antioxidant that neutralises free radicals, thus making it a powerful cancer inhibitor, amongst other functions. This was explained in greater detail by Javier González-Gallego, Head of the Institute of Biomedicine at the University of León, who has found a dual role for this hormone in cell death in the liver.
“Melatonin stimulates tumour cell death but inhibits cell death in healthy liver cells or in those affected with a non-tumoural disease, in other words it exerts a protective effect”, he explained, adding that other protective effects of melatonin, such as anti-inflammatory and antioxidant actions, have also been observed. In this regard, although there are very few trials in humans, “it has been shown that, when administered as a coadjuvant in patients with various types of tumour, melatonin can help to increase survival and reduce the side-effects of chemotherapy”, he noted.
With respect to the cardiovascular and nervous systems, melatonin exerts a broad spectrum of action. As explained by Francesco Portaluppi, from the Hospital Universitario Sant’Anna de Ferrara (Italy), numerous beneficial effects of the action of this hormone on vascular and myocardial remodelling, ischaemia and blood pressure regulation, with possible positive impacts on hypertension and stroke, amongst other disorders, are known. In addition, melatonin has been shown to have a protective effect on tissues in the central nervous system.
As far as the administration of melatonin as a drug, which has gained in popularity recently, is concerned, Portaluppi does not recommend this in healthy people but notes its efficacy in the case of people suffering from chronodisruption provided it is prescribed medically. “This concept relates to dysfunctions in our biological clock caused by jet lag, shift work or getting little sleep for extended periods. It has a negative impact on psychological function and predisposes us to disease, therefore supplementary administration of melatonin helps to rebalance the system”, he explained.
Portaluppi is collaborating with the Information and Communications Technology Research Centre (AtlantTIC) at the University of Vigo in two studies in the field of chronobiology and chronotherapy applied to hypertension. “Together we have helped to gain a better understanding of the temporal aspects of blood pressure regulation and its pharmacological control in individuals suffering from different types of hypertension”, he noted.
Rüdiger Hardeland, from the University of Göttingen (Germany), explained that, although Alzheimer-related neurodegeneration affects the region of the central nervous system that controls the biological clock and melatonin secretion, exogenous administration of this hormone to patients suffering from this disease remains controversial. “Some authors have reported moderate improvements in memory, mood and so-called sundown syndrome, which is accompanied by increased restlessness and confusion at the end of the day. However, the variations between patients are marked, improvements in sleep disorders have not been confirmed and no opportunity to stop deterioration in advanced stages of the disease has arisen”, he explained.
With regard to the main questions that the scientific community still needs to answer in this field, Professor Hardeland stressed two, namely determining when melatonin treatment should be initiated on the basis of the genetic risk factors for each individual, and determining whether a daily dose in the afternoon is sufficient considering that the levels of this hormone diminish drastically at night in Alzheimer's patients.