IL CIOCCOLATO CI RENDE DAVVERO DI BUON UMORE?
Il cioccolato è un alimento derivato dai semi della pianta del cacao, il cui nome botanico è Theobroma cacao. È diffuso e ampiamente consumato nel mondo intero. È stato definito “cibo degli dei” e gli sono state attribuite proprietà benefiche sull’umore delle persone. Tra i vari componenti del cioccolato spicca la serotonina, neurotrasmettitore che gioca un ruolo chiave nel trattamento della depressione.
Fra tanti alimenti che contengono serotonina o il suo precursore, l’aminoacido essenziale triptofano, solo al cioccolato viene attribuito il merito di migliorare l’umore. C’è qualche evidenza?
Serotonin or 5-hydroxytryptamine (5-HT) is a monoamine neurotransmitter Biochemically derived from tryptophan
Serotonin is primarily found in enterochromaffin cells in the gastrointestinal (GI) tract (where is located almost 90% of the human body total serotonin) and platelets. The reminder is synthesized in serotonergic neurons of the central nervous system (CNS). In the CNS it has various functions such as regulation of appetite and sleep and some cognitive functions including memory and learning. Is popularly thought to be a contributor to feelings of well-being and happiness and modulation of serotonin at synapses. It is thought to be a major action of several classes of pharmacological antidepressants.
- The synthesis of brain 5-HT depends on two main variables, the neuronal concentration of its precursor, tryptophan (Trp), and the activity of its ratelimiting enzyme, tryptophan hydroxylase (TPH; converts tryptophan into 5-hydroxytryptophan)
- Tryptophan is competing with other amino acids like valine, isoleucine and leucine to enter the brain therefore the ratio between tryptophan and those other amino acid is important to determine the availability of the precursor for brain serotonin synthesis.
- The biochemical process that leads to the synthesis of serotonin is the following:
Anyway it may occur in those of us who experience particular life events and difficulties that Tryptophan availability to the brain might be compromised to some extent and this might lead to clinical depression only in the presence of other predisposing factors.
EFFECTS OF FOOD CONTENT
Our diets affects the levels of serotonin. An increase in the ratio of tryptophan to phenylalanine and leucine will increase serotonin levels:
- Fruits with a good ratio include dates, papayas and bananas.
- Food with a lower ratio inhibit the production of serotonin. These include whole wheat and rye bread.
- Myoinositol, a carbocyclic polyol present in many foods, is known to play a role in serotonin modulation. (Muscles use many of the amino acids except tryptophan, allowing more muscular individuals to produce more serotonin.)
- Research also suggests eating a diet rich in carbohydrates and low in protein will increase serotonin by secreting insulin, which helps in amino acid competition. However, increasing insulin for a long period may trigger the onset of insulin resistance, obesity, type 2 diabetes and lower serotonin levels.
- Some kind of fish (tuna and codfish), meat (beef, chicken and pork) and cheese (or products derived from milk in general) are also rich in tryptophan but during the process of preparation and conservation of these foods most of the tryptophan could get lost.
- Cocoa is very rich in tryptophan and serotonin and on the contrary of what happens for other foods high levels of them are still found in chocolate.
ARE THERE CONNECTIONS BETWEEN CHOCOLATE CONSUMPTIONS AND GOOD MOOD?
A rich cultural tradition links chocolate consumption with putative mood benefits. Potential means by which chocolate may mediate mood benefits have been described but no scientific evidence has been found. There are many articles on internet that relate somehow chocolate to good mood but, for example, the MeSH terms “cocoa” and “mood” yield only 25 PubMed results. More important is that, despite the fact that those studies don’t come to an agreement or a common conclusion, none of them managed to prove the existence of any sort of relationship between cocoa and good mood.
Some results of the studies
- Chocolate can provide its own hedonistic reward by satisfying cravings but, when consumed as a comfort eating or emotional eating strategy, is more likely to be associated with prolongation rather than cessation of a dysphoric mood. Mood state effects of chocolate.2006
- An Analysis on a sample of 1018 adults (including men and women) examined the relationship of chocolate consumption to mood. Higher CES-D (Epidemiologic Studies Depression Scale) depression scores were associated with greater chocolate consumption. Whether there is a causal connection, and if so in which direction, is a matter for future prospective study. Mood food: chocolate and depressive symptoms in a cross-sectional analysis.2010
Non ci sono attualmente prove scientifiche che leghino il “buonumore” al consumo di cioccolato. In alcuni casi l’aumentato consumo di cioccolato è addirittura correlato a stati depressivi, ma si ignora il significato di tale relazione (si ignora quale sia la causa e quale la conseguenza). Gli effetti benefici dell’assunzione di cioccolato sono, a quanto pare, più legati al gusto del cioccolato che alla sua composizione chimica: il cioccolato “senza sapore” pare non avere effetto. Questo può indurci a pensare che alla base della credenza comune che il cioccolato provochi buonumore possa esserci una componente di autosuggestione responsabile di una sorta di effetto placebo.