Food-derived serotonergic modulators: effects on mood and cognition

Abstract

The most frequently described drugs in the treatment of mood disorders are selective serotonin reuptake and monoamine oxidase (MAO) inhibitors, enhancing serotonin levels in the brain. However, side-effects have been reported for these drugs. Because serotonin levels in the brain are dependent on the availability of the food-derived precursor tryptophan, foods such as chicken, soyabeans, cereals, tuna, nuts and bananas may serve as an alternative to improve mood and cognition. Here we discuss the effects of high-or low-tryptophancontaining food, as well as plant extracts with a modest monoamine reuptake and MAO-A inhibition functional profile, on mood and cognition in healthy and vulnerable human subjects and rodents. Together the studies suggest that there is an inverted U-shaped curve for plasma tryptophan levels, with low and too high tryptophan levels impairing cognition, and moderate to high tryptophan levels improving cognition. This relationship is found for both healthy and vulnerable subjects. Whereas this relationship may also exist for mood, the inverted U-shaped curve for plasma tryptophan levels and mood may be based on different tryptophan concentrations in healthy v. vulnerable individuals. Animal studies are emerging and allow further understanding of effects and the mode of action of food-derived serotonergic components on mood, cognition and mechanisms. Ultimately, insight into the concentrations of tryptophan and other serotonergic components in food having beneficial effects on mood and cognition in healthy, but particularly vulnerable, subjects may support well-being in our highly demanding society.

The role of lateral habenula–dorsal raphe nucleus circuits in higher brain functions and psychiatric illness

“…The role of 5-HT in relation to cognition is supported by the importance of appropriate levels of tryptophan, the biochemical precursor of 5-HT, for normal cognitive functioning [58,59] and the cognitive and emotional consequences of tryptophan depletion in genetically susceptible individuals [60,61].…”

Evolution of tryptophan and its foremost metabolites’ concentrations in milk and fermented dairy products

“…TRP is rapidly absorbed by the gastro-intestinal (GI) tract and crosses the blood-brain barrier (BBB), in turn acting as a precursor of serotonin synthesis [11]. Indeed, TRP is used as supplement precisely to increase serotonin (5-HT) cerebral concentrations and, thus, modulate sleep and mood [12]. Serotonin has been suggested to play a role also in the GI system, by mediating motor activity, secretion processes, and visceral sensitivity.…”

How to measure mood in nutrition research

“…Moreover, the dose -response relationships to tryptophan for cognitive functioning and for mood appear to be different, and mediated by the prior neurochemical state of the brain (78) , again raising the question of whether tryptophan sometimes improves mood by improving cognitive efficiency.…”