More recently, research into α-lactalbumin has revealed that this whey-derived protein has the highest Trp content of all proteins found in food and therefore is added to infant milk formulas ( Reference Heine, Radke and Wutzke 7 ). Another example is the treatment of maize with alkali by various cultures in America, which enhances the bioavailability of Trp ( Reference Katz, Hediger and Valleroy 5, Reference Morris and Sands 6 ). For instance, Neolithic Mesopotamia-cultivated chickpeas contained more Trp than wild varieties ( Reference Kerem, Lev-Yadun and Gopher 4 ). Furthermore, sometimes unknowingly, the Trp content of food has been increased. Accordingly, high-Trp-containing foods (for example, chicken, soyabeans, cereals, tuna, nuts and bananas) are presented on the Internet as food to improve mood. Therefore, Trp levels in food appear to be an essential link in the relationship between food intake and our mood state. The serotonin precursor Trp is an essential amino acid that in mammals can only be derived from food ( Reference Wurtman, Hefti and Melamed 3 ). To improve mood by other means, food with high tryptophan (Trp) availability and modest monoamine reuptake and MAO-A inhibition functional profile may be effective. Hence, whereas monoamine reuptake inhibitors and MAO-A inhibitors improve mood, particularly in individuals with a low mood state, their use is not without risks. A major risk is the serotonin syndrome too high levels of serotonin are toxic. However, these agents are also associated with substantial side effects. In addition to monoamine reuptake inhibitors, also drugs that inhibit the breakdown of monoamines are used to improve mood, particularly monoamine oxidase A (MAO-A) inhibitors.

Furthermore, triple monoamine reuptake inhibition corresponds to the function of cocaine, which is a powerful psychostimulant with abuse potential. For instance, at a young age these drugs may affect brain development and increase suicide ( Reference Olivier, Chan and Snoeren 2 ). Whereas antidepressant drugs are considered as healthy drugs, their uncontrolled intake is not without risks. To a limited extend these agents also inhibit dopamine reuptake. As such, tricyclic antidepressants (inhibiting serotonin and noradrenaline reuptake) and selective serotonin reuptake inhibitors (SSRI) are frequently prescribed drugs in the treatment of these disorders. The monoamine systems are strongly tied to stress resilience and the (patho)physiology of mood and mood disorders. Yet, whereas pharmacological manipulations have been abundantly applied, surprisingly little is known about the effects of food on mood and cognition. Thus, the exploitation of resilience or mood/cognition-enhancing food is of extreme value. They are characterised by low mood states and cognitive impairments such as reduced learning and memory ( 1 ). Stress-related mental disorders such as mood or anxiety disorders are the most prevalent (10 to 25 % women and 5 to 12 % men are being diagnosed each year ( 1 )), and burdensome, psychiatric disorders. Yet, even when food is abundantly available, food could also be used as a powerful tool to increase mental well-being. 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.įood is a primary requirement to live.

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. 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. This relationship is found for both healthy and vulnerable subjects. 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. Here we discuss the effects of high- or low-tryptophan-containing 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. 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. However, side-effects have been reported for these drugs. 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.

Exces de serotonina