The December Nutrition Society Paper of the Month is from Nutrition Research Reviews and is entitled ‘Food-derived serotonergic modulators: effects on mood and cognition’

Food is a primary requirement to live. Yet, in Western societies where food is abundantly available, food could also be used as a powerful tool to increase mental well-being. Stress-related mental disorders like mood or anxiety disorders are the most prevalent and burdensome psychiatric disorders. They are characterized by low mood states and cognitive impairments like reduced learning and memory. Thus, the exploitation of resilience or mood/cognition enhancing food is of extreme value.

According to the world-wide web, high tryptophan (Trp) containing foods (e.g. chicken, soybeans, cereals, tuna, nuts, and bananas) improve mood. Trp is an essential amino acid and a precursor of serotonin, a monoamine that plays a central role in the regulation of emotion, mood and cognition. It is hypothesized that in mood disorders like depression central serotonin levels are low. Although ‘Trp-containing food for mood’ appears as an attractive concept to build resilience, it is likely that there is a delicate balance between Trp levels in food and optimal effects on mood and cognition, and that this delicate balance is influenced by the serotonergic state of the individual. Furthermore, while there is a correlation between high Trp levels in food and mood improvement, it is not as straightforward such that eating a bunch of bananas each day will help you get a better mood.

Hence, this review provides an overview of the effects of varying levels of food-derived Trp on mood and cognition in healthy individuals, and individuals at risk for mood disorders. We also discuss the effects of plant extracts with a modest ‘antidepressant’ functional profile.

Together the studies suggest that there is an inverted U-shaped curve for plasma Trp levels with low and too high Trp levels impairing cognition, and moderate to high Trp 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 Trp levels and mood may be based on different Trp concentrations in healthy versus vulnerable individuals. That is, there is a much more profound decrease in mood of vulnerable subjects compared to healthy subjects in the lower brain Trp range.

When brain Trp levels are in the optimum range, mood in vulnerable subjects is comparable with mood in healthy subjects. And when Trp levels are further elevated, positive mood effects are detected with small increases in vulnerable healthy individuals, and only with large increases in healthy subjects.  Finally, mood in both healthy and vulnerable subjects is negatively affected when Trp levels are excessively high.

Ultimately, insight in the concentrations of Trp and other serotonergic components in food having beneficial effects on mood and cognition in healthy, but particularly vulnerable, subjects may help the nutrition industry to adapt food to support our mood and cognition.

This paper is freely available for one month via the following link: journals.cambridge.org/ns/dec13

Nutrition Society Paper of the Month

Each month a paper is selected by one of the Editors of the five Nutrition Society Publications (British Journal of Nutrition, Public Health Nutrition, Nutrition Research Reviews, Proceedings of the Nutrition Society and Journal of Nutritional Science). This paper is freely available for one month.