The effects of nutrients on mood
Abstract
A recent major theory was that a meal high in carbohydrate increased the rate that
tryptophan enters the brain, leading to an increase in the level of the neurotransmitter
serotonin that modulates mood. Although such a mechanism may be important under
laboratory conditions it is unlikely to be of significance following the eating of any
typical meal. As little as 2–4% of the calories of a meal as protein will prevent an
increased availability of tryptophan. Arguably the food with the greatest impact on
mood is chocolate. Those who crave chocolate tend to do so when they feel
emotionally low. There have been a series of suggestions that chocolate’s mood
elevating properties reflect ‘drug-like’ constituents including anandamines, caffeine,
phenylethylamine and magnesium. However, the levels of these substances are so
low as to preclude such influences. As all palatable foods stimulate endorphin release
in the brain this is the most likely mechanism to account for the elevation of mood. A
deficiency of many vitamins is associated with psychological symptoms. In some
elderly patients folate deficiency is associated with depression. In four double-blind
studies an improvement in thiamine status was associated with improved mood. Iron
deficiency anaemia is common, particularly in women, and is associated with apathy,
depression and rapid fatigue when exercising.