Dutch researchers conclude that a diet containing tryptophan-enriched whey proteins could improve the ability to cope with stress in healthy but stress-vulnerable subjects. A lack of serotonin in the brain has been linked to depression and reduced ability to cope with stress. Serotonin is synthesized from tryptophan and its concentration increases with the intake of a meal rich in carbohydrates and low in protein. Dutch researchers now report the discovery that a whey protein enriched with alpha-lactalbumin (Borculo Domo Ingredients, Borculo, Netherlands) is highly effective in increasing tryptophan levels in the brain and improving the ability to cope with stress among stress-vulnerable people. Their double-blind, placebo-controlled study involved 29 university students who were easily stressed and 29 students who were relatively immune to stress. The students were given a chocolate-flavoured drink containing either the whey protein or a casein placebo and were then exposed to a highly stressful arithmetic test which has been found to induce significant psychological and physiologic stress. Blood analysis showed a significantly higher concentration of tryptophan (relative to other large neutral amino acids) in the subjects who had consumed the fortified whey protein than in those who had consumed the casein drink. The stress-vulnerable students who had consumed the whey protein also showed an improvement in mood and a reduced cortisol stress response when compared to the stress-vulnerable students who had consumed the casein drink.
Markus, C. Rob, et al. The bovine protein alpha-lactalbumin increases the plasma ratio of tryptophan to the other large neutral amino acids, and in vulnerable subjects raises brain serotonin activity, reduces cortisol concentration, and improves mood under stress. American Journal of Clinical Nutrition, Vol. 71, June 2000, pp. 1536-44