The effects of a diet enriched with α-lactalbumin on mood and cortisol response in unmedicated recovered depressed subjects and controls

• Published in: British journal of nutrition 2005-09, Vol.94 (3), p.415-422
• Main Authors: Merens, Wendelien, Booij, Linda, Markus, Rob, Zitman, Frans G., Onkenhout, Willem, Van der Does, A.J. Willem
• Format: Article
• Language: English
• Subjects: Adult; Affect; Amino Acids - blood; Analysis of Variance; antidepressants; Biological and medical sciences; brain; Case-Control Studies; Cortisol; Cross-Over Studies; Depression; Depression - diet therapy; Depression - metabolism; Depression - psychology; Diet; Dietary Supplements; Double-Blind Method; Feeding. Feeding behavior; Female; food composition; fortified foods; Fundamental and applied biological sciences. Psychology; hormone secretion; Humans; Hydrocortisone - analysis; Hydrocortisone - blood; lactalbumin; Lactalbumin - administration & dosage; Lactalbumin - blood; Male; neurotransmitters; Saliva - chemistry; Serotonin; Statistics, Nonparametric; stress response; tryptophan; Tryptophan - blood; Vertebrates: anatomy and physiology, studies on body, several organs or systems; α-Lactalbumin
• ISSN: 0007-1145; 1475-2662
• DOI: 10.1079/BJN20051492

α-Lactalbumin is a tryptophan-rich protein fraction. A diet enriched with α-lactalbumin increases the ratio of tryptophan to the other large neutral amino acids, which may in turn increase brain serotonin content. In stress-vulnerable individuals, α-lactalbumin improved mood and attenuated the cortisol response after experimental stress. The aim of the present study was to investigate the effects of an α-lactalbumin-enriched diet on mood and stress response in recovered depressed subjects and healthy controls. Forty-three subjects (twenty-three recovered depressed and twenty healthy subjects) received α-lactalbumin and casein (placebo) on separate days, in a double-blind randomised crossover design. On both occasions, subjects underwent a stress test (an unsolvable mental arithmetic task with loud noise). The stress test affected mood in both conditions. Although the α-lactalbumin diet led to the expected rises in tryptophan and tryptophan:large neutral amino acids ratio, only minimal effects were found on mood and cortisol response to experimental stress. The results were the same for recovered depressed patients and controls. A 1 d diet enriched with α-lactalbumin is not sufficient to prevent a stress-induced mood deterioration or a cortisol response in unmedicated, recovered depressed subjects. Future studies may investigate the effects of longer-term diets or may investigate different samples (e.g. medicated patients).