Beulens Joline W J, Bindels Jacques G, de Graaf Cees, Alles Martine S, Wouters-Wesseling Wendeline
Department of Clinical Nutrition and Diets, Numico Research BV, Wageningen, The Netherlands.
Physiol Behav. 2004 Jun;81(4):585-93. doi: 10.1016/j.physbeh.2004.02.027.
Brain serotonin influences food intake and mood. It is synthesised from tryptophan (Trp) of which uptake in the brain is dependent on plasma ratio of tryptophan to the sum of other large neutral amino acids (Trp-LNAA). A carbohydrate-rich diet increases this ratio, whereas a protein-rich diet decreases it. Yet, if the protein source is alpha-lactalbumin the ratio increases. It is, however, unknown whether this also happens in the context of a regular diet (15% protein). We studied the effect of an alpha-lactalbumin supplement combined with regular diet on plasma Trp-LNAA ratio, serum prolactin (marker of serotonin synthesis), food intake, appetite, macronutrient preference and mood. Eighteen healthy males participated in a double-blind, randomised, placebo-controlled, crossover study. One hour after breakfast they received a drink containing alpha-lactalbumin and carbohydrates (AS) or carbohydrates (PS) only. Plasma Trp-LNAA ratio, serum prolactin, food intake, appetite, macronutrient preference and mood were assessed before and 90 min after consumption of the supplement. Changes of plasma Trp-LNAA ratio differed (P<.001) between both supplements, increasing by 16% after AS and decreasing by 17% after PS. Decrease of serum prolactin was slightly smaller after AS than after PS (P=.083). Appetite, food intake, macronutrient preference or mood did not differ between supplements. We conclude that an alpha-lactalbumin-enriched supplement combined with a regular diet increases plasma Trp-LNAA ratio and may influence serum prolactin, but we could not demonstrate effects on appetite, food intake, macronutrient preference and mood.
大脑中的血清素会影响食物摄入和情绪。它由色氨酸（Trp）合成，而大脑对色氨酸的摄取取决于色氨酸与其他大型中性氨基酸总和（Trp-LNAA）的血浆比例。富含碳水化合物的饮食会提高这一比例，而富含蛋白质的饮食则会降低该比例。然而，如果蛋白质来源是α-乳白蛋白，该比例会升高。不过，在常规饮食（15%蛋白质）的情况下是否也是如此尚不清楚。我们研究了α-乳白蛋白补充剂与常规饮食相结合对血浆Trp-LNAA比例、血清催乳素（血清素合成的标志物）、食物摄入量、食欲、宏量营养素偏好和情绪的影响。18名健康男性参与了一项双盲、随机、安慰剂对照的交叉研究。早餐后1小时，他们分别饮用含有α-乳白蛋白和碳水化合物的饮料（AS）或仅含碳水化合物的饮料（PS）。在补充剂饮用前和饮用后90分钟评估血浆Trp-LNAA比例、血清催乳素、食物摄入量、食欲、宏量营养素偏好和情绪。两种补充剂之间血浆Trp-LNAA比例的变化存在差异（P<0.001），AS后升高了16%，PS后降低了17%。AS后血清催乳素的下降幅度略小于PS后（P=0.083）。补充剂之间的食欲、食物摄入量、宏量营养素偏好或情绪没有差异。我们得出结论，富含α-乳白蛋白的补充剂与常规饮食相结合会提高血浆Trp-LNAA比例，并可能影响血清催乳素，但我们未能证明其对食欲、食物摄入量、宏量营养素偏好和情绪有影响。
