title: Breakfast high in whey protein or carbohydrates improves coping with workload in healthy subjects.
abstract: Dietary components may affect brain function and influence behaviour by inducing the synthesis of neurotransmitters. The aim of the present study was to examine the influence of consumption of a whey protein-containing breakfast drink v. a carbohydrate drink v. control on subjective and physiological responses to mental workload in simulated work. In a randomised cross-over design, ten healthy subjects (seven women, median age 26 years, median BMI 23 kg/m(2)) participated in a single-blinded, placebo-controlled study. The subjects performed demanding work-like tasks after having a breakfast drink high in protein (HP) or high in carbohydrate (HC) or a control drink on separate sessions. Subjective states were assessed using the NASA Task Load Index (NASA-TLX), the Karolinska sleepiness scale (KSS) and the modified Profile of Mood States. Heart rate was recorded during task performance. The ratio of plasma tryptophan (Trp) to the sum of the other large neutral amino acids (LNAA) and salivary cortisol were also analysed. The plasma Trp:LNAA ratio was 30 % higher after the test drinks HP (median 0·13 (μmol/l)/(μmol/l)) and HC (median 0·13 (μmol/l)/(μmol/l)) than after the control drink (median 0·10 (μmol/l)/(μmol/l)). The increase in heart rate was smaller after the HP (median 2·7 beats/min) and HC (median 1·9 beats/min) drinks when compared with the control drink (median 7·2 beats/min) during task performance. Subjective sleepiness was reduced more after the HC drink (median KSS - 1·5) than after the control drink (median KSS - 0·5). There were no significant differences between the breakfast types in the NASA-TLX index, cortisol levels or task performance. We conclude that a breakfast drink high in whey protein or carbohydrates may improve coping with mental tasks in healthy subjects.
authors.affiliation: Institute of Biomedicine, Medical Nutrition Physiology, Pharmacology, University of Helsinki, PO Box 63, Helsinki FIN-00014, Finland.
authors.forename: Nora
authors.initials: N
authors.lastname: Sihvola
authors.forename: Riitta
authors.initials: R
authors.lastname: Korpela
authors.forename: Andreas
authors.initials: A
authors.lastname: Henelius
authors.forename: Anu
authors.initials: A
authors.lastname: Holm
authors.forename: Minna
authors.initials: M
authors.lastname: Huotilainen
authors.forename: Kiti
authors.initials: K
authors.lastname: Müller
authors.forename: Tuija
authors.initials: T
authors.lastname: Poussa
authors.forename: Kati
authors.initials: K
authors.lastname: Pettersson
authors.forename: Anu
authors.initials: A
authors.lastname: Turpeinen
authors.forename: Katri
authors.initials: K
authors.lastname: Peuhkuri
mesh_terms: D000328:Adult; D000596:Amino Acids / Q000097:blood*; D021542:Amino Acids, Neutral / Q000097:blood; D001921:Brain / Q000187:drug effects; D062408:Breakfast / Q000502:physiology*; D018592:Cross-Over Studies; D004032:Diet; D004040:Dietary Carbohydrates / Q000494:pharmacology*; D004311:Double-Blind Method; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism; D008297:Male; D008606:Mental Processes / Q000502:physiology*; D008894:Milk Proteins / Q000494:pharmacology*; D012016:Reference Values; D012463:Saliva / Q000378:metabolism; D016037:Single-Blind Method; D012890:Sleep / Q000187:drug effects; D012894:Sleep Stages / Q000187:drug effects*; D014364:Tryptophan / Q000097:blood; D000067816:Whey Proteins; D016526:Workload; D055815:Young Adult
chemical_list: D000596:Amino Acids; D021542:Amino Acids, Neutral; D004040:Dietary Carbohydrates; D008894:Milk Proteins; D000067816:Whey Proteins; D014364:Tryptophan; D006854:Hydrocortisone