Journal Title (Medline/Pubmed accepted abbreviation): Int J Sport Nutr Exerc Metab
Page numbers: 135-145
doi (if applicable): N/A
Background: Prolonged (> 1.5 hr), continuous, moderate to high intensity exercise performed in a fasted state affects both the innate and adaptive immune systems, creating a period of ~ 3 to 24 hours postexercise when athletes are vulnerable to infections, especially upper respiratory tract infection (URTI). Bovine colostrum, the first milk made after parturition, is a good source of carbohydrates, protein, fat, minerals, and growth and immune factors, and is being investigated as a nutritional supplement for its potential to enhance immune function. Results on the potential of bovine colostrum in sport nutrition are unclear, and only limited information is available on exercise-induced alterations in immune variables.
Hypothesis/purpose of study: The purpose of the study was to investigate the effect of bovine colostrum supplementation on several immune variables following short-term intense exercise in well-trained, glycogen-depleted athletes.
Subjects: Nine well-trained male athletes completed the study (mean age, 27.3 ± 4.5 yr; weight, 73.0 ± 5.7 kg; body mass index, 21.9 ± 1.6 kg/m2; maximal power output [Wmax], 364.4 ± 25.1 W). Training frequency ranged from 3 to 7 times/week, and training volume ranged from 5 to 12 hours/week.
Experimental design: Double-blind, placebo-controlled, crossover design
Treatments and protocol: Total study duration was 2 x 19 days, with a washout period of ~ 2.5 weeks. During the presupplementation period (first 7 days), subjects kept a log of dietary habits, training performance, and illness symptoms. The supplementation period was 10 days, and subjects consumed 12.5 g bovine colostrum or skim milk powder (placebo) twice a day mixed in a glass of cold milk or buttermilk. Following supplementation, subjects completed a glycogen-depletion trial (Day 17) and an endurance cycling trial (Day 18; 1.5 hours at 50% Wmax), to evoke a substantial amount of stress on the immune system. Blood samples were taken before the glycogen-depletion trial (T0), before (T1) and after (T2) the endurance trial, and ~ 22 hours after exercise cessation (T3), and were analyzed for neutrophil, lymphocyte, serum immunoglobulin, and cytokine counts.
Study results were consistent with the notion that intense exercise affects several markers of the immune system; however, 10 days of supplementation with bovine colostrum (25 g/day) did not have any different effects on the immune factors investigated compared with skim milk powder. Data from this study and others demonstrate that bovine colostrum supplementation does not offer benefit in preventing postexercise changes in immune variables after short-term intense exercise during periods of normal physical activity. However, the effects of bovine colostrum on intense exercise during periods of increased physical stress (eg, training camp) cannot be ruled out and warrant further study.