Benefits
Gut barrier function during hard physical exertion
Small trials disagree here. In two crossover studies, colostrum blunted the rise in a urinary gut-permeability marker after hard exercise, and athletes on 1 gram a day for 20 days had lower permeability and stool zonulin than on placebo. A pooled analysis of 10 trials found a lower marker, but results varied widely and a blood marker of gut cell damage did not change. In runners, 60 grams a day for 8 weeks raised the marker.
Immune support in active adults
Colostrum supplies antibodies and lactoferrin. A pooled analysis of five trials in 152 exercising adults found 44% fewer days with upper respiratory symptoms, though four of the five trials were at moderate or high risk of bias. In a trial of 0.5 to 1 gram a day in university students, the whole group did not differ from placebo; only medical students with hospital exposure had fewer symptom days. Antibody levels changed little.
Leg strength and jump power, tested against protein controls
Small double-blind trials compared colostrum with protein controls. In 40 older adults lifting weights, 60 g a day for 8 weeks raised leg press strength more than whey (24 vs 8 kg); bench press and lean mass rose equally on both. In 29 rugby players, 38 g a day gave a small vertical jump gain but no strength gain over soy. In 18 soccer players, 3.2 g a day kept jump height up better after a muscle-damaging drill (partly seller-funded).
Mechanism of action
Immunoglobulins in the gut
IgG is the main immunoglobulin in bovine colostrum. Taken by mouth, it is proposed to act inside the gut, binding microbes and toxins, rather than in the bloodstream. This is a proposed mechanism from laboratory work; a pooled analysis of trials in trained adults found little or no change in blood immunoglobulins, white blood cell counts or saliva IgA.
Growth factors and gut epithelial integrity
Bovine colostrum contains growth factors including IGF-1, TGF-α, TGF-β and EGF. In human colon cell lines, colostrum raised heat shock protein 70 (HSP70), reduced heat-induced cell death and limited the fall in epithelial resistance, and the HSP70 rise was blocked by an antibody against the EGF receptor. These are laboratory findings. In older adults, 60 grams a day for 8 weeks did not change blood IGF-1.
Lactoferrin
Lactoferrin is an iron-binding protein with antimicrobial properties. In laboratory studies it limits bacterial growth by holding on to iron and can disrupt microbial membranes. The human colostrum trials cited here measured gut permeability, symptoms and performance rather than lactoferrin activity directly.
Other bioactive proteins and peptides
Lactoperoxidase, lysozyme and proline-rich polypeptides are other colostrum components proposed to add antimicrobial and immune-modulating activity. Evidence for these effects comes from laboratory work, not from the human trials cited here.
Clinical trials
Double-blind, placebo-controlled crossover trial in 12 volunteers given 14 days of bovine colostrum or placebo before standardized heavy exercise, with gut permeability measured by the 5-hour urinary lactulose/rhamnose ratio; the paper also includes cell-culture work. (Marchbank et al. 2011, Am J Physiol Gastrointest Liver Physiol)
12 volunteers in a crossover design.
The standardized workload raised core temperature by a mean of 1.4°C in both arms. On placebo the permeability ratio rose 2.5-fold (0.38 to 0.92); on colostrum the rise was truncated by 80% (0.38 to 0.49). The abstract does not state the dose. The heat shock protein and EGF receptor findings come from the paper's cell-culture arm, not from the volunteers.
Systematic review and meta-analysis of 5 randomized controlled trials in 152 healthy adults in regular exercise training, comparing oral bovine colostrum with placebo over 8 to 12 weeks. (Jones et al. 2016, BMC Sports Sci Med Rehabil)
152 healthy, physically active adults.
Colostrum was linked to 44% fewer days with upper respiratory symptoms (rate ratio 0.56, 95% CI 0.43 to 0.72) and 38% fewer episodes (rate ratio 0.62, 95% CI 0.40 to 0.99). Four of the five trials were judged at moderate or high risk of bias, most did not find significant effects on their own, and there were too few data to pool symptom duration. The authors called for a larger, well-designed trial.
Randomized, triple-blind trial in 271 enrolled medical and health science students given 500 mg of bovine colostrum twice daily for 15 days, then once daily for 30 days, plus a 7-day course from day 87, or a whey placebo, with symptoms self-reported online over 107 days; 158 were analyzed. (Baśkiewicz-Hałasa et al. 2023, Nutrients)
158 analyzed healthy medical and health science university students (271 enrolled).
Across all students over 107 days, symptom days (p = 0.21) and severity (p = 0.31) did not differ significantly. Medical students attending hospital classes had fewer and milder symptom days on colostrum, and all students had fewer symptom days in the final period after the second course. The analysis kept only students who completed at least 85 surveys and excluded 21 with very high symptom scores, and an author receives payment from the manufacturer.
Systematic review and meta-analysis of 10 randomized clinical trials in healthy athletes and patient groups, assessing bovine colostrum against urinary lactulose/rhamnose and lactulose/mannitol ratios and plasma I-FABP. (Hajihashemi et al. 2024, Dig Dis Sci)
Healthy athletes and patients across 10 pooled trials.
The pooled 5-hour lactulose/rhamnose ratio fell (mean difference -0.24, 95% CI -0.43 to -0.04), as did the lactulose/mannitol ratio (-0.01). Heterogeneity for the lactulose/rhamnose result was 99%, meaning the trials did not agree with one another, and the blood marker of intestinal cell damage, I-FABP, showed no difference. The authors called for more trials varying quality, dose and duration.
Trial in 30 healthy men running three times a week for 8 weeks: 13 served as unsupplemented controls and the rest were randomly assigned, double-blind, to 60 g/day of bovine colostrum (9) or whey protein (8), with gut permeability measured by the urinary lactulose/rhamnose ratio. (Buckley et al. 2009, Nutrients)
30 healthy adult men running three times a week (9 on colostrum).
The permeability ratio rose 251% on colostrum, versus 21% on whey and a 7% fall in controls, so the marker moved the wrong way at this dose. The authors suggest the rise may reflect more transport of large molecules rather than damage.
Double-blind randomized trial in 40 older adults (15 men, 25 women, about 59 years) given 60 g/day of bovine colostrum or whey protein for 8 weeks while resistance training 3 days a week. (Duff et al. 2014, Int J Sport Nutr Exerc Metab)
40 older adults in a resistance training program.
Leg press strength rose more on colostrum than on whey (24 vs 8 kg, p < .01). Bench press strength, muscle thickness, lean tissue mass and cognitive scores improved in both groups with no difference between them, and plasma IGF-1 and CRP did not change.
Double-blind randomized trial in 29 club rugby players (three women) given 38 g/day of bovine colostrum or soy protein for 8 weeks during the competitive season. (Mizelman et al. 2026, Eur J Appl Physiol)
29 club-level rugby players.
Vertical jump rose slightly more on colostrum (+1.0 cm vs -0.5 cm on soy, p = 0.0023). Upper and lower body strength, aerobic power, body composition, salivary IgA and inflammatory markers did not differ from soy, and reported illness was unaffected.