Bovine ColostrumFirst milk, spray dried · 4 claims

A 2016 meta-analysis pooled five trials and 152 participants, all in regular exercise training. Over 8–12 weeks colostrum reduced upper respiratory symptom days by 44% (rate ratio 0.56, 95% CI 0.43–0.72, p<0.001) and episodes by 38% (0.62, 0.40–0.99, p=0.04).

A later meta-analysis with 445 participants across 7 trials found infection risk reduced to a similar degree: RR 0.64 (95% CI 0.498–0.822, p<0.001). The effect was somewhat dependent on how long supplementation continued.

Two honest caveats from the authors themselves. Most of the individual included studies did not report significant effects — which they note actually reduces concern about publication bias. And the low precision of individual estimates means the finding needs an adequately powered trial to confirm it. That trial has not been done.

• MetaJones AW, March DS, Curtis F, Bridle C. Bovine colostrum supplementation and upper respiratory symptoms during exercise training BMC Sports Sci Med Rehabil 2016 · PMID 27462401 · PROSPERO CRD42015014925
• MetaBovine colostrum supplementation in prevention of upper respiratory tract infections: systematic review, meta-analysis and meta-regression 7 trials, 445 randomized participants · RR 0.64

A 2024 meta-analysis in Digestive Diseases and Sciences pooled randomised trials of bovine colostrum on the gut barrier in healthy athletes and in patients, searching to March 2022 and using weighted mean differences under a random-effects model.

This is the claim doing most of the work in current marketing — “gut health” is what colostrum is sold on. The evidence is one synthesis, on a surrogate measure, in mixed populations. That is a reasonable starting point and it is not the same as a demonstrated benefit you would feel.

• MetaBovine colostrum in increased intestinal permeability in healthy athletes and patients: a meta-analysis of randomized clinical trials Dig Dis Sci 2024;69(4):1345-1360 · doi 10.1007/s10620-023-08219-2

Colostrum is marketed on being rich in antibodies and growth factors. Reviewed against actual measurements, supplementation shows no or fairly low impact on serum immunoglobulins (IgA, IgG), lymphocytes, neutrophils or salivary IgA in athletes and physically active people.

Some work has found increased neutrophil and monocyte phagocytic and oxidative function. But the simple story — you drink the antibodies, your antibody levels rise — is not what the data show.

Worth holding alongside claim 01. The infection finding may well be real; the explanation offered for it mostly is not.

• RevSystematic review of bovine colostrum effects on immunoglobulins and immune cell measures No or fairly low impact on serum IgA, IgG, lymphocytes, neutrophils and salivary IgA

The World Anti-Doping Agency advises athletes against taking colostrum, on concern that it may raise plasma IGF-1. There is a further theoretical concern that IGF-1 elevation could stimulate malignancy in tissues expressing IGF-1 receptors.

The studies actually measuring this are small: 16 healthy males given 40 g acutely, then parallel trials of 20 g/day for four weeks (n=10 per arm) and twelve weeks (n=25 versus 29). Small enough that neither reassurance nor alarm is well supported.

The practical position is simple regardless of what the IGF-1 data eventually shows. If you compete under a code that follows WADA guidance, the governing body has already told you not to.

• RevWADA position and plasma IGF-1 trial designs, as reported in the colostrum literature 40 g acute; 20 g/day for 4 and 12 weeks