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Limited evidenceImmunity

Bovine Colostrum

Bovine colostrum reliably raises salivary IgA in trained people, but the meta-analytic evidence that this translates into fewer infections, better gut integrity or improved performance is weak. It is an expensive supplement resting largely on surrogate markers.

What the science says

  • Immune markers in athletes Moderate evidence

    A 2020 systematic review and meta-analysis of trials in trained and physically active people found bovine colostrum consistently increased salivary IgA concentration compared with placebo, while effects on other immune outcomes — circulating immunoglobulins, cytokines, leukocyte counts — were inconsistent or null. Higher salivary IgA is a surrogate, not an outcome.

  • Reducing upper respiratory infections Limited evidence

    Individual trials point in different directions: a randomized trial in highly trained cyclists using 10 g/day for 5 weeks found changes in immune variables but no consistent reduction in illness, and the pooled athlete literature is too heterogeneous and too small to establish a protective effect. Claims of fewer sick days are not well supported.

  • Gut permeability and exercise performance Limited evidence

    Small crossover studies suggest colostrum attenuates the rise in intestinal permeability caused by heat stress or NSAIDs, but sample sizes are typically under 20 and results are mixed. Ergogenic effects on strength, sprint or endurance performance have not been demonstrated in adequately powered trials.

Dosage & safety

Studied doseTrials have used 10-60 g/day of bovine colostrum powder, most commonly 20 g/day for 4-8 weeks; low-dose immune trials use 10 g/day. Products vary enormously in IgG content (typically 10-40%), which is the only meaningful basis for comparing them — total powder grams tells you little.
SafetyGenerally well tolerated; mild GI symptoms — bloating, nausea, loose stools — are the usual complaints, partly from lactose content. Contraindicated in cow's-milk protein allergy, and low-lactose forms should be chosen by people with lactose intolerance. It is a milk product, so theoretical risk of transmitting bovine pathogens exists if sourcing and pasteurisation are poor; buy from suppliers with documented testing. Important regulatory note: colostrum contains IGF-1 and growth factors, and WADA has explicitly warned athletes that colostrum is not prohibited but may contain enough IGF-1 to affect a doping test — several sport bodies advise against its use for that reason. Not suitable for vegans.

Scientific references

Where to buy

Swanson Vitamins, Grass-Fed Bovine Colostrum Powder, Unflavored, 2.12 oz (60 g)

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