Evidence explainerBovine colostrum

Colostrum Supplements: What the Trials Show for Gut, Immunity and Exercise

Bovine colostrum is the trend powder of the year. The trials are small and mixed: a gut-permeability signal at low doses, the opposite result at a high dose, fewer self-reported colds in athletes, and little change in immune blood markers or strength.

By Kymata Labs EditorialPublished October 12, 2026Last reviewed October 12, 2026

Medical review pending. Written by Kymata Labs Editorial from the studies cited below; a credentialed clinician has not reviewed it yet. Educational only, not medical advice.

Key takeaways

  • A 2024 meta-analysis of 10 trials found bovine colostrum lowered gut-permeability test ratios, but heterogeneity was very high and the authors asked for better trials [1].
  • One trial at 500 mg/day for 20 days improved gut permeability in 16 athletes, while another at 60 g/day for 8 weeks made it worse in runners [2][3].
  • In exercising adults, a 2016 meta-analysis of 5 trials (152 people) found fewer days with upper respiratory symptoms, but most trials had moderate or high risk of bias [4].
  • A 2020 meta-analysis of 10 trials found no or fairly low effect on blood and saliva immune markers [6].
  • In 29 rugby players, 38 g/day for 8 weeks improved vertical jump by about 1 cm but not strength, aerobic fitness, body composition or illness [7].

Safety at a glance

From our Bovine colostrum monograph. Published interactions and cautions only, each with its source.

Who should be careful

  • Milk allergy. Colostrum is cow's milk. People with cow's milk protein allergy should avoid it.[6]
  • Medicines. No published drug interactions for bovine colostrum were found in our sources. That is an absence of data, not proof of safety with every medicine.[1][6]
  • Children and older adults. A systematic review found conflicting results in children and little evidence in older adults.[6]
  • High doses and gut permeability. One trial at 60 g/day during running training found gut permeability increased rather than decreased.[5]

Full Bovine colostrum safety section

The evidence, graded

Pulled from our monograph evidence tables. Grades follow our evidence-grading policy.

Scorecard: what improved and what did not

Arrows are from your point of view as the person taking it: ↑ means the outcome improved, ↓ means it got worse, ↔ means no clear difference from the comparison group. Grades follow our evidence policy and reflect small, mostly short trials [1][6]. Most trials compared colostrum with whey or soy protein, not an inert placebo [2][3][5][7]:

  • ↑ Gut permeability tests improved in athletes at peak training, 500 mg/day for 20 days, grade C [2].
  • ↓ Gut permeability worsened (rose) during running training, 60 g/day for 8 weeks, grade C [3].
  • ↑ Fewer men reported upper respiratory symptoms, 60 g/day for 8 weeks, grade C [5].
  • ↔ Blood and saliva immune markers across 10 trials in active people, grade C [6].
  • ↔ Strength, aerobic power and body composition in rugby players, 38 g/day for 8 weeks; ↑ jump height by about 1 cm, grade D [7].

Gut permeability: a signal, with one trial pointing the other way

The most-cited trial gave 16 athletes in peak training 500 mg of colostrum or whey placebo for 20 days [2]. Lactulose/mannitol test values in the colostrum group fell into the normal range and dropped more than with placebo, and stool zonulin fell more too [2].

A 2009 trial gave 30 healthy men 60 g a day of colostrum, whey or nothing during 8 weeks of running [3]. The permeability ratio rose 251% with colostrum versus 21% with whey and fell 7% in controls, meaning the gut became more permeable on colostrum [3].

The 2024 meta-analysis pooled 10 trials and found a significant reduction in the lactulose/rhamnose ratio, but with heterogeneity (I² of 99%) high enough that the pooled number is fragile [1]. Gut-barrier markers such as I-FABP did not differ [1]. We grade the gut evidence C: real trials, small and inconsistent.

Immunity: fewer reported colds, little change in lab markers

A re-analysis of logbooks from earlier double-blind trials found that 32% of men taking 60 g a day of concentrated colostrum protein reported respiratory symptoms in weeks 2 to 8, versus 48% on whey; how long symptoms lasted did not differ [5]. A 2016 meta-analysis of 5 trials with 152 exercising adults estimated 44% fewer symptom days and 38% fewer episodes, but judged 4 of the 5 trials at moderate or high risk of bias [4].

When researchers measured the immune system directly, the picture was flat: across 10 trials and 239 athletes and active adults, colostrum had no or fairly low effect on serum IgA and IgG, lymphocytes, neutrophils and salivary IgA [6]. A broader 2021 systematic review called the studies highly heterogeneous [8].

Exercise and body composition

The newest trial randomized 29 club-level rugby players to 38 g a day of colostrum or soy protein for 8 weeks [7]. Vertical jump rose 1.0 cm with colostrum versus a 0.5 cm fall with soy; bench and leg-press strength, shuttle-run fitness, body composition, salivary immune and inflammation markers and reported illness did not differ [7].

Label dose versus studied dose

Studied amounts span more than a hundredfold: 0.5 g a day in the athlete gut trial, 38 g a day in rugby players and 60 g a day in the respiratory and running trials [2][7][5][3]. The colostrum capsule listed on this page provides 1,000 mg per 2-capsule serving, standardized to 30% IgG, which is in the range of the low-dose gut trial but far below the doses behind the respiratory and exercise findings [2][5][7]. A typical capsule serving cannot reproduce a 38 to 60 g powder protocol [5][7].

Colostrum is a cow's-milk product, so it is not suitable for people with cow's-milk protein allergy. For the full dose table, interactions and safety notes see the colostrum monograph; for another gut-focused supplement with stronger trials see probiotics with antibiotics.

Quick answers

Does colostrum fix leaky gut?

Trials measured permeability tests, not a diagnosis. Results were mixed: 500 mg/day improved test values in athletes, while 60 g/day worsened them in runners [2][3].

Does colostrum boost the immune system?

Exercising adults reported fewer respiratory symptom days in a 5-trial meta-analysis, but a 10-trial meta-analysis found little change in measured immune markers [4][6].

How much colostrum was used in studies?

From 0.5 g a day in a 20-day gut trial up to 38 to 60 g a day in exercise and respiratory trials [2][7][5].

Does colostrum build muscle?

In the most recent trial, 38 g/day for 8 weeks did not change strength or body composition versus soy protein in rugby players [7].

Keep reading

Full monographs

Related articles

Browse the full Supplement & Nutrient Encyclopedia or all supplement articles.

Where to buy Bovine colostrum

Products from brands we partner with that contain Bovine colostrum. Listing a product is not a claim that it works; check the amount per serving against the doses studied above, and the label for other ingredients.

  • SupersmartPaid linkColostrum2 capsules: 1,000 mg bovine colostrum standardised to 30% IgG, at the low end of the 0.5–60 g/day studied; 30 servingsShop at Supersmart (opens in new tab)Price and label checked 2026-10-11 on the brand’s site.

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References

  1. [1]Bovine Colostrum in Increased Intestinal Permeability in Healthy Athletes and Patients: A Meta-Analysis of Randomized Clinical Trials. Digestive Diseases and Sciences, 2024. PMID 38361147
  2. [2]Oral Supplementation with Bovine Colostrum Decreases Intestinal Permeability and Stool Concentrations of Zonulin in Athletes. Nutrients, 2017. PMID 28397754
  3. [3]Bovine colostrum supplementation during running training increases intestinal permeability. Nutrients, 2009. PMID 22253980
  4. [4]Bovine colostrum supplementation and upper respiratory symptoms during exercise training: a systematic review and meta-analysis of randomised controlled trials. BMC Sports Science, Medicine and Rehabilitation, 2016. PMID 27462401
  5. [5]Concentrated bovine colostrum protein supplementation reduces the incidence of self-reported symptoms of upper respiratory tract infection in adult males. European Journal of Nutrition, 2003. PMID 12923655
  6. [6]Immunological Outcomes of Bovine Colostrum Supplementation in Trained and Physically Active People: A Systematic Review and Meta-Analysis. Nutrients, 2020. PMID 32276466
  7. [7]Bovine colostrum supplementation in rugby. European Journal of Applied Physiology, 2026. PMID 40640599
  8. [8]Bovine Colostrum Applications in Sick and Healthy People: A Systematic Review. Nutrients, 2021. PMID 34202206

Bovine colostrum and other dietary supplements are not intended to diagnose, treat, cure or prevent any disease, and these statements have not been evaluated by the FDA. Talk to your clinician or pharmacist before starting a supplement, especially if you take prescription medicines. Product links on this page are paid partner links.

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