The short version
- In 30 men running three times a week for eight weeks, 60 g a day of bovine colostrum increased the urinary lactulose to rhamnose ratio by 251% against 21% on whey protein and −7% on control.
- In an eight-person crossover trial, exercise tripled gut permeability and fourteen days of bovine colostrum or zinc carnosine each cut that rise by about 70%.
- The two results differ in dose, duration and what they measured: one tracked chronic resting permeability at 60 g a day, the other blunting of an acute heat and exercise challenge.
- A 2022 systematic review found nine eligible studies and called for well-designed randomised trials to establish long-term safety and optimal dosing.
- Every human gut-barrier trial of colostrum has been run in exercising people, so there is no trial evidence for its use in a sedentary adult with general digestive complaints.
Colostrum is the first milk a cow produces after calving, and it is genuinely unusual stuff: concentrated immunoglobulins, growth factors including IGF-1 and TGF-beta, lactoferrin and oligosaccharides. Its job in a newborn calf is to get antibodies across the gut wall and into circulation during the brief window when that is possible.
Hold onto that last clause. It explains the strangest result in this literature.
Two trials, both randomised, both controlled, pointing opposite ways
Buckley and colleagues gave 30 healthy adult men 60 g a day of bovine colostrum, whey protein, or a control, while they ran three times a week for 45 minutes at their lactate threshold for eight weeks. They measured the urinary lactulose to rhamnose ratio before and after.
Permeability went up in the colostrum group — by 251 ± 140%, against 21 ± 35% on whey protein and −7 ± 13% on control. The authors' own explanation is the interesting part: colostrum may have induced greater leakiness of the tight junctions, or it may have increased macromolecular transport the way it does in the neonatal gut. In other words, it may have been doing precisely what colostrum evolved to do.
Davison and colleagues ran a four-arm double-blind placebo-controlled crossover in eight volunteers: fourteen days each of placebo, zinc carnosine, colostrum, or both, with standardised exercise afterwards. Body temperature rose 2°C and gut permeability tripled after exercise, from a lactulose:rhamnose ratio of 0.32 at baseline to 1.0 at fourteen days. Zinc carnosine or colostrum each truncated that rise by 70%, and the combination added a further benefit at day two.
So one trial says colostrum raised permeability by two and a half times. The other says it cut the exercise-induced rise by 70%. Neither is fraudulent, and both are small.
How to hold both at once
The differences are not subtle. Buckley used 60 g a day for eight weeks and measured chronic change in resting permeability. Davison used a lower dose for fourteen days and measured the acute response to a heat and exercise challenge. One asks what colostrum does to a baseline; the other asks whether it blunts an insult.
And there is the deeper point. We tend to assume more permeability is bad and less is good. In a newborn gut, high macromolecular transport is the feature, not the fault — it is how maternal antibodies get in. If bovine colostrum partially reopens that route in an adult, "permeability increased" may be a description of the mechanism working rather than of harm. Nobody has established which it is. That is not us hedging; it is the state of the field.
A 2022 systematic review found nine eligible studies and concluded that vigorous exercise profoundly increases permeability and that colostrum helps reverse it — while calling for well-designed, placebo-controlled randomised studies to evaluate long-term safety and to determine the optimal dose. Nine studies and a request for proper dosing work is an honest summary of a small field, not a mature one.
Who this is actually for
Every trial above is in athletes, because exercise is the reliable way to provoke a measurable permeability change in healthy people. If you are training hard, in heat, and getting gut symptoms during long sessions, you are the population that has actually been studied, and a fourteen-day trial before your next hard block is a reasonable experiment.
If you are not, be clear that you are extrapolating. There is no trial showing colostrum improves digestion, reduces bloating or repairs a gut in a sedentary adult with vague symptoms, and the wider leaky gut framing that gets attached to it is doing more work than the evidence permits — restoring intestinal permeability has never been shown to fix a clinical problem in the first place.
Practical points we would want you to know
- It is dairy. Colostrum contains milk proteins, so it is out for anyone with a milk allergy and not vegan. It is low in lactose but not lactose-free.
- Doses in these trials ranged from a few grams to 60 g a day. Most retail products, ours included, sit far below the Buckley dose, so do not read that trial as describing your capsule.
- IgG content is the number worth looking for on a label, and plenty of products do not state it.
- Give it two weeks against one specific thing you can notice, not a general feeling.
One more honest note. If you are taking colostrum because you have just finished antibiotics and want to rebuild, the evidence for probiotics after antibiotics is more complicated than the category admits, and the colostrum evidence for that use does not exist at all.
We sell colostrum in capsule and powder form. It supports the gut barrier in the specific, exercise-stressed context above; that is a structure and function statement and it is as far as the data goes. It does not treat, cure or prevent anything, and if your symptoms have been going on for months the appointment is worth more than the tub.
Good questions
Does colostrum help leaky gut?
It measurably changes gut permeability in exercising people, in both directions depending on the trial. Sixty grams a day for eight weeks raised it by 251% in runners; fourteen days of a smaller dose cut the exercise-induced rise by 70%. It has never been shown to fix a clinical problem by restoring the barrier, because no supplement has.
How much colostrum should I take?
Nobody knows the optimal dose, and the 2022 systematic review says so explicitly. Trials have ranged from a few grams to 60 g a day, and the extremes produced opposite permeability results. Most retail products sit near the low end. Start at the label dose, give it two weeks, and judge it against one thing you can actually notice.
Is colostrum worth it if I do not exercise hard?
Probably not, on current evidence. Every human gut-barrier trial has used exercise as the challenge, because that is the reliable way to move the measurement. There is no trial showing colostrum improves digestion or reduces bloating in a sedentary adult. Buying it for general gut health is extrapolating from athletes to yourself, and we would rather you knew that.
Can I take colostrum if I am lactose intolerant?
Cautiously. Colostrum is low in lactose but it is a dairy product and contains milk proteins, so it is unsuitable for anyone with a milk allergy and not vegan. If lactose is your problem, the amount in a capsule is likely to be small, but the honest answer is to try a low dose and see rather than to assume.
Does colostrum survive stomach acid?
Partially, and this is a genuine open question rather than a settled one. Immunoglobulins are proteins and proteins get digested, which is why some products use enteric coating. The trials above measured outcomes rather than survival, so they tell you something happened without telling you how much protein made it through intact.
Is increased gut permeability from colostrum a bad thing?
It might not be. In a newborn gut, high macromolecular transport is the point, since it lets maternal antibodies cross. If bovine colostrum partially reopens that route in adults, a rise in the permeability measurement could describe the mechanism working rather than harm. Nobody has established which, and any brand claiming certainty here is inventing it.
Sources
- Buckley JD, Butler RN, Southcott E, Brinkworth GD. Bovine colostrum supplementation during running training increases intestinal permeability. Nutrients, 2009. View study
- Davison G, Marchbank T, March DS, Thatcher R, Playford RJ. Zinc carnosine works with bovine colostrum in truncating heavy exercise-induced increase in gut permeability in healthy volunteers. Am J Clin Nutr, 2016. View study
- Dziewiecka H, Buttar HS, Kasperska A, et al. A Systematic Review of the Influence of Bovine Colostrum Supplementation on Leaky Gut Syndrome in Athletes: Diagnostic Biomarkers and Future Directions. Nutrients, 2022. View study
- Camilleri M. Leaky gut: mechanisms, measurement and clinical implications in humans. Gut, 2019. View study
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
