Quick answer

Bovine colostrum is the first milk a cow makes after calving, dried to a powder. Its one graded benefit is early: in two small trials, 1 g a day for 20 days lowered a gut permeability test in athletes. Most trials used 10 to 20 g a day, and low doses did not change immune measures.^1,2,3,4,5

Key facts

Fresh colostrum carries about 42 to 90 mg of immunoglobulins per mL, against 0.4 to 0.9 mg in mature cow's milk.¹
Cow antibodies are unlikely to reach the human bloodstream intact, so any effect is thought to happen in the gut.¹
Colostrum collected 72 hours after calving did not change the gut test, while colostrum from 2 or 24 hours did.³
WADA does not ban colostrum but advises athletes against it because of its growth factors.⁴

What colostrum is

Colostrum is the milk made in the first few days after birth. Bovine colostrum comes from cows, and the dairy industry collects and dries it for supplements.¹

IgG is the main antibody in bovine colostrum, at about 30 to 87 g per liter, and makes up about 80 to 90% of its immunoglobulins.¹

Fresh colostrum is about 14 to 16% protein, 6 to 7% fat and 2 to 3% lactose, against about 3% protein, 4% fat and 5% lactose in mature milk.¹

This page is about cow colostrum sold as a supplement. It is not about the first milk a newborn baby drinks, which is a different subject.

How it is thought to work

Reviewers consider it unlikely that cow IgG is absorbed intact into the human bloodstream, so any effect is thought to happen in the gut.¹

In seven healthy adults who drank a cow immunoglobulin concentrate after an overnight fast, about 19% of the IgG reached the end of the small intestine still active. Other milk proteins are more than 90% digested by that point.⁶

Hard exercise, especially in the heat, makes the gut lining more permeable for a while. That is why most colostrum research in healthy people measures gut permeability, using sugar drinks and a urine test rather than anything people feel.^4,7

What the evidence shows

One claim passes our evidence rules. It is graded early because it rests on two small trials from one research group, and the amount those trials used is shown with it.^2,3

Helps maintain normal gut barrier function in athletes during hard training*^2,3,4,7

Early evidence

Two small placebo-controlled trials from one research group, in 16 and 31 athletes, found that 1 g a day of freeze-dried colostrum for 20 days lowered a urine-test measure of gut permeability. A 2024 meta-analysis of 10 trials also found lower permeability markers, with very inconsistent results between trials, and most colostrum trials used 10 to 20 g a day. The 1 g trials used colostrum collected within 24 hours of calving. This label does not state collection time or processing, so the match is uncertain.

Amount studied: 1 g a day (500 mg twice a day) for 20 days in the two small trials; most other trials used 10 to 20 g a day

In 12 volunteers, a hard 20-minute run raised a urine test of gut permeability 2.5-fold after 14 days of placebo. After 14 days of colostrum at 20 g a day, the rise was 80% smaller.^4,8

Not every trial agrees. Some studies of exercise in the heat found no effect on a blood marker of gut cell damage, and a 2024 pooled analysis found results that varied widely between trials.^4,7

What has not been shown

In 138 healthy adults aged 40 to 80, 1.2 g a day for 10 weeks did not change any immune measure tested, including responses to two vaccines.⁵

Pooling 10 trials in 239 athletes and active adults, colostrum had little or no effect on antibody and white cell levels in blood or on antibody in saliva.⁹

A 2021 review rates the evidence on body composition and performance as limited, partly because many trials used a placebo that was not matched for protein and energy.⁴

Trials in athletes that counted days of illness used 10 or 20 g a day, and most had design problems that could bias their results. This site makes no claims about illness.¹⁰

How much was used

Most human trials of colostrum used 10 to 20 g a day.⁴

Two small trials in athletes gave 1 g a day, as 500 mg twice a day, for 20 days.^2,3

The dosage guide lists each amount tested, from 1 g to 60 g a day, with what each trial measured.^2,11

Why one powder differs from another

Colostrum is generally counted as colostrum only up to day 3 after calving, and IgG falls fast on days 2 and 3. Some producers sell late colostrum collected on days 5 to 7.¹

Commercial colostrum products have differed up to six-fold in laboratory tests of activity, which reviewers link to collection time, storage, processing and pasteurization.¹

Many makers do not say when their colostrum was collected. That matters, because the low-dose trials that found a change used freeze-dried colostrum collected within a day of calving.³

What's in ours

What’s in ours

Colostrum: Bovine Colostrum (25% Immunoglobulin G), 2,300 mg per serving, from the label

Our label lists the colostrum and its IgG content, shown above. It does not say when the colostrum was collected or how it was dried, so it cannot be matched exactly to the low-dose trials.

Side effects, allergy and who should ask first

Mild stomach problems were reported in one trial, in women only, and generally faded with time. The other trials in the same review reported no side effects or did not say.¹⁰

In a 107-day trial at 0.5 to 1 g a day, digestive symptoms were no more common than with placebo, and no serious adverse events were reported.¹²

No upper limit has been set for colostrum. Most trials used 10 to 20 g a day for up to 12 weeks, and a few used 60 g a day for 8 to 9 weeks. Reviewers describe it as generally well tolerated while noting that side effects were poorly reported.^4,10,11,13

WADA does not prohibit colostrum, but since 2013 it has advised athletes against it because its growth factors could affect a doping test.⁴

Do not take colostrum if you have a milk allergy. It is a milk product and keeps the proteins of cow's milk.¹
Ask first if you are lactose intolerant, pregnant or nursing, or under 18.
Ask first if you compete in a drug-tested sport.⁴
Ask your doctor or pharmacist if you take prescription medicines.

No official source we use lists a medicine that interacts with colostrum, and the trials did not look for interactions. That gap is not proof of safety.

Questions people ask

What does colostrum do for adults?

In healthy adults, the clearest finding is a smaller rise in gut permeability around hard exercise, seen at 1 g a day in two small trials and at 20 g a day in a crossover trial. Results on immune measures and strength have been mixed or limited.^2,4,5,8

Is there colostrum in milk or other foods?

Not in useful amounts. Colostrum is made only in the first few days after calving, and mature cow's milk carries roughly a hundredth of its immunoglobulin content.¹

Does colostrum raise IGF-1 or affect a drug test?

Most studies found no rise in blood IGF-1, over hours or over weeks. WADA still advises athletes against colostrum, so check with your sport's governing body if you are tested.⁴

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Sources

*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.

This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.