The colostrum benefits backed by human trials are narrower than supplement ads suggest. Bovine colostrum may reduce exercise- and painkiller-related rises in gut permeability, may cut cold-like symptoms in hard-training athletes, and may ease some infectious diarrhea[1][2][3]. Most trials are small, and a 51-study review rated the positive ones as generally poor quality[4].
Below: newborn colostrum versus adult cow colostrum supplements, the athlete gut-permeability results, the doses tested, side effects, and who should skip it.
What is bovine colostrum?
Colostrum is the first milk a mammal makes after giving birth. Bovine colostrum comes from cows, usually collected in the first days after calving, then pasteurized and dried into a powder or capsules[5]. Its concentration of immune proteins drops fast: IgG and many growth factors fall sharply by day 2 to 3 after calving[5]. Calves depend on it too: veterinary guidance calls colostrum management the single most important factor in calf health and survival[6].
Compared with ordinary cow's milk, it is far richer in antibodies and growth factors and lower in milk sugar:
| Component | Bovine colostrum | Mature cow's milk |
|---|---|---|
| Total immunoglobulins (antibodies) | 42-90 mg/mL | 0.4-0.9 mg/mL |
| IgG1 | 34-87 g/L | 0.31-0.40 g/L |
| Lactoferrin | 1.5-5 g/L | 0.02-0.75 g/L |
| Protein | 14-16% | 3.1-3.2% |
| Lactose (milk sugar) | about 2.5% | 4.7-5.0% |
Source: compiled in a 2021 review[5].
Makers use IgG content as the main quality marker: fresh colostrum with more than 50 g/L of IgG is generally considered acceptable[5]. If a label does not state IgG content, you cannot tell how much active protein a scoop holds.
Colostrum benefits for newborns vs. adults
For babies, the case is strong. The World Health Organization calls human colostrum a baby's "first vaccine" because it is rich in nutrients and antibodies[7]. Newborns who started breastfeeding 2 to 23 hours after birth had a 33% greater risk of dying than those who started within the first hour[7]. For the prebiotic side of human milk, see our page on human milk oligosaccharides (HMOs).
That evidence is about a mother's own colostrum, given to her own baby. It does not transfer to adults taking cow colostrum. Even in very preterm infants, adding bovine colostrum to feeds did not shorten the time to full feeding in a 350-infant trial[8]. Giving preterm babies small amounts of their mother's colostrum in the mouth raised secretory IgA and lactoferrin, but did not significantly reduce necrotizing enterocolitis, sepsis or death in a meta-analysis of six trials[9].
For adults, colostrum's antibodies, lactoferrin and growth factors are thought to act mainly on the gut lining[10]. In an absorption test, ingested IGF-1 showed up in the blood only as fragments, not as the intact growth factor[11].
What are the colostrum benefits for adults?
The potential benefits with the best support are narrow: gut barrier protection during heavy exercise or short NSAID courses, fewer upper respiratory symptoms in athletes, and some infectious diarrhea. Here is how each claim holds up:
| Claim | Best human evidence | Verdict |
|---|---|---|
| Tightens the gut barrier | Meta-analysis of 10 trials: lower lactulose/rhamnose ratio, but very high heterogeneity[1] | Possible, mostly in athletes |
| Fewer colds in athletes | Meta-analysis of 5 trials, 152 people: 44% fewer symptom days[2] | Possible, low-quality trials |
| Boosts immune markers | Meta-analysis of 10 trials, 239 people: no or fairly low impact[12] | Not supported |
| Treats infectious diarrhea | 22 trials: fewer bowel movements in 15 of 20 arms[3] | Some support |
| Relieves IBS | One trial of 18 patients: no benefit over placebo[13] | Not supported |
| Burns body fat | 13 trials: small, inconsistent effects[14] | Not supported |
Colostrum for gut health: what the athlete studies show
Colostrum's best-studied gut effect is on intestinal permeability, how easily molecules slip through the gut lining. A 2024 meta-analysis of 10 randomized trials found colostrum lowered the urinary lactulose/rhamnose ratio, a standard permeability test, by 0.24 on average[1]. Results varied enormously between studies (I² = 99%), and a blood marker of gut-cell damage (I-FABP) did not change[1].
Higher permeability is often marketed as leaky gut. Our leaky gut and intestinal permeability guide explains what the term does and does not mean. The results below come from specific stresses, not general gut repair.
Heavy exercise
Heavy exercise raises gut permeability[15]. In a crossover trial of 12 volunteers, permeability rose 2.5-fold after a standardized exercise test on placebo. After 14 days of colostrum, the rise was 80% smaller[15].
In 16 athletes at peak training, 500 mg a day for 20 days brought permeability tests back into the normal range. It also lowered stool zonulin, a protein linked to looser tight junctions, compared with whey placebo[16].
NSAID painkillers
NSAID painkillers such as indomethacin can injure the gut[17]. In 7 healthy men, five days of indomethacin tripled permeability when taken with whey, but caused no significant rise when taken with colostrum[17].
In 15 patients already on long-term NSAIDs, colostrum made no difference[17]. A 2021 review called the human evidence for NSAID protection "slender"[10]. Do not stop or change a prescribed NSAID based on these studies.
The trial that went the other way
Not every result points the same way. In an 8-week trial of 30 men running three times a week, 60 g a day of colostrum increased the permeability ratio by 251%. Whey raised it by 21%, and the control group changed by -7%[18]. The authors suggested colostrum may increase transport across the gut wall, as it does in newborns[18].
The microbiome angle
Colostrum is not a probiotic: it adds no live microbes. In the E. coli challenge trials, its components were thought to stop the bacteria from binding to gut cells[10].
In a Malawi trial of 267 children, colostrum plus egg did not change gut microbiota diversity compared with controls[10]. For how the gut lining and its antibody layer work together, see strengthened mucosal immunity.
Infectious diarrhea: where colostrum looks most useful
Diarrhea is the most consistent signal. A 2024 systematic review of 22 trials (1,427 patients) found colostrum reduced diarrhea frequency in 15 of 20 treatment arms, though most studies saw no change in how long it lasted[3].
- Children: in 160 Egyptian children with acute diarrhea, colostrum cut vomiting, stool frequency and severity scores within 48 hours versus placebo[19]. A 2025 review of eight pediatric studies still judged the overall benefit inconclusive[20].
- Adults with HIV-related diarrhea: in a Ugandan trial of 87 adults, colostrum reduced stool frequency and fatigue and allowed weight gain[10].
- Traveler's diarrhea: tablets made from hyperimmune colostrum, from cows vaccinated against 14 strains of Escherichia coli, gave 83-91% protection against diarrhea versus placebo after an E. coli challenge[21]. Standard store-bought colostrum is not made this way, so these results do not transfer to it. See traveler's diarrhea for proven prevention steps.
Colostrum enemas used alongside mesalazine improved symptoms in a 14-person trial in left-sided ulcerative colitis[10]. That is far too small to guide treatment, and it used rectal, not oral, colostrum.
Colostrum and immunity: fewer colds in athletes?
Colostrum may reduce upper respiratory symptoms in people who train hard, but it does not measurably boost immune function. A meta-analysis of five trials in 152 exercising adults found 44% fewer symptom days and 38% fewer episodes over 8 to 12 weeks[2]. Four of the five trials had moderate or high risk of bias, and most did not find a significant effect on their own[2].
A second meta-analysis of 10 trials found colostrum had little or no effect on blood antibodies, white blood cells or salivary IgA[12]. So if it helps, the mechanism is unclear. All five trials enrolled people in regular exercise training[2], so the result may not apply to everyone else. For everyday prevention, see our common cold page.
Is colostrum good for you, and worth the hype?
For most healthy adults, colostrum is safe but unproven. The popular claims below have little or no human support:
- Skin, hair and anti-aging: we found no controlled human trials of oral colostrum for skin or hair.
- Weight and belly fat: a 2026 review of 13 trials found only small, inconsistent changes, such as a 0.4% drop in body fat in one study[14].
- IBS: in the only randomized trial we found, 18 patients with IBS took 15 mL daily for 4 weeks. Symptom relief was 55.5% with colostrum versus 44.4% with placebo, a difference that was not significant[13].
- General immunity: immune markers barely move in trials[12].
The 2014 review of 51 studies put it plainly: studies suggesting clinical benefit were generally of poor quality and could not be confirmed by other investigators[4].
Colostrum side effects and who should avoid it
A 2021 review describes colostrum as having a strong safety profile[5], but some groups should skip it:
- Cow's milk allergy: colostrum contains beta-lactoglobulin, a major allergen for people with milk allergy[5].
- Lactose sensitivity: colostrum still has about 2.5% lactose unless the maker removes it during processing[5]. See lactose intolerance if milk sugar bothers you.
- Drug-tested athletes: colostrum contains small amounts of IGF-1, a growth factor on the World Anti-Doping Agency's Prohibited List[22]. The NCAA lists IGF-1, naming colostrum as a source, among its banned substances[23], and the US Anti-Doping Agency warns colostrum "could be risky for athletes"[24].
- Pregnancy, breastfeeding and weakened immunity: none of the trials we reviewed tested these groups, so check with your clinician first.
IGF-1 and cancer worries. Because IGF-1 is a growth factor, some worry colostrum could raise blood levels. A single 40 g dose and 20 g a day for 4 or 12 weeks did not raise plasma IGF-1 in healthy adults[25]. Neither did 60 g a day for 4 weeks[26]. One 2002 trial of 20 g a day did report an increase[11], so the question is not fully closed.
Quality is unregulated. The FDA does not approve dietary supplements before they are sold[27]. Look for third-party testing and a stated IgG content.
How much colostrum do studies use?
There is no established dose. Trials have used anything from 500 mg[16] to 60 g a day[18], and the most-cited results came from very different amounts. These are the amounts studies used, not recommendations:
| Study population | Amount studied | Duration | Result |
|---|---|---|---|
| 16 athletes in peak training | 500 mg/day | 20 days | Lower permeability vs. placebo[16] |
| 7 healthy men taking indomethacin | 125 mL three times daily | 5 days | Blocked NSAID permeability rise[17] |
| 18 people with IBS | 15 mL/day | 4 weeks | No benefit vs. placebo[13] |
| Healthy adults (safety) | 20 g/day | 4 and 12 weeks | No rise in IGF-1[25] |
| 30 men in running training | 60 g/day | 8 weeks | Permeability rose[18] |
| 90 volunteers challenged with E. coli | 400 mg hyperimmune protein, three times daily | Challenge period | 58-91% protection[21] |
The table shows why "how much should I take?" has no clean answer. A low dose helped in one small trial[16], while a high dose made permeability worse in another[18].
The bottom line
Colostrum is essential for newborns. For adults, the evidence supports, at most, short-term use in specific situations: hard training, a short NSAID course or some infectious diarrhea. Even there, trials are small and results conflict[1][18]. For day-to-day gut support, food is a better starting point: see our gut-healthy diet guide.
This article is for general educational purposes and is not medical advice. Bovine colostrum is a dietary supplement that is not approved by the FDA to diagnose, treat or prevent any disease, and it does not replace care for diarrhea, inflammatory bowel disease or other diagnosed conditions. Talk to a qualified healthcare professional before taking colostrum, particularly if you are pregnant, immunocompromised, have a milk allergy, compete in drug-tested sport, take prescription medication, or manage a diagnosed condition.
Frequently Asked Questions
Is colostrum FDA approved?
No. Colostrum is sold in the US as a dietary supplement, and the FDA does not have the authority to approve dietary supplements for safety or effectiveness before they are marketed. Its role is mostly enforcement after products reach shelves, and companies generally do not have to show the FDA their safety evidence first. That means dose, IgG content and purity can differ between brands, so third-party testing on the label matters more than marketing claims.
Why is colostrum banned by the NCAA?
Because of IGF-1. The NCAA's banned-substances list names IGF-1 under peptide hormones and growth factors, with colostrum and deer antler velvet given as example sources. IGF-1 is also on the World Anti-Doping Agency's Prohibited List, and the US Anti-Doping Agency warns there is no guarantee oral colostrum will not trigger a positive test. Trials giving 20 to 60 g a day mostly found no rise in blood IGF-1, but one 2002 trial did, so tested athletes should avoid it unless their governing body says otherwise.
Can colostrum fix leaky gut?
No supplement has been shown to fix it. In randomized trials, colostrum lowered lab measures of intestinal permeability on average, mostly in athletes during heavy training or in people taking a short NSAID course, but results varied widely and one 8-week running trial found permeability rose. Persistent gut symptoms need a medical workup rather than a supplement. Our leaky gut guide explains what the term does and does not mean.
Does colostrum fix IBS?
There is no good evidence that it does. The only randomized trial we found gave 18 people with IBS 15 mL of colostrum or placebo daily for 4 weeks: symptom relief was 55.5% versus 44.4%, a difference that was not statistically significant, and the authors concluded colostrum had no benefit for symptoms. Diet changes and treatments with stronger evidence are covered on our IBS page.
Does colostrum burn belly fat?
There is no good evidence that it does. A 2026 systematic review of 13 clinical trials found only small, inconsistent effects: one study in older adults taking 60 g a day for 8 weeks saw body fat percentage fall by 0.4%, and another found less leg fat gain when colostrum was combined with plant protein. The reviewers called for larger trials lasting at least six months before any conclusion can be drawn.
Is taking colostrum unethical?
It depends on how a supplier sources it, which most labels do not explain. Newborn calves rely on colostrum: veterinary reviews call colostrum management the single most important factor in calf health and survival, and calves need enough clean, high-quality colostrum within the first few hours of life. If this matters to you, ask the brand how it ensures calves are fed first, and look for a written answer rather than a slogan.
What happens if I take colostrum every day?
In trials, healthy adults have taken 20 g a day for up to 12 weeks without a rise in blood IGF-1, and reviews describe colostrum as generally well tolerated. Daily use has not been shown to make healthy people's guts or immune systems measurably better, though. The most consistent signals come from athletes in heavy training and from people with infectious diarrhea, so for most adults daily use mainly adds cost.
Are there specific colostrum benefits for women or for men?
No sex-specific benefits have been shown. The trials that drive most claims were small and often enrolled only men, such as the NSAID permeability study (7 men) and the 8-week running trial (30 men). Marketing aimed at women usually leans on skin, hair or weight claims that lack human trial support, so judge any product by the same evidence summarized above.
When is the best time to take colostrum?
No trial has compared morning and evening dosing or taking it with or without food, so there is no evidence-based best time. Studies dosed it in different ways: three times daily alongside a drug in an NSAID trial, once daily before breakfast in an IBS trial, and daily for 14 days before a heavy exercise test in athletes. If you take it, follow the label and take it consistently.
Does colostrum have a laxative effect in adults?
Not in the trials we reviewed. In clinical studies of people with diarrhea, colostrum tended to reduce stool frequency rather than increase it: a 2024 systematic review found lower stool frequency in all seven studies that measured it. People who are sensitive to milk sugar may still notice symptoms, because colostrum contains about 2.5% lactose unless the maker removes it.
References
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