Colostrum

Intestinal permeability and digestive health

The indication with the strongest clinical support is improving the integrity of the intestinal barrier in situations of hyperpermeability: several small trials have documented improvements in markers of intestinal permeability and in digestive symptoms with supplementation at 10–60 grams daily for weeks to months, an indication consistent with the intestinal epithelial growth factors and immunomodulatory components present in colostrum.

In "athlete's gut" (the intestinal hyperpermeability associated with extreme endurance exercise in conditions of heat and dehydration), several studies have shown significant reductions in markers of permeability and endotoxemia with specific supplementation before and during long-duration events, an indication with moderate clinical support in endurance sports medicine.

Infectious diarrhea and gastrointestinal conditions

In infectious diarrhea (especially rotavirus in pediatrics and Cryptosporidium diarrhea in immunocompromised patients), several trials have documented reductions in duration and severity with specific supplementation with hyperimmune colostrum (colostrum from cows previously immunized against the specific pathogen); non-hyperimmune commercial preparations have more modest but also documented effects in nonspecific diarrhea.

Immunity and prevention of respiratory infections

In people prone to recurrent respiratory infections, especially athletes during periods of high training load, several small studies have documented modest reductions in the frequency and severity of respiratory infections with supplementation over weeks to months, an indication with moderate clinical support that is consistent with its immunomodulatory profile.

How to take it and precautions

The doses studied vary enormously depending on the indication: for gut health and athletes, 10–20 g/day divided; for general immunity, 5–10 g/day; for infectious diarrhea, specific doses according to clinical protocols; typical commercial products are a soluble powder that dissolves in water or milk, with a characteristic slightly milky taste; good-quality products state their immunoglobulin content (ideally at least 20–30 percent bovine IgG) and the processing method.

The most important safety consideration is the quality and origin of the product: low-quality or improperly processed colostrum may contain microbial contaminants, residues of veterinary drugs, or adulteration with conventional milk proteins (which have a much less biologically active profile); people with a cow's milk protein allergy should avoid colostrum completely; those with lactose intolerance should prefer low-lactose products or use small doses with care; products without adequate processing may contain IGF-1 and other growth factors in amounts that some specialists have suggested are theoretically concerning in people with IGF-1-dependent cancers, although human clinical data show no clear signals of increased risk with supplementation at usual doses; in pregnancy and breastfeeding, specific data are limited and avoidance is recommended as a precaution; cheap products may have a real immunoglobulin content much lower than declared, and it is advisable to choose products from manufacturers with a good reputation for quality control and independent verification of bovine IgG content.

What the latest science says

Bovine colostrum has gone from a niche supplement to one of the most studied for immunity and gut health. The strongest evidence is for preventing respiratory infections in people who train hard: a meta-analysis of five trials found 44 percent fewer days with symptoms and 38 percent fewer episodes with 10–20 grams a day for 8–12 weeks, with a somewhat larger effect at 20 grams [6].

In children, another meta-analysis of five trials showed that colostrum, especially the hyperimmune kind, reduces infectious diarrhea and the presence of rotavirus and E. coli in stool [7], and a 2023 trial in children aged 3 to 7 found half as many respiratory infection episodes over autumn and winter with very small doses, from half a gram to one gram a day [8].

In adults aged 50 to 85, a 2026 trial with 188 people did not change its main outcome, salivary IgA, but recorded fewer colds, mouth ulcers and less fatigue than with regular milk powder; the authors consider it an exploratory result that needs confirming [9].

How it would work: a barrier rather than a stimulant

When antibodies and immune cells are measured in blood, colostrum barely moves them: a meta-analysis of ten trials in athletes found no changes in blood IgA or IgG, salivary IgA, lymphocytes or neutrophils [10]. A 2024 crossover trial with 25 grams a day for 12 weeks did see salivary IgA rise right after exercise [11]. The most accepted hypothesis is that it acts mainly on the mucosa, where its immunoglobulins, lactoferrin and growth factors reinforce the barrier of the gut and airways, rather than stimulating the immune system in general.

The same idea fits the gut results: 20 grams a day for two weeks almost cancelled the rise in gut permeability caused by running in the heat [3], 500 milligrams a day reduced stool zonulin in athletes [1], and in healthy volunteers colostrum prevented the anti-inflammatory indomethacin from tripling gut permeability [12]. Not every study replicates this, and the quality and bioactivity of the product seem to matter a lot [13].

Where there is no clear benefit

For losing fat or improving cholesterol, a 2026 systematic review of 13 trials concludes that certainty is very low: some studies show lower cholesterol or triglycerides, but most do not differ from placebo [14]. In preterm infants, a 2026 meta-analysis of 670 babies found no effect on necrotizing enterocolitis or on time to full feeding, and its authors do not recommend it in this group [15]. For sports performance the results are mixed: some trials show better performance in cyclists and faster recovery during intense training blocks, and others do not [13].

Men and women

Almost all the evidence in adults comes from male athletes: around 80 percent of participants in the sports meta-analyses were men [6][10], and the 2024 trial included only men [11]. The trials in children and older adults include both sexes but do not analyze the differences separately, so it is not yet known whether the effect is the same in women.

Dose, quality and anti-doping

The best-supported doses are 10–20 grams a day in adults and half a gram to one gram in young children, starting 2 to 8 weeks before the highest-risk season. Although colostrum contains IGF-1, studies with a protein-matched placebo show no rise in blood IGF-1 and no interference with anti-doping tests, and it is not banned in sport [13].