What does it do? Bovine colostrum is the pre-milk liquid produced from the mammary glands of cows during the first 24 to 48 hours after giving birth. Bovine colostrum is rich in immunoglobulins (antibodies), growth factors, various proteins, and enzymes. The question regarding bovine colostrum is whether these factors, which are meant for the calf, exert any effects in humans.

Bovine colostrum may turn out to be an important nutritional supplement, but for now there are no conclusive data to support manufacturers’ claims. Although various components of bovine colostrum theoretically may produce some benefits, there are no studies where bovine colostrum—in the forms that are commercially available—has been given to humans and shown benefits.

It has been claimed that bovine colostrum can help fight certain infections. However, the research studies used to support that claim used colostrum derived from cows immunized in a way that caused them to produce unusually large amounts of a specific antibody in their colostrum. For example, in a double-blind study, children with diarrhea caused by a rotavirus were treated with immunoglobulins extracted from colostrum, derived from cows immunized with rotavirus. Compared with the placebo, administration of the immunoglobulins significantly reduced the amount of diarrhea and the amount of oral rehydration solution required. In addition, the rotavirus was eliminated from the stool significantly more rapidly in the immunoglobulin group than in the placebo group (1.5 days vs. 2.9 days).¹

In addition to a positive effect against acute rotavirus diarrhea,^{2 3} there is also evidence that specific forms of colostrum (derived from specially immunized cows or those with confirmed presence of specific antibodies) are effective against diarrhea caused by Cryptosporidium parvum, Helicobacter pylori, Escherichia coli, and Clostridium difficile.^{4 5 6 7 8} However, it is not known whether commercially available colostrum provides significant amounts of the specific immunoglobulins that are active against these organisms. Furthermore, unless the immunoglobulins are present in high enough concentrations, the preparation is not likely to be effective. There is evidence that the majority of the antimicrobial effect of both bovine colostrum and one of its chief antibiotic components (lactoferrin) are destroyed by gastric secretions and by the digestive enzyme, trypsin.⁹

Bovine colostrum contains bovine versions of many human growth factors, including insulin-like growth factor, transforming growth factor, epithelial growth factor, and even growth hormone, that are capable of stimulating muscle growth. The concentration of bovine insulin-like growth factor I (ILGF-I) in colostrum ranges from 200 to 2,000 mcg/L, compared with less than 10 mcg/L in normal cow’s milk.¹⁰ Thus, in theory, bovine colostrum might be able to stimulate muscle growth in humans. However, although bovine ILGF-I has been shown to be identical to human ILGF-I in some analytical studies¹¹ and to be absorbed and transported into the circulation in calves,¹² the effects of bovine ILGF-I and other bovine growth substances in humans after oral administration, has not been determined in clinical trials.

In a preliminary study of male athletes, supplementation with 125 ml of colostrum per day for eight days produced a statistically significant increase in the serum concentration of insulin-like growth factor.¹³ However, the magnitude of the increase was small, and the clinical significance of that change is not clear. Thus, claims that bovine colostrum can help burn fat and promote muscle growth by raising the level of ILGF-I or other molecules must be considered premature.

Bovine colostrum may be helpful in protecting against peptic ulcer formation caused by non-steroidal anti-inflammatory drugs like aspirin, ibuprofen, and indomethacin. In a study in rats, pretreatment with 0.5 or 1.0 ml of a colostrum preparation reduced indomethacin-induced gastric injury by 30% and 60%, respectively.¹⁴ Whether bovine colostrum exerts this effect in humans has not been determined.

Claims that bovine colostrum elevates mood, that “colostrum is a natural and healthy means of stimulating the brain to release serotonin and dopamine and prolong their re-uptake,” or that “colostrum also activates the release of other chemicals in the brain that affect alertness and concentration” are unsubstantiated.