Humans and all other lactating mammals produce colostrum, the first secretion from a mother's breasts after the birth of a baby. Colostrum is a rich source of proteins and antibodies that confer temporary resistance to disease until the infant's own immune system begins to function.
Bovine colostrum is collected from cows in the first milking after their calves are born. Ayurvedic physicians in India have been recommending bovine colostrum for thousands of years and, reportedly, Scandinavian farmers use it to make desserts to celebrate good health and the birth of healthy calves.
Bovine colostrum has been sold for many years as a supplement in pill form and as powders, bars and liquids, but I'm skeptical of the many extravagant health claims made for it: that it burns fat, builds muscle, speeds healing of injuries, regulates blood sugar, boosts mood, treats everything from depression to gingivitis, and cures the flu, as well. The supposed science behind these inducements to buy the stuff is that after puberty, the human body produces less of the immune and growth factors needed to combat disease and heal damaged tissue. That may be true, but there is no evidence to support the claim that taking supplemental colostrum can restore youthful levels of these substances and cure whatever ails you.
I've seen no good research on the effects of bovine colostrum in humans and no data to support the many claims made for it. A few small-scale animal studies suggest that bovine colostrum has antimicrobial activity, but they were not well designed. Bottom line: we need more and better studies before we can be sure of either the safety or efficacy of bovine colostrum supplements. Save your money.
Andrew Weil, M.D.