Colostrum is the fluid that new mothers' breasts produce during the first day or two after birth. It gives newborn infants a rich mixture of antibodies and growth factors that help them get a good start.

Although colostrum has been available since the first mammals walked the earth, it is relatively new as a nutritional supplement. The resurgence of breastfeeding in the 1970s sparked a revival of interest in colostrum for both infants and adults.

However, most commercial colostrum preparations come from cows, not humans. The antibodies a mother cow gives to her calf are designed to fend off bacteria that are dangerous to cows; these may be very different from those that pose risks to humans. Nonetheless, colostrum also contains substances that might offer general benefits, such as growth factors (which stimulate the growth and development of cells in the digestive tract and perhaps elsewhere) and transfer factor (which may have general immune-activating properties). In addition, some researchers have used a special form of colostrum called hyperimmune colostrum, created by inoculating cows with bacteria and viruses that affect humans. The cow in turn makes antibodies to them and secretes those antibodies into its colostrum. Hyperimmune colostrum has shown considerable promise as an infection-fighting agent.

Hyperimmune colostrum, however, is not available over-the-counter as a dietary supplement. Non-hyperimmune colostrum might have some value too, but the evidence is much weaker.

Breastfeeding is the healthiest way to nourish a newborn, and a mother's colostrum is undoubtedly good for a baby. However, do not believe claims (by at least one manufacturer) that most babies would die without colostrum. Colostrum is good for health, but it is not essential for life.

Colostrum is available in capsules that contain its immune proteins in dry form.