Colostrum is the clear or cloudy "premilk" female mammals secrete after giving birth and before producing milk. Colostrum for dietary supplements is usually derived from bovine sources and contains various immunoglobulins (also called antibodies) and antimicrobial factors (i.e., lactoferrin, lactoperoxidase, lysozyme) as well as insulin-like growth factors such as IGF-I and IGF-M. The concentration of IGF-I in bovine colostrum is 200-2,000 mg/L, whereas normal milk contains less than 10 mg/L. In normal, healthy adults, IGF-1 occurs at a concentration of approximately 200 mg/L in serum. In terms of immunoglobulins, colostrum generally provides concentrations of IGF, IgM, and IgA that are 100-fold higher than in normal milk. The most prevalent claims for dietary supplements containing colostrum are in the area of generalized immune function as well as the specific areas of diarrhea prevention and treatment, overall gastrointestinal support, and improved recovery from intense exercise.
The amino acid sequences of human and bovine IGF-I are identical. The increase in serum ICF-I observed in several human studies is most likely a result of an enhanced stimulation of endogenous IGF-I synthesis rather than a direct absorption of the growth factor from the adult gastrointestinal tract. It is likely that the natural target of colostrum-derived growth factors is the gastrointestinal tract, whereby the increased growth and turnover of the intestine provides for a healthier gut and an increased uptake of dietary components that may enhance growth, immune competence, and athletic performance generally.
Bovine colostrum contains the same disease-resistance factors (immunoglobins) found in human breast milk and unpasteurized cow's milk. Among the many immune factors that may be effective against various viruses, bacteria, yeast, and other invaders are immunoglobins (IgA, JgG, IgM) lactoferrin, laclalbum'm, glycoprote'ins, cytokines (such as interleukin 1, interleukin 6, and interferon Y) and various polypeptides, growth factors, vitamins, and minerals. The antibodies present in colostrum are thought to combine with disease-causing microorganisms in the gastrointestinal tract. By adhering to pathogens, colostrum antibodies may be able to reduce the adhesive properties of bacteria and decrease their ability to attach to the intestinal wall (which could prevent their entrance into the body). Ii is unlikely that the "full" antimicrobial benefits of colostrum can be realized unless the user happens to be a baby cow, because the immunoglobulins are largely digested in the adult gut and cannot be absorbed intact (Mero et al,, 2002). It may be possible, however, for partially digested immunoglobulin fragments to retain a small portion of their functional properties and deliver these immune benefits on absorption.
Numerous studies have been conducted in adults and children to show the benefits of ingesting colostrum in neutralizing the activity of several strains of bacteria and parasites that cause diarrhea (Ashraf et al., 2001; Bolke et al., 2002; Huppertz et al., 1999; Mitra et al., 1995; Nord et al., 1990; Okhuysen et al., 1998; Plettenberg et al., 1993; Rump etal., 1992; Sarkeretal., 2001; Tacketetal., 1988; Tawfeek et al., 2003). Both the prophylactic and treatment effects of colostrum feeding against bacterial and parasitic infections of the gastrointestinal tract may be the result of the direct antimicrobial effects of colostrum-derived immune factors and/or a generalized stabilization of gut barrier function (Bolke et al., 2002; Playford et al., 2001). In studies of chronic gastritis, symptoms were improved and inflammation was reduced, but there was no evidence that colostrum was directly effective against Helicobacter pylori (the bacteria that cause stomach ulcers).
In terms of sports performance, several studies have investigated athletes who consumed colostrum (up to 60 g/day) compared with a placebo or whey protein. These studies found variable effects on IGF-I levels. In terms of overall athletic performance and exercise recover)', they found no differences in plasma IGF-1 concentrations in either group during the study period but they did find that the colostrum group ran further and did more work than the placebo group (equal to a 2% increase in performance; Antonio et al., 2001; Brinkworth et al., 2002; Buckley et al., 2002, 2003; Coombes et al., 2002; Hofman et al., 2002). One study examined rowing performance in a group of elite female rowers. Eight rowers completed a 9-week training program while consuming either colostrum (60 g/day) or whey protein. By week 9, rowers consuming colostrum had greater increases in the distance covered and work done compared to the whey protein group (Brinkworth ct al., 2002).
Additional studies on bovine colostrum consumption suggest that it can also deliver some generalized anti-inflammatory benefits (Bolke et al., 2002; Playford et al., 2001) and help prevent and treat the gastric injury associated with non-steroidal anti-inflammatory drugs. Such effects may also be of value for the treatment of ulcerative conditions of the bowel, such as colitis and irritable bowel syndrome (Khan et al., 2002).
Taken together, the available evidence for bovine colostrum is supportive of its benefits as an effective immune-supporting supplement, particularly when interactions with pathogens in the intestinal tract are possible. It is unlikely; however, that colostrum would provide immune benefits against airborne pathogens and upper respiratory tract infections such as cold and influenza or against pollen-related allergic responses (Leifer-man et al., 1975).
No adverse side effects are expected up to doses of 60 g/day, but people with milk allergies should avoid bovine colostrum. Doses of 10 g and up have been used in most human studies; it is unknown if lower doses provide any meaningful immune or gastrointestinal benefits. Many capsule-form products provide no more than 1 g of colostrum per serving, but powder forms may deliver levels associated with clinical effectiveness (10 g and higher).