Colostrum is the first form of milk produced by the mammary glands of mammals (including humans) immediately following the delivery of the newborn. In general, protein concentration in colostrum is substantially higher than in milk as it contains more lactalbumin and lactoprotein and is also rich in antibodies that confer passive immunity to the newborn.

Colostrum is an important natural substance to help athletes achieve their desired results. Research shows that colostrum can help to increase strength and endurance, build lean muscle mass, burn body fat, which typically dips after strenuous exercise, shorten recovery time and accelerate healing of injuries. Colostrum contains not only main growth factors such as EGF, BTC, IGF-Ⅰ, IGF-Ⅱ, TGF-β1, TGF-β2, FGF1 and 2, and PDGF but also components capable of promoting bone formation and inhibiting bone resorption. (1, 2) According to a study conducted in Finland, IGF-1 induces protein synthesis, which leads to an increase in lean muscle mass without a corresponding rise in adipose fat tissue. The IGFs in humans and cows are identical, but bovine colostrum actually contains a greater concentration of IGF-Ⅰ than human colostrum. The most abundant growth factors in colostrum are IGF-Ⅰ, IGF-Ⅱ which stimulate cell growth and are proposed to act both as endocrine hormones via the blood and as paracrine and autocrine growth factors locally. IGF-Ⅰ which is the most abundant growth factors in colostrum can mimic most effects of growth hormone and mediate growth hormone effects on skeletal muscle. (3, 4) Another growth factor of colostrum, platelet-derived growth factor (PDGF) helps to stimulate the production of other growth factors, including IGF-1. Other growth factors in colostrum include growth hormone (GH) shown to accelerate bone regeneration, TGF α and TGF β shown to regulate cellular migration, proliferation and fibroblast growth factor (FGF) shown to be a powerful stimulator of angiogenesis and a regulator of cellular migration and proliferation. (5, 6)

Colostrum also plays an important role in developing the neonate immune system and the presence of closely homologous bioactive components in bovine colostrum prevents infectious diseases in humans. (7, 8) The immune-boosting effects of colostrum are mostly due to its high concentration of the antibodies IgA and IgG. (9, 10) Antibodies are proteins that fight viruses and bacteria. Research shows that colostrum supplements may be particularly effective in boosting immunity in elite athletes. One 12-week study in 35 adult distance runners found that taking a daily bovine colostrum supplement increased the amount of saliva IgA antibodies by 79%, compared to baseline levels. (11) The antimicrobial factors present in colostrum act to protect the neonate against infections, especially in the first weeks after birth. Proline-rich protein (PRP) from colostrum acts as regulatory substances of the thymus gland and improves or eliminates symptomatology of both allergies autoimmune diseases and lactoferrin from colostrum restores humoral immune response which is mediated by T cells and B cells. (12) Lactoferrin helps to prevent or shrink cancer cells. It prevents colon, bladder, tongue, esophagus, lung cancer.

Bovine colostrum proved to be beneficial in preventing immunodeficiency related diarrhea and also infectious diarrhea. The patient who was given a dose of hyperimmune bovine colostrum by direct duodenal infusion, fecal output decreased to less than 2 liters per day after 48 hours of treatment and the stools were formed and cryptosporidium parasite was absent. (13) In addition, twenty-nine AIDS patients who were treated for 10 days with 10g per day of a BC product concentrated for immunoglobulin were the average daily stool frequency decreased from 7.4 to 2.2 by the end of the 10-day treatment period. (14) Colostrum also plays a role in Rotavirus and Salmonella typhi infection protection as well as antibiotic-related diarrhea due to the presence of lactoferrin. Studies have shown that hyperimmune bovine colostrum, derived from cows immunized with rotavirus, can prevent rotavirus diarrhea when given passively. (15)

In addition, Bovine colostrum may strengthen gut and fight infections in the digestive tract. A human study shows that bovine colostrum may stimulate the growth of intestinal cells, strengthen the gut wall, and prevent intestinal permeability. (16, 17) Colostrum may help prevent gastrointestinal problems caused by non-steroidal anti-inflammatory drugs (NSAIDs). In a small study published in 2001, researchers found that colostrum helped protect against gastrointestinal damage caused by the long-term use of indomethacin (an NSAID typically used to treat osteoarthritis and rheumatoid arthritis). (18)

References: 

1. Sylvie F. Gauthier, Yves Pouliot, Jean-Louis Maubois. Growth factors from bovine milk and colostrum: composition, extraction and biological activities. Le Lait, INRA Editions, 2006, 86 (2): 99-125. 
2. Lee J, Kwon SH, Kim HM, Fahey SN, Knighton DR, Sansom A. Effect of a Growth Protein-Colostrum Fraction on bone development in juvenile rats. Biosci Biotechnol Biochem. 2008 Jan;72 (1): 1-6. 
3. Mero A, Miikkulainen H, Riski J, Pakkanen R, Aalto J, Takala T. Effects of bovine colostrum supplementation on serum IGF-I, IgG, hormone, and saliva IgA during training. J Appl Physiol (1985). 1997 Oct; 83 (4): 1144-51. 
4. Kelly PA, Djiane J, Postel-Vinay MC, Edery M. The prolactin/growth hormone receptor family. Endocr Rev. 1991 Aug; 12 (3): 235-51. /
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8. Shing CM, Peake J, Suzuki K, Okutsu M, Pereira R, Stevenson L, Jenkins DG, Coombes JS. Effects of bovine colostrum supplementation on immune variables in highly trained cyclists. J Appl Physiol (1985). 2007 Mar; 102 (3): 1113-22. 
9. Stelwagen K, Carpenter E, Haigh B, Hodgkinson A, Wheeler TT. Immune components of bovine colostrum and milk. J Anim Sci. 2009 Apr;87(13 Suppl):3-9.
10. McGrath, Brian A., Fox, Patrick F., McSweeney, Paul L. H., Kelly, Alan L. Composition and properties of bovine colostrum: a review. Dairy Sci. & Technolgy. 2016;96(2):133-158.
11. Crooks CV, Wall CR, Cross ML, Rutherfurd-Markwick KJ. The effect of bovine colostrum supplementation on salivary IgA in distance runners. Int J Sport Nutr Exerc Metab. 2006 Feb;16(1):47-64.
12. Bogstedt AK, Nava S, Wadström T, Hammarström L. Helicobacter pylori infections in IgA deficiency: lack of role for the secretory immune system. Clin Exp Immunol. 1996 Aug;105(2):202-4.
13. Ungar BL, Ward DJ, Fayer R, Quinn CA. Cessation of Cryptosporidium-associated diarrhea in an acquired immunodeficiency syndrome patient after treatment with hyperimmune bovine colostrum. Gastroenterology. 1990 Feb;98(2):486-9.
14. Stephan W, Dichtelmüller H, Lissner R. Antibodies from colostrum in oral immunotherapy. J Clin Chem Clin Biochem. 1990 Jan;28(1):19-23.15. Pacyna J, Siwek K, Terry SJ, Roberton ES, Johnson RB, Davidson GP. Survival of rotavirus antibody activity derived from bovine colostrum after passage through the human gastrointestinal tract. J Pediatr Gastroenterol Nutr. 2001 Feb;32(2):162-7.
16. Marchbank T, Davison G, Oakes JR, Ghatei MA, Patterson M, Moyer MP, Playford RJ. The nutriceutical bovine colostrum truncates the increase in gut permeability caused by heavy exercise in athletes. Am J Physiol Gastrointest Liver Physiol. 2011 Mar;300(3):G477-84.
17. Playford RJ, MacDonald CE, Calnan DP, Floyd DN, Podas T, Johnson W, Wicks AC, Bashir O, Marchbank T. Co-administration of the health food supplement, bovine colostrum, reduces the acute non-steroidal anti-inflammatory drug-induced increase in intestinal permeability. Clin Sci (Lond). 2001 Jun;100(6):627-33.
18. Playford RJ, MacDonald CE, Calnan DP, Floyd DN, Podas T, Johnson W, Wicks AC, Bashir O, Marchbank T. Co-administration of the health food supplement, bovine colostrum, reduces the acute non-steroidal anti-inflammatory drug-induced increase in intestinal permeability. Clin Sci (Lond). 2001 Jun;100(6):627-33.