EFFECT OF DIET ON PRODUCTION OF BUTYRATE BY THE HUMAN BREAST
The short chain fatty acid, butyrate, is known to be produced in the human large intestine as a result of fibre fermentation, and also in the breast as one of the fatty acids produced de novo during lactation. Recent research indicates that synthesis of fatty acids in the breast occurs only if the maternal diet is low in fat; with typical North American fat intakes, there is adequate fat supply from the mother to maintain milk fat content. In vitro, butyrate has been shown to be inhibitory against cell proliferation in many cancer cell lines, including breast and colon, and is therefore proposed as an anti- cancer agent. Its natural production may therefore represent protection against cancer in these organs. Butyrate is present in cow's milk but there has been little investigation of human milk. A study was therefore undertaken to identify and quantify butyrate in human breast milk, and to study the effect of diet on its production in the human breast. Twenty-five lactating women kept a record of their diet for a seven day period and expressed 20-50 mL breast milk on the last three consecutive days of the 7 day period. The milk was expressed between 1-2 p.m., using an Egnell breast pump. Samples were immediately frozen and maintained at -70°C until analyzed. One mL of thawed milk was deproteinised using 10% sulphosalicylic acid, followed by vacuum transfer over liquid nitrogen into 250 µL 0.5M NaOH for approximately one hour. The distillate was freeze-dried overnight. Samples were acidified using 100 µL orthophosphoric acid and immediately injected onto a 30 metre, 0.25mm i.d. acid modified polyethylene glycol capillary column on a Perkin Elmer Siyiva 2000 gas chromatograph, with Helium as the carrier gas. 2-Methylvalerate was used as the internal standard. Diet records were analyzed using the NUTS computer program. The mean (± S.E.M) intake of energy was 2238 ± 114 kcals/day. The mean(± S.E.M) fat intake was 32.1 ± 0.9 percent of energy. The mean(± S.E.M) intake of NSP(dietary fibre) was 14.6 ± 4.9 g/day. Butyrate was found in all milk samples tested, quantified for the first time with mean (± S.E.M) values being 14.4 ± 2.1 µmol/L. The mean(± S.E.M) fat content of the breast milk was 4.1 ± 0.3 gram percent.
butyrate, human breast milk
Master of Science (M.Sc.)
Pharmacy and Nutrition