Consumption of cow milk and egg by lactating women and the presence of beta-lactoglobulin and ovalbumin in breast milk.

beta-Lactoglobulin and ovalbumin in mature human milk in healthy lactating Japanese women (n = 24) were determined by using an enzyme-linked immunosorbent assay. Subjects consumed > or = +200 mL cow milk/d for 1 wk before the sampling day and exactly 200 mL cow milk on the morning of the sampling day. beta-Lactoglobulin was detected (> 0.1 microgram/L) in breast milk in 15 of the 24 subjects (62.5%), with a maximum concentration of 16.5 micrograms/L. Ovalbumin was detected in only two subjects (8.3%) after the subjects followed their usual diet. beta-Lactoglobulin concentrations were low in the subjects whose cow milk consumption during the entire lactating period was low, even though all subjects consumed the same amount of cow milk before sampling. This result suggests that beta-lactoglobulin concentrations in breast milk are related to long-term consumption of cow milk. Amounts of food antigens in breast milk may be controlled by modifying the daily maternal diet.