Effects of varying maternal dietary cholesterol and phytosterol in lactating women and their infants

Abstract

Relationships between maternal cholesterol and phytosterol intake, and concentrations of cholesterol and phytosterol in maternal plasma, breast milk, and infant plasma were evaluated in 14 lactating mothers and their infants. The mothers took an ad libitum diet for 30 days after delivery and then were randomized to one of two diets: one containing 190 mg cholesterol and 1200 mg phytosterol per day, and a polyunsaturated/saturated fat ratio of 1.8; the second, a high cholesterol diet calculated to contain 520 mg cholesterol and 50 mg phytosterol/day, with a polyunsaturated/saturated fat ratio of 0.12. After 4 weeks on either diet, the mothers then crossed over to the other for a second 4 week period. Breast milk constituted the infants' sole intake during the two periods. During the ad libitum, low cholesterol-phytosterol enriched, and high cholesterol-low phytosterol diet periods, mean ± SE breast milk cholesterol (milligrams per grams total milk fat) was unchanged (2.4 ± 0.4, 2.4 ± 0.1, and 2.5 ± 0.2, respectively), despite a significant reduction of maternal plasma cholesterol from 220 ± 14 mg/dl (ad libitum) to 166 ± 7 (low cholesterol diet), and 186 ± 6 (high cholesterol diet). Infant plasma cholesterol, 143 ± 8 mg/dl on maternal ad libitum diet, was not significantly changed during maternal low cholesterol diet (140 ± 7), or during maternal high cholesterol diet (150 ± 8). Maternal milk phytosterol (0.17 ± 0.03 mg/g) on ad libitum diet, rose to 2.2 ± 0.3 on low cholesterol-phytosterol enriched diet, and fell to 0.7 ± 0.1 on the high cholesterol-low phytosterol diet, P < 0.0001. Maternal plasma phytosterol levels changed similarly, being 2.3 ± 0.9 mg/dl on ad libitum, 11.7 ± 0.9 on low cholesterol, and 4.9 ± 1.3 on high cholesterol intakes, P < 0.0001. Infant plasma phytosterol levels, 0.37 ± 0.04 mg/dl on both maternal ad libitum and high cholesterol intakes, rose to 0.54 ± 0.05 on maternal low cholesterol, phytosterol enriched diet (P < 0.01). Maternal dietary and plasma phytosterol levels were closely correlated (r = 0.62, P = 0.0001), as were plasma and milk phytosterol levels (r = 0.39, P = 0.02). Milk phytosterol and infant plasma phytosterol levels were also closely related (r = 0.43, P = 0.008). Conversely for cholesterol, the only significant maternal correlation was between dietary and plasma levels, r = 0.43, P = 0.004. No significant correlations were observed between maternal plasma and milk cholesterol levels, or between maternal milk and infant plasma cholesterol levels. On the polyunsaturate enriched as compared to a saturate enriched diet, milk content of linoleic acid was more than doubled, while oleic, palmitoleic, stearic, palmitic, and myristic acid levels were reduced.