Vitamin E in fortified cow milk uniquely enriches human plasma lipoproteins

Abstract

Background: Milk fat may contribute to atherogenesis in humans.

Objective: We sought to offset the atherogenic potential of milk fat by adding polyunsaturated fat and vitamin E to milk.

Design: We measured plasma lipids, lipoproteins, and tocopherol and LDL oxidation in normolipemic adults. In experiment 1 (n = 48), we compared delivery of 100 mg all-rac-alpha-tocopheryl acetate/d in capsules, skim milk, and 1%-fat milks containing soybean oil, milk fat, or both (1:1). In experiment 2 (n = 24), we compared delivery of natural (RRR-alpha-tocopheryl acetate) and synthetic (all-rac-alpha-tocopheryl acetate) vitamin E in milk with delivery of all-rac-alpha-tocopheryl acetate in orange juice (200 mg/d in each group). In experiment 3 (n = 7), we compared delivery of 30 mg all-rac-alpha-tocopheryl acetate/d in milks with and without added vitamins A and D.

Results: Enrichment of milk fat with soybean oil did not alter plasma lipoproteins. Microdispersion of vitamin E in milks increased the molar ratio of plasma tocopherol to cholesterol by >2-fold compared with the molar ratio after consuming vitamin E capsules, whereas the molar ratios were comparable after ingestion of orange juice and capsules. Synthetic and natural vitamin E performed comparably. The enhanced plasma vitamin E:cholesterol attributed to milk increased protection of LDL against oxidation. Vitamins A and D did not affect vitamin E delivery by milk.

Conclusions: Milk augments vitamin E transport by human lipoproteins at intakes of 100-200 but not 30 mg/d. This augmentation is independent of the presence and type of fat in milk, its vitamin A and D contents, and whether the vitamin E is natural or synthetic.