Differential Effects of Sphingomyelin Derived from Milk and Egg on Response to a High-fat Diet

Sphingomyelin (SM) has been shown to inhibit lipid absorption and is found in high levels in animal-derived foods such as egg and milk. Egg and milk SM differ in their fatty acid and sphingoid base composition, and therefore may have different biological effects on lipid metabolism. We evaluated the effects of egg and milk-derived SM on cholesterol metabolism in C57BL/6J mice. Mice were fed a high fat diet (45% kcal from fat, 21% milk fat by weight) (CTL, n = 10) or the same diet modified to contain 0.25% (wt/wt) of milk SM (MSM, n = 10), or 0.25% (wt/wt) of egg SM (ESM, n = 10). After 4 weeks, MSM had gained significantly less weight than CTL. ESM had significantly more epididymal adipose than the other groups. MSM significantly reduced serum cholesterol compared to both CTL and ESM groups, and reduced serum endotoxin compared to CTL. ESM had significantly higher levels of serum cholesterol, high-density lipoprotein cholesterol, free cholesterol, and phospholipid compared with the other two groups. Howev...