INCREASES IN DIETARY-CHOLESTEROL ARE ASSOCIATED WITH MODEST INCREASESIN BOTH LDL AND HDL CHOLESTEROL IN HEALTHY-YOUNG WOMEN

We studied the effects of dietary cholesterol intake on lipid and lipo protein levels in healthy young women (n=13) who were otherwise eating an American Heart Association (AHA) diet. The study used a randomized , three-way crossover design to determine the effects of 0, 1, or 3 eg gs added per day (dietary cholesterol range, 108 to 667 mg/d). Each of the three diets was eaten for 8 weeks, with a washout period between diets. Three fasting blood samples were obtained during the last 3 wee ks of each diet period to observe changes in fasting plasma lipid leve ls associated with the menstrual cycle. We also obtained blood just be fore and 4 and 8 hours after the subjects ingested a standard high-fat formula. During the menstrual cycle, total cholesterol and LDL choles terol levels fell by 0.051 mmol/L (1.99 mg/dL) and 0.064 mmol/L (2.48 mg/dL) per week, respectively. HDL cholesterol concentrations increase d by 0.060 mmol/L (2.3 mg/dL) per week during the first half of the cy cle and then fell by 0.050 mmol/L (1.94 mg/dL) per week during the sec ond half. Therefore, all statistical analyses were performed on values adjusted to midcycle. Total fasting cholesterol concentrations increa sed by 0.073 mmol/L (2.81 mg/dL) per 100 mg dietary cholesterol added to the diet per day (P=.001). LDL cholesterol increased by 0.054 mmol/ L (2.08 mg/dL) per 100 mg/d dietary cholesterol (P=.003); this account ed for about 75% of the rise in total cholesterol. HDL cholesterol con centrations increased by 0.015 mmol/L (0.57 mg/dL) per 100 mg/d dietar y cholesterol (P<.04). There was a wide range of responses among the w omen. Plasma apoB levels increased significantly, 0.93 mg/dL per 100 m g/d dietary cholesterol (P=.025), whereas apoA-I levels tended to rise (1.35 mg/dL per 100 mg/d,- P=.056). Increases in dietary cholesterol did not produce any observable effects on fasting plasma cholesteryl e ster transfer protein levels and had no effect on the response to a st andard high-fat formula. Although menstrual-cycle changes in plasma to tal, LDL, and HDL cholesterol levels were observed, the effects of the diets were similar in the follicular and luteal phases of the menstru al cycle. Additionally, despite changes associated with the menstrual cycle, within-subject variation in plasma total cholesterol was actual ly smaller in this study than in our study of young men.