Decreased Plasma Cholesterol Concentrations After PUFA-Rich Diets are not Due to Reduced Cholesterol Absorption/Synthesis
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Plasma cholesterol concentrations increase with consumption of high saturated fatty acid (SFA) and decrease with high polyunsaturated fatty acid (PUFA) diets, leading to shifts in lipid levels consistent with reduction in heart disease risk. Direct measurements of cholesterol absorption, one of the key regulators of plasma cholesterol levels, have not been performed in humans after consumption of high PUFA diets. Thus, cholesterol absorption and fractional synthesis rates (FSRs) were measured in 16 healthy adults (8 males and 9 females) using a randomized cross-over study with a diet containing high (PUFA/SFA) P/S ratio (2:1) and a low P/S ratio (0.5:1). Cholesterol absorption and fractional cholesterol synthetic rates were measured using stable isotopes after 20 days of dietary intervention. Diet did not affect cholesterol absorption or synthesis. There was a significant decrease in plasma cholesterol concentrations (P < 0.02), specifically LDL-cholesterol (P < 0.02), without a change in HDL-cholesterol or triacylglycerol concentrations. Intraluminal cholesterol solubilization and plasma sterol (cholesterol biosynthetic intermediates and plant sterols) levels were not affected by diet. Thus, consumption of diets with a high P/S ratio reduces plasma total and LDL-cholesterol concentrations independent of shifts in cholesterol absorption or synthesis.
KeywordsFatty acid Metabolic syndrome Cholesterol Bile Human PUFA SFA
Polyunsaturated fatty acid(s)
Ratio between polyunsaturated fatty acid and saturated fatty acid
Low density lipoprotein
High density lipoprotein
Saturated fatty acid(s)
Red blood cell
Cincinnati children’s hospital medical center
General clinical research center
Fractional synthetic rate
Gas liquid chromatography
We thank YenMing Chan, Richardson Centre for Functional Foods and Nutraceuticals, and Dr. Scot Harding, adjunct professor, Department of Human Nutritional Sciences, University of Manitoba for their help with the analytical part of the study. We also thank Suzanne Summer and the staff of the Body Composition Core of the General Clinical Research Center for their help with dietary management for the study. We were also supported by the National Institute of Health RR 08084 and DK 068463.
Conflict of interest
No authors have any conflict of interest with the current study.
- 15.Hernell O, Staggers JE, Carey MC (1990) Physical-chemical behavior of dietary and biliary lipids during intestinal digestion and absorption. 2. Phase analysis and aggregation states of luminal lipids during duodenal fat digestion in healthy adult human beings. Biochemistry 29:2041–2056PubMedCrossRefGoogle Scholar
- 57.Takeuchi H, Nakamoto T, Mori Y, Kawakami M, Mabuchi H, Ohishi Y, Ichikawa N, Koike A, Masuda K (2001) Comparative effects of dietary fat types on hepatic enzyme activities related to the synthesis and oxidation of fatty acid and to lipogenesis in rats. Biosci Biotechnol Biochem 65:1748–1754PubMedCrossRefGoogle Scholar