Journal Name:
Am J Clin Nutr
Article Title:
Plasma cholesterol-predictive equations demonstrate that stearic acid is neutral and monounsaturated fatty acids are hypocholesterolemic
Date Written:
1995
Volume:
61
Number:
Page:
1129
Author(s):
Yu, S.; Derr, J.; Etherton, T.; Kris-Etherton, P.M.
Article:
Decades of research have investigated the effect of dietary lipids on blood cholesterol levels and have consistently demonstrated that saturated fatty acids (SFA) are hypercholesterolemic, whereas both monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) decrease plasma total cholesterol concentrations. More recent studies have suggested that stearic acid, an 18-carbon SFA, has a cholesterolemic effect clearly different from other long-chain SFAs. Despite findings that stearic acid is a unique SFA, it is still grouped with other SFAs in studies designed to develop serum cholesterol predictive equations. The present study was conducted to comprehensively examine the effects of stearic acid, MUFAs, and other fatty acids on total and lipoprotein cholesterol concentrations in both men and women.
Following an exhaustive literature search of controlled feeding studies published between 1970 and 1993, eighteen studies were selected in which the effects of dietary fatty acids on plasma lipids (PL) and lipoproteins (LP) were examined. Based on these data, new regression equations to predict the responsiveness of serum lipids and LP to individual dietary fatty acids in both men and women were developed.
Collectively lauric, myristic, and palmitic acids significantly increased total, LDL-C, and HDL-C concentrations. When analyzed together, these SFAs increased total cholesterol twice as much as PUFAs decreased these values. Myristic acid is five to six times more hypercholesterolemic than either lauric or palmitic acid. Stearic acid, in contrast, did not increase plasma total and LDL-C values but did lower HDL-C in women when compared to men. MUFAs were found to significantly decrease serum total and LDL-C, and appear to increase HDL-C concentrations. The effect of MUFAs on serum total and LDL-C appears to be dependant on the amount of SFA in the diet. At low levels of dietary SFA, a cholesterol lowering effect of MUFAs is observed. At high dietary levels of dietary SFA, the cholesterol lowering effect of MUFAs appeared to be obscured, exerting a neutral cholesterolemic effect. PUFAs were found to significantly decrease both total and LDL-C, and were not found to decrease HDL-C concentration.
Stearic acid should be distinguished from other long chain SFAs in plasma cholesterol predictive equations as it appears to be neutral in its effects on serum cholesterol and LDL-C. Further studies are also required to clearly elucidate the effect of stearic acid on HDL-C in women versus men. Canola oil is very unique amongst vegetable oils. As this data indicates, only 4% of the fatty acid composition as myristic acid in canola could potentially raise serum cholesterol levels. The remaining fatty acids - oleic, linoleic and linolenic - are hypocholesterolemic while stearic acid has no cholesterolemic effect., ,
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