Serum cholesterol predictive equations with special emphasis on trans and saturated fatty acids. An analysis from designed controlled studies

The effects of dietary trans fatty acids on serum total and low density lip oprotein (LDL) cholesterol have been evaluated by incorporating trans fatty acids into predictive equations and comparing their effects with the effec ts of the individual saturated fatty acids 12:0, 14:0, and 16:0. Trans fatt y acids from partially hydrogenated soybean oil (TRANS V) and fish oil (TRA NS F) were included in previously published equations by constrained regres sion analysis, allowing slight adjustments of existing coefficients. Prior knowledge about the signs and ordering of the regression coefficients was e xplicitly incorporated into the regression modeling by adding lower and upp er bounds to the coefficients. The amounts of oleic acid (18:1) and polyuns aturated fatty acids (18:2, 18:3) were not sufficiently varied in the studi es, and the respective regression coefficients were therefore set equal to those found by Yu et al. [Yu, S., Derr, J., Etherton, T.D., and Kris-Ethert on, P.M. (1995) Plasma Cholesterol-Predictive Equations Demonstrate That St earic Acid Is Neutral and Monounsaturated Fatty Acids Are Hypocholesterolem ic, Am. J. Clin. Nutr. 61, 1129-1139]. Stearic acid (18:0), considered to b e neutral, was not included in the equations. The regression analyses were based on results from four controlled dietary studies with a total of 95 pa rticipants and including 10 diets differing in fatty acid composition and w ith 30-38% of energy (E%) as fat. The analyses resulted in the following eq uations, where the change in cholesterol is expressed in mmol/L and the cha nge in intake of fatty acids is expressed in E%: A Total cholesterol = 0.01 Delta (12:0) + 0.12 Delta (14:0) + 0.05 7 Delta (16:0) + 0.039 Delta (TRAN S F) + 0.031 Delta (TRANS V) - 0.0044 Delta (18:1) - 0.017 Delta (18:2,18:3 ) and Delta LDL cholesterol = 0.01 Delta (12:0) + 0.071 Delta (14:0) + 0.04 7 Delta (16:0) + 0.043 Delta (TRANS F) + 0.025 Delta (TRANS V) - 0.0044 Del ta (18:1) - 0.017 Delta (18:2,18:3). The regression analyses confirm previo us findings that 14:0 is the most hypercholesterolemic fatty acid and indic ate that trans fatty acids are less hypercholesterolemic than the saturated fatty acids 14:0 and 16:0. TRANS F may be slightly more hypercholesterolem ic than TRANS V or there may be other hypercholesterolemic fatty acids in p artially hydrogenated fish oil than those included in the equations. The te st set used for validation consisted of 22 data points from seven recently published dietary studies. The equation for total cholesterol showed good p rediction ability with a correlation coefficient of 0.981 between observed and predicted values. The equation has been used by the Norwegian food indu stry in reformulating margarines into more healthful products with reduced content of cholesterol-raising fatty acids.