The aim of the study was to incorporate
trans fatty acids into predictive equations for serum
cholesterol and compare their effects with the effects of the individual
saturated fatty acids 12:0, 14:0 and 16:0. We have introduced
trans fatty acids from partially hydrogenated
soybean oil (TransV) and
fish oil (TransF) into previously published equations by constrained regression analysis. Prior knowledge about the signs and ordering of existing regression coefficients were incorporated into the regression modelling by adding lower and upper bounds to the coefficients.
Oleic acid (18:1) and
polyunsaturated fatty acids (18:2, 18:3) were not sufficiently varied in the studies and the respective regression coefficients therefore set equal to those found by Yu et al. (Am J Clin Nutr 1995;61:1129-39).
Stearic acid (18:0) considered to be neutral was not included in the equations. The regression analyses were based on results from four controlled dietary studies with a total of 95 participants and including 10 diets differing in
fatty acid composition. The analyses resulted in the following equations where the change in
cholesterol is expressed in mmol/L and the change in intake of
fatty acids is expressed in E%: Delta Total
cholesterol = 0.01 delta(12:0) + 0.12 Delta(14:0) + 0.057 delta(16:0) + 0.039 delta(TransF) + 0.031 delta(TransV)- 0.0044 delta(18:1) - 0.017 delta(18:2, 18:3) and deltaLDL
cholesterol = 0.01 delta(12:0) + 0.071 delta(14:0) + 0.047 delta(16:0) + 0.043 delta(TransF) + 0.025 delta(TransV) - 0.0044 delta(18:1) - 0.017 delta(18:2, 18:3). The test set used for validation consisted of 22 data points from seven recently published dietary studies. The equation for total
cholesterol showed good prediction ability with a correlation coefficient of 0.981 between observed and predicted values. The equation has been used to reformulate margarines into "trans free" products all with more favourable effects on serum
cholesterol than previous products. Also a
cholesterol reducing
margarine has been produced. When tested against butter in an open clinical trial among subjects with mild
hypercholesterolemia the observed
cholesterol-lowering effect of this
margarine corresponded reasonably well with the predicted (0.77 vs. 0.64 mmol/L). We conclude that the equation has practical applicability and can be used to formulate and nutritionally optimise fat products as well as to evaluate already existing products on the market.