EFFECTS OF PARTIALLY HYDROGENATED FISH-OIL, PARTIALLY HYDROGENATED SOYBEAN OIL, AND BUTTER ON SERUM-LIPOPROTEINS AND LP[A] IN MEN

We have compared the effects of partially hydrogenated fish oil (PHFO- diet), partially hydrogenated soybean oil (PHSO-diet), and butterfat ( butter-diet) on serum lipids and lipoprotein[a] in 31 young men. The t hree test margarines, which contributed 78% of total fat in the diets, were produced from 70% of butterfat, PHSO, or PHFO, each with 30% of soybean oil. Fat provided about 35% of energy, and trans fatty acids 0 .9%, 8.5%, and 8.0% of energy in the butter-, the PHSO-, and the PHFO- diet, respectively. Dietary cholesterol was balanced by the addition o f dried egg powder to the PHSO-and the butter-diet; thus all diets con tained 420 mg dietary cholesterol per 10 MJ per day. The subjects cons umed all three test diets for 19-21 days in a random order (crossover design). The serum levels of total and LDL-cholesterol were significan tly elevated on the PHFO-diet (mean values 5.42 and 3.94 mmol/L, respe ctively) compared to the PHSO-diet (5.11 and 3.58 mmol/L, respectively ) but not different from those on the butter-diet (5.32 and 3.81 mmol/ L, respectively). LDL-cholesterol was significantly reduced on the PHS O-diet compared to the butter-diet. The level of HDL-cholesterol was s ignificantly lower on the PHFO-diet (0.98 mmol/L) when compared to the butter-diet (1.05 mmol/L) and with border-line significance compared to the PHSO-diet (1.05 mmol/L). The ratio of LDL- to HDL-cholesterol w as significantly higher on the PHFO-diet (4.20) when compared to both other test diets (3.85 and 3.65, respectively). No significant differe nces in triglyceride values were observed. Lp[a] increased and apoA-I decreased significantly after consumption of both the PHSO-diet and th e PHFO-diet, compared to the butter-diet. In conclusion, our results i ndicate that consumption of PHFO may unfavorably affect lipid risk ind icators for coronary heart disease at least to the same extent as butt erfat. To what extent the observed effects are due to the content of m onoene trans, diene trans, or to the long chain saturated fatty acids in PHFO remains to be elucidated.