LOW LINOLENATE AND COMMERCIAL SOYBEAN OILS DIMINISH SERUM HDL CHOLESTEROL IN YOUNG FREE-LIVING ADULT FEMALES

Objective: A mutant soybean line (A16) low in linolenic acid content ( 2% of oil by weight) was developed to increase oil oxidative stability . It was unknown whether serum lipid and lipoprotein concentrations in humans would be affected should A16 soybean oil (A16 oil) replace com mercial soybean oil in diets. This study was conducted to examine the hypothesis that in free-living normolipidemic women, the consumption o f A16 oil at approximately 10% of energy intake (en%) would not affect serum lipids and lipoproteins differently than would the consumption of the same amount of a commercial soybean oil with 7% of linolenic ac id content. Design: Fifteen free-living female college students consum ed the soybean oils and coconut oil daily with regular meals for 9 wee ks in different orders, with each test oil being eaten for 3 weeks. Du ring the study, 13 en% was provided by each test oil and a total of 35 en% was from dietary fat. Serum concentrations of total cholesterol, high-density lipoprotein cholesterol (HDL cholesterol), low-density li poprotein cholesterol (LDL cholesterol) and triacylglycerides (TAG) we re measured. Serum total fatty acid patterns were analyzed as well. Re sults: Each of the three test oils decreased serum total cholesterol, LDL cholesterol and TAG concentrations from the baseline values. The f eeding of A16 and commercial soybean oils decreased serum HDL choleste rol significantly compared with coconut oil (p < 0.05). Dietary inclus ion of coconut oil increased serum myristic acid significantly more th an did either soybean oil (p < 0.01). Serum arachidonic acid concentra tions were significantly greater with A16 consumption than with commer cial soybean oil consumption (p < 0.001). Conclusion: A16 and commerci al soybean oils both diminished serum HDL cholesterol. Although the fa tty acid composition differed between the two soybean oils, A16 oil an d commercial oil had similar effects on serum concentrations of lipopr oteins and lipids. With increased oxidative stability, A16 oil is a go od alternative to commercial soybean oil.