The contrasting effects of a dietary soya lecithin product and corn oil on lipoprotein lipids in normolipidemic and familial hypercholesterolemic subjects

Abstract

The effect of 36 g per day of an oral soya lecithin product (LEC), supplementing an ad libitum diet, on the plasma lipoprotein lipid levels of 12 subjects with normolipidemia and 6 with hypercholesterolemia was evaluated and compared with the effect of 30.5 g corn oil (CO), containing polyunsaturated fatty acids (PUFA) equivalent to those in the LEC, to determine whether the PUFA content of the LEC was responsible for changes in the lipoprotein lipids. High density lipoprotein cholesterol (HDL-CH) was increased by LEC (normolipidemics, n = 12 : ↑ 4.4 ± 2.0% ( x ± SEM), P < 0.05; hypercholesterolemics, n = 6: ↑ 8.7 ± 2.4%, P < 0.02) but was not changed by CO. Low-density lipoprotein cholesterol (LDL-CH) was reduced significantly by CO (normolipidemics: ↓ 12.3 ± 2.3%, P < 0.002; hypercholesterolemics: ↑ 9.8 ± 1.5%, P < 0.002) and reduced to a lesser extent by LEC (normolipidemics: ↑ 6.2 ± 1.3%, P = < 0.05; hypercholesterolemics: ↑ 4.4 ± 4.5%, 0.4 < P < 0.5). Total cholesterol (T-CH) was not modified as a result of taking LEC, because of opposite HDL- and LDL-CH responses, but was reduced as a result of taking CO (normolipidemics: ↓ 8.4 ± 1.2%, P < 0.002; hypercholesterolemics: ↑ 6.2 ± 1.5%, P < 0.01). The T-CH/HDL-CH ratio was decreased by approximately the same amount as a result of taking LEC (normolipidemics: ↑ 7.2 ± 1.5%, P < 0.002; hypercholesterolemics:↑ 9.2 ± 3.7%,0.05 < P < 0.1) and CO (normolipidemics: ↓ 7.8 ± 2.0,0.05 < P < 0.10;hypercholesterolemics:↑ 9.5 ± 2.1%, P < 0.001). The triglycerides were generally reduced in normolipidemics taking either supplement but were increased in hypercholesterolemics taking LEC and not changed in those taking CO. The hypercholesterolemics also increased their body weight when taking LEC ( P < 0.05). We conclude that LEC may increase HDL-CH by a mechanism independent of its PUFA content, whereas the PUFA content of both LEC and CO may alter the LDL-CH levels.