gamma-linolenic-acid and Hypercholesterolemia

Nineteen hypercholesterolemic patients (10 without and 9 with hypertriglyceridemia) were given evening primrose oil rich in gammalinolenic acid (GLA, 18: 3n - 6), in a placebo controlled cross-over design, over 16 weeks (8 + 8 weeks), with safflower oil as the placebo. During supplementation with evening primrose oil, dihomogammalinolenic acid (20: 3n - 6) increased in plasma lipids and red blood cells, and in subjects without hypertriglyceridemia there was a significant decrease in low density lipoprotein-cholesterol and plasma apolipoprotein B compared with the levels observed during safflower oil administration. Our results confirmed that evening primrose oil is effective in lowering low density lipoprotein in hypercholesterolemic patients.

Topics: Adult; Apolipoproteins; Cholesterol; Dietary Fats, Unsaturated; Double-Blind Method; Fatty Acids, Essential; Female; gamma-Linolenic Acid; Humans; Hypercholesterolemia; Linoleic Acids; Linolenic Acids; Lipoproteins; Male; Middle Aged; Oenothera biennis; Phospholipids; Plant Oils; Random Allocation; Safflower Oil; Triglycerides

Hypercholesterolemia indirectly increases the risk for myocardial infarction by enhancing the ability of platelets to aggregate. Diets enriched with polyunsaturated fatty acids (PUFAs) have been shown to reduce the detrimental effects of cholesterol on platelet aggregation. This study investigated whether dietary hempseed, a rich source of PUFAs, inhibits platelet aggregation under normal and hypercholesterolemic conditions. Male New Zealand white rabbits were fed one of 6 dietary interventions: regular control diet (RG); control diet + 10% hempseed (HP); control diet + 10% partially delipidated hempseed (DHP); control diet + 0.5% cholesterol (OL); control diet + 0.5% cholesterol + 10% hempseed (OLHP); control diet + 5% coconut oil (CO). After 8 weeks, blood was collected to measure ADP- and collagen-induced platelet aggregation and plasma levels of fatty acids, cholesterol, and triglycerides. The hempseed-fed animals (HP and OLHP) displayed elevated plasma levels of PUFAs and a prominent enhancement in 18:3n-6 (gamma-linolenic acid, GLA) levels, a unique PUFA found in hempseed. The cholesterol-supplemented groups (OL and OLHP) had significantly elevated plasma levels of cholesterol and triglycerides, but platelet aggregation was significantly augmented only in the OL group. The addition of hempseed to this diet (OLHP) normalized aggregation. The direct addition of GLA to the OL platelet samples blocked the cholesterol-induced stimulation of platelet aggregation. The results of this study demonstrate that when hempseed is added to a cholesterol-enriched diet, cholesterol-induced platelet aggregation returns to control levels. This normalization is not due to a reduction in plasma cholesterol levels, but may be partly due to increased levels of plasma GLA.

Topics: Animals; Blood Platelets; Body Weight; Cannabis; Cholesterol Esters; Cholesterol, Dietary; Dietary Supplements; Disease Models, Animal; Fatty Acids, Unsaturated; gamma-Linolenic Acid; Hypercholesterolemia; Male; Platelet Aggregation; Platelet Aggregation Inhibitors; Rabbits; Seeds; Triglycerides

Topics: Antioxidants; Carya; Commiphora; Dietary Fats; Dietary Fiber; Fatty Acids, Essential; Fatty Acids, Omega-3; gamma-Linolenic Acid; Heart Diseases; Humans; Hypercholesterolemia; Hypolipidemic Agents; Linoleic Acids; Linseed Oil; Nutritional Sciences; Oenothera biennis; Patient Education as Topic; Phytotherapy; Plant Extracts; Plant Gums; Plant Oils; Soybean Proteins; Triglycerides

The effect of dietary supplementation with evening primrose oil (containing 70% gammalinolenic acid) on the concentration of plasma lipids and lipoproteins of the New Zealand White rabbit was investigated. No significant changes were observed in the concentrations of plasma cholesterol or triglycerides during the treatment, although an increase in high density lipoprotein (HDL) cholesterol (P < 0.01) was observed at 4 weeks of evening primrose oil intake and 2 weeks after withdrawal. However, when HDL subpopulations were resolved by gradient gel electrophoresis, major alterations were observed in the distribution of HDL subfractions. These included an increase in HDL2b (P < 0.001) and HDL3c (P < 0.001) and the appearance of very large particles of HDL. These findings suggest that supplementation of diets with n-6 fatty acids may be effective in the long-term prevention of atherosclerosis.

Topics: Animals; Arteriosclerosis; Cholesterol; Cholesterol, HDL; Diet; Fatty Acids, Essential; Female; gamma-Linolenic Acid; Hypercholesterolemia; Linoleic Acids; Linolenic Acids; Lipoproteins, HDL; Lipoproteins, LDL; Oenothera biennis; Plant Oils; Rabbits; Triglycerides