Effects of dietary intake of gamma-linolenic acid on blood lipids and phospholipid fatty acids in healthy human subjects.

Abstract

SummaryThe effects of a dietary intake of gamma-linolenic acid 18: 3 n-6 (GLA) on blood lipids and phospholipid fatty acids were studied in 25 healthy men. The study was conducted over 4 one-month periods during which the subjects maintained their usual diet of about 2,780 kcal per day consisting of 54.4% carbohydrates, 13.5% proteins, and 32.1% lipids, the last of which included 13% in the form of vegetable oils (40g) and 328 mg of cholesterol. The vegetable oil, the only parameter which was varied during the study, was soybean oil during the 1st and 4th periods, not providing GLA, and rapeseed oil and evening primrose oil in the proportion of 2 : 1 during the 2nd period, providing 1.1 g of GLA per day, and I : I during the 3rd period, providing 1.6 g of GLA per day. The intake of other fatty acids was maintained as constant as possible throughout the study. The administration of GLA was accompanied by a dose-dependent reduction in LDL cholesterol (-10% with 1.1 g of GLA and -25% with 1.6 g of GLA) and a significant increase in HDL cholesterol (+7 and +9%, respectively). Triglycerides, phospholipids, and apoprotein B did not vary significantly, while apoprotein AI was markedly increased (+20 and +20%, respectively). In terms of the serum phospholipid fatty acids, the GLA ingestion was also accompanied by dose-dependent decrease in linoleic acid and increases in all its derivatives. Heterogeneous variations were observed in the n-3 derivatives: the 20: 5 n-3 was decreased but the 22: 5 n-3 and the 22: 6 n-3 remained stable. A decrease was observed for the 18 : 0 and the 24: 0, while the 18 : 1 n-9 was increased. These results indicate that dietary gamma-linolenic acid is more efficient in reducing serum LDL cholesterol than dietary linoleic acid.

Borage or primrose oil added to standardized diets are equivalent sources for γ‐linolenic acid in rats

“…Furthermore, a linear dose response in the increase of DHLA and GLA was observed in liver and erythrocyte phospholipids with both BO and EPO. This is in good agreement with results obtained in human studies (30,45). Ziboh and Fletcher (45), e.g., showed a dose-related increase of the DHLA content in human neutrophils of volunteers after supplementation with dietary BO.…”

“…Seeds of borage, evening primrose and black currant plants contain relatively large amounts of GLA. Several studies have shown that the application of GLA-rich oils results in the accumulation of GLA and its metabolite DHLA in tissue phospholipids (25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35). In previous studies, GLA-containing oils have been compared by *To whom correspondence should be addressed at F. Hoffmann-La Roche Ltd., VFEH, B.…”

Effects of Maternal Dietary n-3 and n-6 Fatty Acids (Pre- and Post- 6 Desaturation) on Tissue Glycerophospholipid Fatty Acid Compositions in Dams and Suckling Mice

“…On the other hand, GLA feeding as compared with LA feeding increased the levels of n-6 fatty acids, whereas it reduced those of n-3 fatty acids. These findings are consistent with the reports that 20511-3 is more readily converted to longchain n-3 metabolites and incorporated into glycerophospholipids than is 18:3n-3 (2 1-24), whereas 18:3n-6 as compared with 18:2n-6 is more readily converted into long-chain n-6 metabolites (25)(26)(27). Thus, dietary supplementation of post-A6-desaturase n-3 or n-6 fatty acids in place of their parent essential fatty acids significantly enhanced the incorporation of n-3 or n-6 fatty acids into glycerophospholipids in dam tissues.…”

Effect of Long-Term Dietary Supplementation of High-Gamma-Linolenic Canola Oil versus Borage Oil on Growth, Hematology, Serum Biochemistry, and N-6 Fatty Acid Metabolism in Rats

“…GLA (18:3 n-6), as compared to 18:2n-6, is even more effective in lowering plasma cholesterol in human and experimental animals (15,16,17). It has been reported that the effect of GLA intake on plasma total cholesterol and LDL-cholesterol is dosedependent in healthy humans (18). Huang et al (16) suggested that the hypocholesterolemic effect of GLA was exerted through enhancing the deposition of plasma cholesterol into liver.…”