The effect of fish oil supplementation on plasma α-tocopherol, retionol, lipid and lipoprotein levels in normolipidemic subjects

Influence of dietary long-chain n-3 fatty acids from Menhaden fish oil on plasma concentrations of -tocopherol in geriatric Beagles

OBJECTIVE

To determine effects of dietary n-3 fatty acids from Menhaden fish oil on plasma alpha-tocopherol concentrations in Beagles.

ANIMALS

32 female Beagles.

PROCEDURE

For 82 days, dogs were fed diets that contained 1 of 2 ratios of n-6:n-3 fatty acids (40:1 [low n-3] and 1.4:1 [high n-3]) and 1 of 3 concentrations of all-rac-alpha-tocopheryl acetate (low, 17 mg/kg of diet; medium, 101 mg/kg; and high, 447 mg/kg) in a 2 X 3 factorial study.

RESULTS

Diets high in n-3 fatty acids significantly increased total content of n-3 fatty acids in plasma (17.0 g/100 g of fatty acids), compared with low n-3 diets (2.02 g/100 g of fatty acids). Mean +/- SEM plasma concentration of cholesterol was significantly lower in dogs consuming high n-3 diets (4.59 +/- 0.48 mmol/L), compared with dogs consuming low n-3 diets (5.71 +/- 0.48 mmol/L). A significant interaction existed between the ratio for n-6 and n-3 fatty acids and amount of alpha-tocopheryl acetate in the diet (plasma alpha-tocopherol concentration expressed on a molar basis), because the plasma concentration of alpha-toco-pherol was higher in dogs consuming low n-3 diets, compared with those consuming high n-3 diets, at the 2 higher amounts of dietary alpha-tocopheryl acetate. Plasma alpha-tocopherol concentration expressed relative to total lipid content did not reveal effects of dietary n-3 fatty acids on concentration of alpha-tocopherol.

CONCLUSIONS AND CLINICAL RELEVANCE

Plasma alpha-tocopherol concentration is not dependent on dietary ratio of n-6 and n-3 fatty acids when alpha-tocopherol concentration is expressed relative to the total lipid content of plasma.

Fish oil supplementation with and without added vitamin E differentially modulates plasma antioxidant concentrations in healthy women

The purpose of this study was to assess the effect of fish oil with or without vitamin E on plasma vitamin antioxidants. Thirty-three apparently healthy women aged 18-28 yr were recruited from the university environs, and 30 completed the double-blinded, parallel design supplementation trial. Blood samples were collected at baseline (week 0) and following 28 d of supplementation with three capsules/d (0.8 g x 3) of either fish oil (FO) or FO with vitamin E (3 IU/g) (FOE). An additional blood sample was taken at day 91 (washout). Plasma antioxidant vitamins, fatty acid composition, and lipid peroxides were measured. Plasma alpha-tocopherol concentrations were increased significantly in both groups postsupplementation FO (P = 0.018) and FOE (P = 0.003) compared with baseline and washout values. Plasma retinol concentration was significantly increased (P = 0.034) compared with baseline and washout values following supplementation with FOE but not FO, while plasma beta-carotene was significantly increased (P = 0.036), compared with baseline and washout values, following supplementation with FO but not FOE. There was a trend (P = 0.059) toward decreased plasma ascorbic acid following FO supplementation compared with baseline and washout. Plasma lipid peroxides did not change following either supplementation. Results suggest that low-dose FO feeding with and without vitamin E differentially modulates plasma antioxidant vitamins but has no significant effect on lipid peroxidation.