Influence of n-3 fatty acids on blood lipids in normal subjects.
Influence of n-3 fatty acids on blood lipids in normal subjects.
Year: 1989
Authors: T A B Sanders, A Hinds, C C Pereira.
Publication Name: J. Int. Med.
Publication Details: Volume 225; Number S1; Page 99.
Abstract:
In this paper, data from several studies is reported in which healthy volunteers consumed oils containing ALA, EPA and DHA for various periods. Following a test meal in which the oil was supplied by MaxEPA (18% EPA and 12% DHA) or by olive oil, a blunted increase in plasma TG was observed in subjects given fish oil compared to olive oil. Increases in EPA and DHA were reported in all lipid fractions with the largest increases found in the PL fraction. In longer term studies, the diets of subjects were supplemented with ALA as flaxseed oil or with MaxEPA for 2 weeks. The ALA diet increased EPA, but not DHA, in plasma PLs. The diets of another group of subjects were supplemented with MaxEPA for a 12 week period. In this group, the proportion of EPA in platelet lipids increased in a dose dependent manner. In another study, eight male subjects received 18 g of MaxEPA/day for 3 weeks. EPA and DHA from MaxEPA reduced plasma TG and VLDL-C levels. The effects of daily supplements of 20 ml of FO (5 subjects supplemented for 2 weeks) were compared with 10 g of fish oil (1.8g EPA and 0.4g DHA – 8 subjects supplemented for 3 weeks) and 6 g of TG fraction derived from fish oil (0.8g EPA and 2.2g DHA – 9 subjects supplemented for 3 weeks). Flaxseed oil had no effect on plasma lipid concentrations. Both fish oil fractions lowered plasma TG, but only the DHA rich supplement increased HDL-C and LDL apoB levels. TC and LDL-C levels were not affected by the n-3 PUFAs in any treatment. The authors concluded that ALA from plant sources and EPA and DHA from fish oils differ in their effects on blood lipids. The extent to which ALA is converted to EPA will depend upon the affinity of ALA for other metabolic pathways such as beta-oxidation as well as on the dietary intake of LA. Although this paper is cited in more recent investigations on ALA, it is difficult to draw conclusions as to the metabolic significance of ALA since several studies using different amounts of n-3 PUFAs for differing periods of time are compared in heterogeneous groups of subjects.
