Flaxseed Oil, and GLA = Bad

Discussion in 'Food and nutrition' started by Kev, Dec 7, 2003.

  1. Kev

    Kev Guest

    Below is a recent study demonstrating some of the differences between fish oil and flax. Below that
    is a study demonstrating some adverse effects from GLA in Borage oil, and presumably this could
    include Evening Primrose oil. Fish oil consistently demonstrates positive effects.

    Anyone care to comment on this?

    J Nutr. 1996 Sep;126(9):2130-40.

    Normal subjects consuming physiological levels of 18:3(n-3) and 20:5(n-3) from flaxseed or fish oils
    have characteristic differences in plasma lipid and lipoprotein fatty acid levels.

    Layne KS, Goh YK, Jumpsen JA, Ryan EA, Chow P, Clandinin MT. Nutrition and Metabolism Research
    Group, University of Alberta, Edmonton, Canada.

    The study assessed the effect of low doses of fatty acids from fish or flaxseed oil on plasma lipid
    concentrations in normal humans consuming diets with either high (0.87, n = 11) or low (0.48, n =
    15) dietary polyunsaturated/saturated fatty acid (P/S) ratios. The dose of (n-3) fatty acids
    reflected an (n-3) intake that could easily be attained by selection of foods in a normal diet. The
    individuals were initially supplemented with olive oil [35 mg 18:1/(kg body weight.d)], and then
    were randomly assigned to either flaxseed or fish oil [35 mg 18:3(n-3) or 35 mg 20:5(n-3) +
    22:6(n-3)/(kg body weight.d), respectively] treatments. Participants consumed each oil supplement
    for 3 mo. Blood samples were drawn for analysis at the end of each 3-mo period. Plasma
    triacylglycerol, total, LDL and HDL cholesterol concentrations, and lipoprotein fatty acid
    concentrations are shown. Fish oil reduced plasma triacylglycerol and increased lipoprotein
    levels of 20:5(n-3) and 22:6(n-3). The flaxseed oil did not alter plasma triacylglycerol level
    and produced small changes in 20:5(n-3) and 22:6(n-3) concentrations. Total, LDL and HDL
    cholesterol levels were not affected by either (n-3) fatty acid. Significant differences in
    plasma triacylglycerol concentrations and total and LDL cholesterol levels were found between the
    two dietary P/S groups after all oil treatment periods. Levels of 18:3(n-3),
    23:4(n-6), 20:5(n-3), and 22:6(n-3) in LDL were also different in high vs. low dietary P/S groups
    for all oil treatments and in the VLDL for the olive oil and fish oil supplementation. This study
    indicates that low intake of purified fish oil induces changes in plasma triacylglycerol,
    20:5(n-3) levels in VLDL, LDL, and HDL, and 22:6(n-3) levels in LDL and HDL that are apparent
    after 3 mo and which might influence atherogenicity of lipoprotein particles in normal
    free-living individuals. Publication Types:
    * Clinical Trial
    * Randomized Controlled Trial PMID: 8814201

    Endocr Regul. 2002 Nov;36(4):143-9.   Comparison of the extrapancreatic action of gamma-linolenic
    acid and n-3 PUFAs in the high fat diet-induced insulin resistance.

    Simoncikova P, Wein S, Gasperikova D, Ukropec J, Certik M, Klimes I, Sebokova E.

    Department of Biochemical Technology, Faculty of Chemical and Food Technology, Slovak University of
    Technology, 812 37 Bratislava, Slovakia. OBJECTIVE: The effect of dietary borage oil (rich in the
    gamma-linolenic acid [GLA]) on insulin sensitivity and lipid metabolism was compared with that of
    fish oil (rich in n-3 polyunsaturated fatty acids [PUFAs]) in high fat (HF) diet-induced insulin
    resistance (IR) of rats. METHODS: Male Wistar rats were fed ad libitum for 3 weeks a standard
    laboratory chow (Controls) or high fat diet consisting of 70-cal % fat. In addition, a group of rats
    was fed high fat (HF) diet where a part of saturated fat was replaced with fish oil as a source of
    n-3 PUFAs (HF+FO), or borage oil as a source of GLA (HF+GLA). In vivo insulin action was assessed by
    the euglycemic hyperinsulinemic clamp. Glucose, insulin, free fatty acids (FFA), triglycerides (Tg)
    and glycerol levels in blood and tissue depots were also measured. RESULTS: Increased levels of Tg,
    FFA and glycerol in circulation after HF diet were accompanied by their raised accumulation in
    insulin sensitive tissues. FO feeding lowered the concentration of all lipids in serum and prevented
    their accumulation in both tissues. On the other hand GLA supplementation into the high fat diet did
    not suppress increased levels of Tg, FFA and glycerol in circulation and tissue depots as well. FO
    feeding significantly reduced HF diet-induced in vivo IR, while GLA supplementation did not improve
    the in vivo insulin sensitivity in HF diet induced insulin resistance. CONCLUSIONS: 1. Substitution
    of FO into the high fat diet led to an improvement of in vivo insulin action; 2. this insulin
    sensitizing effect of FO was accompanied by a decrease of circulating Tg, FFA and glycerol levels in
    the postprandial state and by a lower lipid content in liver and skeletal muscle. 3. on the
    opposite, GLA treatment failed to improve in vivo insulin action; and 4. was associated with an
    adverse effect on lipid levels both in circulation and tissue depots. PMID: 12466014
     
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  2. On Sun, 07 Dec 2003 08:59:52 GMT, Kev <[email protected]> wrote:

    >
    >Below is a recent study demonstrating some of the differences between fish oil and flax. Below that
    >is a study demonstrating some adverse effects from GLA in Borage oil, and presumably this could
    >include Evening Primrose oil. Fish oil consistently demonstrates positive effects.

    GLA is the precursor of arachidonate and is converted immediately to that if there is low omega-3
    levels to inhibit the conversion. (Goes through DHGLA, 20:3(omega-6) from 18:3(omega-6)
     
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