Dose effect of alpha-linolenic acid on lipid metabolism in the hamster.
In order to meet dietary requirements, the consumption of alpha-linolenic acid (ALA, 18:3 n-3) must be promoted. However, its effects on triglyceride (TG) and cholesterol metabolism are still controversial, and may be dose-dependent. The effects of increasing dietary ALA intakes (1%, 10%, 20% and 40% of total FA) were investigated in male hamsters. ALA replaced oleic acid while linoleic and saturated FA were kept constant. Triglyceridemia decreased by 45% in response to 10% dietary ALA and was not affected by higher intakes. It was associated with lower hepatic total activities of acetyl-CoA-carboxylase (up to -29%) and malic enzyme (up to -42%), which were negatively correlated to ALA intake (r(2) = 0.33 and r(2) = 0.38, respectively). Adipose tissue lipogenesis was 2-6 fold lower than in the liver and was not affected by dietary treatment. Substitution of 10% ALA for oleic acid increased cholesterolemia by 15% but, as in TG, higher ALA intakes did not amplify the response. The highest ALA intake (40%) dramatically modified the hepatobiliary metabolism of sterols: cholesterol content fell by 45% in the liver and increased by 28% in the faeces. Besides, faecal bile acids decreased by 61%, and contained more hydrophobic and less secondary bile acids. Thus, replacing 10% oleic acid by ALA is sufficient to exert a beneficial hypotriglyceridemic effect, which may be counteracted by the slight increase in cholesterolemia. Higher intakes did not modify these parameters, but a very high dose resulted in adverse effects on sterol metabolism.
Morise
Anne
A
Laboratoire de Physiologie de la Nutrition, Bât. 447, Université Paris-Sud, Orsay, France.
Mourot
Jacques
J
Riottot
Michel
M
Weill
Pierre
P
Fénart
Evelyne
E
Hermier
Dominique
D
D000818:Animals; D002784:Cholesterol / Q000097:blood / Q000378:metabolism; D006224:Cricetinae; D004042:Dietary Fats, Unsaturated / Q000008:administration & dosage* / Q000009:adverse effects; D004305:Dose-Response Relationship, Drug; D005243:Feces / Q000737:chemistry; D050356:Lipid Metabolism; D008099:Liver / Q000201:enzymology* / Q000378:metabolism; D008297:Male; D008647:Mesocricetus; D009751:Nutritional Requirements; D011897:Random Allocation; D014280:Triglycerides / Q000097:blood / Q000378:metabolism; D017962:alpha-Linolenic Acid / Q000008:administration & dosage* / Q000009:adverse effects
D004042:Dietary Fats, Unsaturated; D014280:Triglycerides; D017962:alpha-Linolenic Acid; D002784:Cholesterol