Abstract
The effects of guar gum alone, or mixed with xanthan gum, on plasma and liver lipids were studied in rats fed high-sucrose diets. Rats were fed a high-starch diet (control diet), a high-sucrose diet (HS diet), or a HS diet supplemented with guar gum (HS-G diet) or a mixture of guar gum and xanthan gum (2:1, w/w, HS-GX diet) at 3% for 4 weeks. The plasma levels of glucose and insulin were not altered by intake of the HS, HS-G, or HS-GX diet. The plasma total cholesterol and plasma and liver triacylglycerol levels were elevated in rats fed the HS diet compared to rats fed the control diet, and were lowered to the control level in rats fed the HS-G or HS-GX diet. The HS-GX diet had a significantly more marked effect than the HS-G diet. Bile acids and lipids excreted in feces were increased in rats fed the HS-G or HS-GX diet, and the effects of the latter diet were significantly higher than those of the former. Fatty acid synthase activity in the liver, which was increased in rats fed the HS diet, was lowered in rats fed the HS-GX diet. The mechanism responsible for the cholesterol-lowering effect of the HS-GX diet was partly related to enhanced excretion of bile acids into feces, while that responsible for the hypotriacylglycerolemic effect was related to the decreased absorption of dietary lipids and decreased activity of fatty acid synthase in the liver.
