CHEMICAL AND NUTRITIONAL STUDIES OF FLAXSEED (VARIETY LINOTT) IN RATS

The nutritional effects of flaxseed (Linum usitatissimum, variety Linott) were studied in the rat. In addition, thermal and storage stabilities of flaxseed were evaluated. Weanling rats were fed diets containing ground flaxseed at levels of 0, 10, 20, or 40% for 90 days. No differences were found in the food intake nor in body and organ weights. Serum triglyceride, total cholesterol, and the low-density lipoprotein (LDL) cholesterol concentrations were significantly lower in the rats fed the 20% and 40% flaxseed diets compared to the 0% flaxseed group. The high-density lipoprotein (HDL) cholesterol concentration and the LDL:HDL-cholesterol ratio were generally lower in the flaxseed-fed rats when compared to the 0% flaxseed group, but a significant lowering occurred only in the 40% flaxseed group. The incorporation of flaxseed in the diet caused significant elevations in the levels of the alpha-linolenic acid in adipose tissue and in organs. Higher amounts of eicosapentaenoic, docosapentaenoic, and docosahexaenoic acids were observed in the heart and liver of flaxseed-fed rats when compared to the 0% flaxseed group. A significant lowering of tissue vitamin E levels and an elevation of urinary thiobarbituric reacting substances occurred only in the 40% flaxseed group, which suggested that low to moderate intakes of flaxseed did not impart an oxidative stress on rat tissues. Dietary fiber in flaxseed appeared to be largely fermentable and was associated with a large increase in fecal moisture. The phytate in flaxseed had no effect on zinc, status. The oil in both the intact and the ground flaxseeds was found to be thermally and oxidatively stable.