The phytoestrogens in both soy and flaxseed could help fight obesity and diabetes, according to studies presented last week at the meeting of the American Physiological Society.
Previous studies have suggested that soy, as a source of dietary protein, can have significant anti-obesity effects. With this in mind, a team of scientists led by Sam J. Bhathena of the Phytonutrients Laboratory at the US Department of Agriculture, carried out a study of the effects of both soy and flaxseed on rats.
Lean and obese rats were fed diets containing either 20 per cent casein or 20 per cent isolated soybean protein or 20 per cent flaxseed meal for 26 weeks. The lean rats were hypertensive while the obese rats showed symptoms of type II diabetes. Obese rats had significantly higher levels of plasma glucose, triglycerides, total cholesterol, HDL and LDL cholesterol.
Bhatena's team discovered that both the lean and obese rats fed with soybean showed a significant decrease in total cholesterol and LDL levels, although glucose levels were not affected. The flaxseed, on the other hand, decreased total cholesterol and triglycerids in both lean and obese rats, but significantly decreased HDL and LDL cholesterol levels only in obese rats. Flaxseed also decreased glucose in lean but not in obese rats and it had greater effect on various parameters than did soybean.
Both the soybean and flaxseed affected plasma lipids and a number of enzymes. They also had varying effects on tissue weights in lean and obese rats. Obese rats compared to lean rats had significantly lower plasma creatinine but higher total bilirubin, blood urea nitrogen, alanine aminotransferase and lactate dehydrogenase. Both soy and flaxseed meal decreased total bilirubin, protein and uric acid in the lean rats, but the effects in obese rats were mixed.