Animal studies demonstrated important lipid-lowering effects of soy isoflavones. Monkeys were fed soy isolates high in isoflavones and compared in a cross-over trial with a soy isolate in which the isoflavones had been removed via alcohol extraction. HDL ratios were significantly lowered, while HDL was significantly elevated in the group on the isoflavone-rich diet. No lipid lowering effect occurred in the group on a casein diet. Since they appear to have important phytoestrogenic effects, it is not unreasonable to believe soy isoflavones may prove to be protective.
Further investigation is warranted.
Dosage The amount of soy isoflavones in Asian diets is estimated to be in the range of 20-80 mg daily. Until more studies have been conducted on soy isoflavone extracts, the dosage necessary to provide protection from diseases such as cancer, cardiovascular disease, and osteoporosis remains speculative. Some recent concern has been raised regarding the safety of using soy products with infants and young children because of the phytoestrogenic constituents, including the isoflavones. While there has been no definitive answer to this question, millions of Asians have consumed large quantities of soy foods for hundreds of years without any apparent health risk and seemingly with health benefits. Long-term studies are needed to assess the potential beneficial or adverse effects of consuming phytoestrogens in the form of soy isoflavones early in life.