The soybean (Glycine max) originated in China and has been cultivated there for over 13,000 years. It was first introduced into Japan before becoming popular in other Asian countries.
Soy food products come in many forms such as the traditional miso, tempeh, tofu, soy sauce and the more recently developed soy milk, soy flour, soy hot dogs, soy burgers and soy cheese.
The simple sugars raffinose and stachyose found in unfermented soy foods are not digestible and can cause flatulence and abdominal discomfort.
The health benefits of soybeans and soy foods include reduced LDL cholesterol, cancer prevention and reduced coronary artery disease risk.
Health Benefits of Soybeans
Soybeans are an excellent source of protein and molybdenum. They are a very good source of iron, calcium, phosphorus, and dietary fiber. They are a good source of vitamins B1, B2, B6, and E and folic acid. They also contain other health promoting compounds, including phytosterols, lecithin, isoflavones, phytoestrogens, and protease inhibitors. The amino acid profile of soy is a little low in methionine and tryptophan, but is still regarded as an excellent source of protein, soybeans (38% protein), soy flour (40 to 50% protein), soy protein concentrates (70% protein), and soy protein isolates (90 to 95% protein).
* Reduce LDL Cholesterol
Increased consumption of soy foods has been associated with reduction in LDL cholesterol in both clinical and observational studies. Human studies have also shown that soy protein is effective in lowering plasma cholesterol, LDL cholesterol and triglyceride concentrations.
In one 8-week randomized, placebo-controlled trial in 117 patients with high cholesterol levles, LDL cholesterol was significantly reduced by 5.9% after consuming 15-25g/day of soy protein.
A meta-analysis of thirty studies concluded that a daily dietary intake of 25g of soya protein resulted in small, highly significant reductions in total and LDL cholesterol (-6%)
A preparation combining isolated soy protein with soy fibers and phospholipids has been shown to have twice the lipid-lowering effect of a preparation containing isolated soy protein alone.