How eating soy may help your health

Once enjoyed mainly by vegetarians, soy has become increasingly popular as consumers pursue healthier lifestyles. As research continues on the effects of soy, here are some ways you may benefit from this versatile plant.

Soybeans are one of the most nutritious and versatile plant foods available.

Soy contains:

• more protein than beef
• more calcium than milk
• more lecithin than eggs
• more iron than beef
• all of the essential amino acids, making it the only plant protein that approaches or equals animal products in providing a complete source of protein. This makes it a terrific choice for those looking for alternatives to meat products. Soybean oil is also low in saturated fat, unlike the fat from animal sources
• a good source of B vitamins and potassium, zinc, and other minerals
• important phytochemicals, including isoflavones, saponins, lignans and phytosterols, all of which have a variety of positive effects on the health

The beneficial effect of soy foods on heart disease, some cancers, osteoporosis and meno­pausal symptoms is the focus of much research. There is a great deal of epidemiological evidence (studies of populations) supporting the health-protective effects of soy. For example, populations that include high amounts of soy in their diet have low rates of breast cancer, prostate cancer and menopausal symptoms. However, the evidence is stronger for some health benefits than for others.

This is where the research is conclusive. A large body of evidence indicates that replacing some animal products with soy protein can reduce the risk of heart disease. This is because soy lowers levels of the artery-clogging LDL (low-density lipoprotein) cholesterol without reducing levels of the beneficial HDL (high-density lipoprotein) cholesterol.

The evidence is so convincing that the U.S. Food and Drug Administration recently gave food manufacturers permission to put labels on products that are high in soy protein indicating that these foods may help lower the risk of heart disease.

Throughout Asia, where soy has long been a dietary staple, the rates of breast and prostate cancer are much lower than in Western countries.

• Epidemiological studies of Asians show that it is soy intake early in life that is protective
• Soy foods contain compounds called iso­fla­vones, which are a subclass of a much larger group of food components called flavonoids
• Some researchers attribute the low incidence of these cancers to these isoflavones, which reduce the effects of estrogen on breast and prostate tissue
• Estrogen is thought to stimulate tumour growth in genetically susceptible people

However, the evidence regarding soy and its effect on cancer rates is still inconclusive, and much more research needs to be done. While there is evidence that soy plays a role in preventing breast cancer, the jury is out on its effect in women who have the disease. The recommendation is that they should consume soy in moderation and not increase their intake in response to a diagnosis of breast cancer.

Recent research has in­dicated that soy iso­fla­vones may delay bone loss and might even build bone density. Not all research is consistent in this finding, however, with some studies showing no effect of soy on bone loss.

For some women, diets rich in soy foods can reduce menopausal symptoms, particularly the frequency and severity of hot flashes. The extent of improvement, however, varies from woman to woman.

The consumption of soy foods has risen steadily, bolstered by growing evidence of the many health benefits of these versatile foods. Research continues, however, as some questions about soy and its health effects remain unanswered.