By:
Julie Bawden-Davis
Soy has enjoyed several glorious decades as a gastronomical wonder, hyped by many as a nutritional savior with the ability to cure and prevent diseases, including cancer and heart disease.
In recent years, however, science has taken a closer look, and some disturbing news about this age-old vegetable protein has emerged. Some reports have stated that soy can actually increase the risk of cancer, cause osteoporosis, thyroid problems, reproductive difficulties and even Alzheimer's Disease.
So what is the real truth about soy? Is it a miracle food or a health risk? Should you eat more soy? Less? What type of soy is best? Here's an overview:
History
Consumption of soybeans and soybean products dates back thousands of years. During the Chou dynasty (1134-246 B.C.), the Chinese discovered fermentation techniques leading to the more easily digested forms of soy we know today such as tempeh and miso.
Tofu was invented during 2nd-Century China. Soy finally made its way to Europe in the 1700s and the U.S. in the 1800s. Today the Midwest produces about half of the world’s soybean supply.
Nutritional Content
Soybeans come from a plant in the pea family and are especially high in protein, especially for a vegetable. A cup of mature soybeans contains 29 grams of protein, 10 grams of dietary fiber and 15 grams of fat, as well as a substantial amount of iron. Soybeans and products made from them are the richest sources of isoflavones available. Isoflavones are similar in structure to the female hormone estrogen and are also known as phytoestrogens.
Soy Sources
You’d be surprised at just how pervasive soy is in the American diet. While soy is obviously in foods like tofu, tempeh, edamame (whole soybeans) and soy milk, a surprising number of processed foods contain ingredients such as soy protein isolate, soy lecithin, soy flour and soybean oil.
It is important to point out that a consumer can't always know how much soy he or she is eating, because only some food products show how many grams of soy protein are in a serving.
Benefits
Because of its high protein content, soy is an ideal food for those choosing a vegetarian or vegan lifestyle. Soy offers the only complete source of vegetable protein and is comparable to eggs and meat. It contains all of the essential amino acids, as well as Omega-6 and Omega-3 fatty acids.
A number of major studies have discovered positive health benefits to enjoying your soy.
- Daily consumption of soy may lower LDL (“bad”) cholesterol levels up to 10 percent and reduce the risk of heart disease. According to the University of Maryland Medical Center, reducing your cholesterol with soy generally requires that you eat 31 to 47 grams of soy protein per day, although for overall heart health the U.S. Food and Drug Administration (FDA) suggests consuming 25 grams per day as part of a diet low in saturated fat and cholesterol.
- Soy may reduce symptoms of menopause, such as hot flashes and the risk of osteoporosis, although research results in these areas are mixed. The North American Menopause Society recommends 50 milligrams of soy per day for bone health and 40 to 80 daily milligrams to decrease hot flashes.
- The incidence of certain hormone-influenced cancers may be reduced by the consumption of soy, including breast cancer, endometrial cancer and prostate cancer, according to the National Institutes of Health.