| Food and Nutrition Q&A: | |
by Chelsy Leslie, RD, from the April 2003 newsletter
Soy foods, such as tofu, soymilk, roasted soybeans, and tempeh, are everywhere
these days. For years, vegetarians and health enthusiasts have been including
soy in their diets as a protein replacement for meats, poultry, and other animal-based
products. More and more people are giving soy a try, hoping to decrease saturated
fat in their diets, alleviate symptoms of menopause, or help with other health
problems.
The complex composition of nutrients and phytochemicals in soy give it many health-promoting properties. However, in some situations, it can be detrimental if used inappropriately, just like any other food. Researchers have been studying the affect of soy on heart health; colon, prostate, and breast cancers; thyroid function; mental capacity; and bone health. Let’s take a look at some of their findings in a few of these areas:
Heart Health
Soy foods are an excellent choice for a heart healthy diet. First of all, soy
is low in saturated fat – approximately 85% of the fat in soybeans
is unsaturated. Also, because it is a plant food, soybeans contain no cholesterol.
Soybeans contain all the amino acids essential to human nutrition, making
soy a “complete” protein. Therefore, the protein quality is just
as good as animal sources without the saturated fat and cholesterol. Many
human clinical trials have shown that soy can lower both total and LDL cholesterol,
therefore contributing to a decreased risk of heart disease.
Other components of soy are being investigated to determine if they play a role in heart health. For example, isoflavones (a type of phytochemical) in soy may reduce the oxidation of LDL cholesterol. The oxidation of LDL is a key event in the development of fatty deposits in artery walls. Isoflavones may also help prevent stiffening of the arteries.
Breast Cancer
Many studies have examined the relationship between soy intake and breast cancer.
This is one of the most confusing areas of soy research today. Some research
indicates soy may help protect against breast cancer by altering the metabolism
of estrogen and making estrogen less available to tissues. However, there
is concern that soy may actually be harmful to women with estrogen-sensitive
(ER+) breast cancer or to women at high risk of developing breast cancer.
Until more information is available, women with ER+ breast cancer should
avoid consuming soy in large amounts.
Thyroid Function
Some foods, including soy, contain compounds called goitrogens, which can
interfere with thyroid function. Research indicates this is only a problem
when iodine
intakes are inadequate. The solution, therefore, is to increase dietary iodine
rather than eliminating soy. This can easily be done by using a small amount
of iodized salt.
Bone Health
Soy can help keep bones strong and prevent osteoporosis. First, the calcium
in soybeans is absorbed well compared to some beans and vegetables. Tofu
made with calcium and soymilk fortified with calcium offer even more calcium
per serving than regular soybeans. In addition, soy’s weak estrogenic
effect may prevent bone loss. However, the role of soy in bone health is
still not entirely understood.
Soy may not be a miracle food, but it does appear to offer many health benefits in most individuals. To reap the benefits of soy, aim for two to three servings of soy foods each day and avoid supplements containing soy components such as isoflavones. Supplements may give a large amount of only one component, which may function differently without the other parts. If you have never tried soy before, start with some roasted soybeans for a snack, soymilk in a smoothie, or tofu cooked like ground meat for tacos. Enjoy!
Read another opinion about soy.
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