The Pros and Cons of Soy: Jennifer Ozsungur RD featured in the Toronto Star
November 23, 2012
Soy milk and soy cheese are calcium-rich alternatives to dairy products for those with lactose allergies and intolerances.
Isoflavones, the plant estrogens found in soy, support good bone health and may reduce our risk of osteoporosis. Studies also show that isoflavones may reduce the severity and frequency of menopausal hot flashes, says University of Toronto nutritional sciences professor emeritus Lilian Thompson.
Rich in B vitamins, such as thiamine, riboflavin, niacin and folic acid, soy promotes energy, nerve and muscle function in the body. Soy also contains iron, for energy, and zinc, which is associated with healthy, shiny hair and skin, says Mississauga-based registered dietitian Jennifer Ozsungur.
Soy contains phytic acid, a chemical compound that reduces the risk of colon and breast cancer, Thompson says. But it binds to minerals, such as zinc and iron, reducing their availability to our bodies. Fermenting soy, a process that separates it into various molecules, also breaks down phytic acid, making minerals available to us.
And finally, soy slows starch absorption in our intestines, making us feel full longer.
CONS: HOLD THE SOY!
The benefits of isoflavones are in debate. Studies on Asian populations show that these weak estrogen mimickers have a protective effect against some cancers, Thompson says, while studies on North American populations show little or no effect. The differences, Thompson says, lie in how much soy both populations consume. Asians eat more soy and start in childhood. North Americans eat much less and usually begin eating it as adults.
Studies on animals have suggested that soy promotes tumour growth in certain tissues, prompting concern among some doctors. But recent epidemiological research on humans shows that despite worries, soy is safe and may even have a protective effect against breast cancer. The reason why? Humans and animals metabolize isoflavones differently, Thompson says. “The bottom line is that it’s safe.”
Some studies link soy with an increased risk of thyroid disease, but it’s too early to be sure — others show no connection, says Thompson.
We might believe that by eating tofu we’re reaping all the benefits of soy. But, tofu is a protein concentrate, meaning it may have less of soy’s beneficial minerals, vitamins, calcium and omega 3s.
Sometimes soy products are genetically modified. If you choose processed soy products, such as burgers, wieners or cold cuts, says registered dietitian Shauna Lindzon, you may not be getting all of soy’s beneficial compounds.
THE BOTTOM LINE
Everyone should include soy in their diet.
“It’s good food,” says Thompson. “Whole soy is high in fibre and a good source of protein.”
Pure soy is rich in vitamins, minerals, isoflavones, antioxidants and protein. Choosing soy in natural forms, such as edamame, roasted soy nuts, miso, sprouted tofu or tempeh, is the healthiest, most nutritious way to add it to your diet, says Lindzon.
“The more you manipulate soy, the more you lose,” she says, cautioning it’s important to limit consumption of processed soy products, such as energy bars, soy burgers, hotdogs or nuggets because the natural compounds are removed and ingredients such as sodium are added.
When it comes to breast cancer, like everything, soy is best eaten in moderation — one or two servings a day, Lindzon says. Limit concentrated sources of soy, such as soy-containing pills, powders or supplements and processed soy products.
The Dietitians of Canada say that to help prevent breast cancer, “soy foods should be eaten starting during childhood or adolescence.”
Lindzon recommends adding ½ cup of cooked soybeans to salad, soup or chili or snacking on ½ cup of cooked, shelled edamame. Boost protein in a smoothie by adding some soft tofu. Or add half a block of grilled tofu or tempeh to your salad or stir-fry, to get one serving of protein.
Original Post Date: Friday November 23, 2012
Author: Michele Henry