Soy: HOW SAFE IS IT?

By Malnig, Anita; Brown, Jordana

We pored ever the research and came up with some answers

Vegetarians and soy go together like, well, peanut butter and jelly-it’s hard to think of one without the other. And for a long time, as study after study showed increasing evidence of soy’s health benefits, vegetarians were sitting pretty, confident that their dietary choices were the best for their bodies. But in the late ’90s, a glimmer of doubt appeared, in rhe form of news that a component of soy might increase the risk of cancer, instead of the other way around. The confusion has only escalated since then, so let’s revisit the issue of soy’s health claims-before you start skipping your favorite soymilk smoothie.

Q:

Should I consume soy or not?

A:

Heed the calming words of David Grotto, RD, LD, a spokesman for the American Dietetic Association: “Incorporated as part of a well- rounded diet, soy’s great,”

Soy has no cholesterol and negligible saturated fat, very low carbs, reasonable calories and scads of protein. In fact, it’s a complete protein, which means that, like meat, it contains all eight essential ami no acids (the kind that can’t be made by the body, so you have to get them from food sources). No other bean or vegetable can make the same claim.

What makes some people jittery are components of soybeans called isoflavones. On a molecular level, a soflavones are similar to the female sex hormone estrogen-so similar that they can bind to estrogen receptors in the body. This has led to worries that eating too much soy could impart the breast cancer risks linked to high estrogen levels. (Research on this controversial topic is ongoing.)

Q

So are isoflavones good or bad?

A:

Significant evidence suggests isoflavones may cause thyroid trouble by interfering with an enzyme in a way that causes goiter (an enlarged thyroid gland). There is also some indication that isoflavones can reduce the body’s ability to absorb thyroid- replacement drugs. However, most healthy people aren’t really at risk because their intake of thyroid-protective compounds and foods (iodized salt or green, leafy vegetables, for example) is sufficient to counteract soy’s effect.

More worrisome are the theories that soy consumption can stimulate the growth of certain types of tumors.

Q:

But waii, isn’t soy a potent cancer figther?

A:

We said it s confusing. Isoflavones can either interfere with or complement the body’s own hormones. Most research indicates that soy’s isoflavones and antioxidants protect against cancer in a multitude of ways, from limiting the growth of blood vessels that feed cancer cells, to blocking free radicals, which can influence tumor growth. There’s even evidence that people who have hormone- sensitive cancers, like breast and prostate, benefit from soy.

A study led by the National Cancer Institute found that Asian American women who ate the most soy-based foods between ages 5 and 11 decreased their risk for breast cancer in adulthood by 58 percent, possibly because isoflavones can lead to a decreased sensitivity to cancer-causing agents in breast tissue. In November 2005, the International journal of Cancer reported that eating soy foods could help men cut their risk of prostate cancer by up to 30 percent. And a 2002 study of 500 Chinese women found that the participants with breast cancer had consumed less soy. “It’s a theory that’s not proven, but it’s getting more acceptance among researchers,” says Mindy Kurzer, PhD, a professor in the food science and nutrition department at the University of Minnesota.

The effects of soy’s phytoestrogens on women who are at genetic risk of developing breast cancer or who already have it remain unproven. In the absence of hard scientific proof. Grotto supports soy consumption by pointing to the health of Asian women. “Population studies suggest that cultures that have always had soy as a part of their diet have better long-term breast cancer survival rates than cultures that don’t, so my philosophy is that eating soy foods in moderation is fine,” he says.

Q:

What’s the story on soy and heart health?

A:

Just when we thought we could give you unqualified good news, in January 2006, the American Heart Association (AHA) reviewed 22 research trials and concluded that neither soy protein nor isoflavones are responsible for significant reduction in LDL (“bad”) cholesterol or blood pressure.

This contradicts studies in which isoflavones were found to decrease blood clotting (which leads to heart attacks and strokes) and to lower blood pressure and LDL cholesterol. For instance, consuming 4Og of soy protein daily (roughly two soy burgers, plus 3 cups of soymilk) brought down the blood pressure of 302 adults with high-normal or mildly elevated blood pressure, found a study published in the July 5, 2005 issue of Annals of Internal Medicine. Furthermore, when soy-based mealreplacement drinks were tested on obese adults, those who consumed them lost slightly more weight and had much lower LDL cholesterol levels than a comparison group that drank milkbased meal replacements. The research, led by James Anderson, MD1 professor of medicine at the University of Kentucky, was published in the June 2005 issue of the Journal of the American College of Nutrition. That’s why the AHA includes the caveat that soy foods can be beneficial to heart health if eaten in place of high-fat proteins like those in red meat.

Q:

I’ve also heard (hat soy can combat symptoms of menopause. Is that true?

A:

Women dogged by hot flashes may find some relief when soy is a part of their diet. Isoflavones can affect the body like hormone- replacement therapy, though on a more modest, and therefore safer, scale. Japanese women-known for regularly consuming soy-have significantly fewer hot flashes.

Postmenopausal women are also susceptible to developing osteoporosis, and that’s another health risk that soy can lower. Isoflavones may help retain bone mass, according to a 2004 study of pre- and postmenopausal Japanese women published in the journal Clinical and Experimental Pharmacology and Physiology. The women who took 40mg isofiavone tablets daily held on to more bone mass than those on placebos. But another study, published in the July 2004 issue of the Journal of the American Medical Association, found that a daily soy supplement did not slow loss of bone mass in post- menopausal women over 60.

Q:

So what’s the best way to reap soy’s benefits?

A:

Grotto recommends tofu, tempch, miso and edamame-the staples of soy-rich Asian diets. Fewer benefits are derived from “second- generation” products like soy hot dogs or soy ice cream, which contain little soy and lots of other ingredients.

And don’t worry about overdoing it: You’d get sick of eating soy foods long before you consumed potentially dangerous levels of isoflavones. Most nutrition experts agree that one to two servings per day (one serving is 1 cup soymilk, cup edamame or cup tofu, which generally translates to 30-40mg isoflavones) will provide plenty of health benefits.

San Franctsco-based journalist Anita Malnig particularly enjoys kungpao tofu, a scallion-tofu dish with a spicy peanut sauce.

Nothing beats a bowl of warm edamame topped with a dash of salt for freelance writer Jordana Brown.

Copyright Active Interest Media Apr 2007

(c) 2007 Vegetarian Times. Provided by ProQuest Information and Learning. All rights Reserved.