Is Soy Safe?

Soy has raised all kinds of concerns over the past few years. The number of scary rumors against it seems to equal the number of health claims for it. Both sexes seem to be hit with major concerns. For women soy has been connected to breast cancer risk while men fear that regular soy intake may lower testosterone.

The main culprit of concern and benefit is from isoflavones, a phytochemical found in soy. There is a lot of interest in isoflavones connection to breast cancer because they have an estrogen-like effect in the body. However, isoflavones also act as antioxidants, are anticarcinogenic and may boost the immune system.

Is Soy Safe? - 904FitnessFortunately, a lot of research has been conducted on soy’s connection to breast cancer and the results are positive. A 2009 review of 34 studies found that about half of the research showed that soy foods reduced breast cancer risk while the other half showed no impact. These studies looked at different sources of soy, isoflavone content and different cultures. The final conclusion is that the isoflavones in soy offer a protective effect against breast cancer.

Soy has also raised some concerns among males that it may lower testosterone levels and promote feminization. These fears have led many men to completely avoid it. This idea came from preliminary research that looked only at a soy dietary supplements and soy protein isolate. More recent studies have shown that dietary sources of whole soy have no negative effect on testosterone levels and may actually protect against prostate cancer.

One of the most important principles researchers agree on is that the type of soy you eat matters. Soy’s protective and health-promoting properties are found in the isoflavones and other phytonutrients. The more processed the source of soy (as in the less it looks like a soybean) the less, if any, isoflavones and phytonutrients it contains. Therefore, a veggie burger for example, may be a good choice for vegetarian protein but it’s doubtful that you will get the benefits of the isoflavones. Products like veggie burgers are a processed food and should be eaten in moderation like all the others.

Edamame, tofu, tempeh and miso are examples of whole or minimally processed soy foods. These are the best choices for both sexes and can be included safely in your daily diet. The Food and Drug Administration currently recommends 25 grams of soy protein a day and supports the claim that this may reduce your risk of heart disease. No such recommendation exists specific to any cancer, so it’s wise to continue to follow this guideline.

The following chart lists the soy protein amounts of common foods.

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Tofu, 4 oz
Edamame, 1/2 cup
Tempeh, 4 oz
Soymilk, 1 cup
Soy nuts, 1/4 cup
Soy crumbles, 1/3 cup
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Grams of Soy Protein


Jenna is a registered dietitian specializing in sports nutrition. As a healthy living speaker, nutrition counselor and media personality she enjoys helping people have a positive relationship with food and reach their goals. You can follow her fresh perspective on her blog at www.freshfoodperspectives.com or on Twitter at @JBraddockRD.

Jenna Braddock

Jenna Braddock

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