Soy is common in many Asian cuisines and is becoming increasingly popular in Western countries as many people aim for primarily plant-based diets. It offers many potential health benefits and is generally less expensive than meat.
However, you may have heard that soy is linked to cancer risk or that it may have a “feminizing” effect on men.
But what does the research actually say about this?
In fact, most research shows that eating a moderate amount of soy is unlikely to cause problems and may even provide benefits. All in all, you can safely include moderate amounts of soy foods in your Daily diet.
Does soy “feminize” men? not likely
Soy is rich in high quality protein and contains B vitamins, fiber, minerals and the isoflavones daidzein, genistein and glycitein.
Isoflavones are similar in structure to natural estrogens and are sometimes called “phytoestrogens” (phyto means plant). Soy isoflavones can bind to estrogen receptors in the body. They can act in a similar way to natural estrogen but with lots and lots of weaker effect.
Some studies have reported concerns, but these tend to relate to people consuming extremely high amounts of soy – such as a case report about a man with gynecomastia (enlarged breast tissue in men) who was found to be drinking almost three liters of soy milk a day.
As a literature review Notedmany other studies highlighting concerns in this area are based on animals trials or rare unique piece case (the case reports).
The same literature review Noted that if longer-term data in Western countries are needed, moderate amounts of soy in “traditional soy formulas provide modest health benefits with very limited risk of potential adverse health effects” .
What about soy and cancer risk?
One to study of 73,223 Chinese women over seven years found:
Women who regularly ate a large amount of soy foods during adolescence and adulthood had a significantly reduced risk of breast cancer. No significant association with the consumption of soy foods was found for postmenopausal breast cancer.
This could be due to the different types and amounts of soy consumed (as well as genetics).
Some animal testing and studies in cells show that very high doses of isoflavones or isolated soy protein can stimulate breast cancer growth, but that’s not easy in human trials.
A to study in Japanese men have reported a high consumption of miso soup (1-5 cups per day), may increase the risk of gastric cancer.
But the authors also said:
We thought other ingredients in miso soup might also play a role. […] For example, high concentrations of salt in miso soup could also increase the risk of gastric cancer.
What about heart health?
Soy contains isoflavones, healthy fats like polyunsaturated fats, fiber, vitamins and minerals, and is also low in saturated fat.
Swapping meat in the diet with soy products will reduce the amount of saturated fat you eat while increasing intake of important nutrients.
A to study with nearly half a million Chinese adults without cardiovascular disease, showed that those who ate soy four or more days a week had a significantly lower risk of death from heart attack than those who never ate it.
Replacing red meat with plant proteins, including soy products, has been associates with a lower risk of developing heart disease.
Moderate intake is good
If you want to include soy in your diet, choose whole soy foods like calcium-fortified soy beverages, tempeh, soy bread, tofu, and soybeans over highly processed foods high in salt and in saturated fat.
Soy research is ongoing and we still need it long term data on intakes in Australia and health benefits.
Overall, however, moderate amounts of soy foods can be eaten as part of a healthy diet and may even help relieve some symptoms of menopause.
According to the Victorian government Best Health Channel:
one or two daily servings of soy products can be beneficial to our health.
Harvard University School of Public Health said soy:
can be safely eaten several times a week, and probably more often, and is likely to have health benefits, especially when eaten as an alternative to red and processed meat.
So don’t worry too much about the soy milk in your coffee and tea or the tofu burger for lunch.
