Highly controversial, soy is often touted as a protein-rich wonder food able to rescue humans from our dependence on meat and prevent heart disease. Yet for others, soy is no more than a hyped-up marketing ploy created by an industry determined to mislead gullible consumers for the almighty dollar. Nevertheless, over the past two decades soy and soy by-product consumption has dramatically increased — and so have numerous diseases.
Some studies suggest too much soy in the diet can reduce fertility in women, trigger premature puberty and disrupt development of fetuses and children. And now, men too may be negatively affected by consuming soy. A new study finds that isoflavones — compounds that mimic the female sex hormone estrogen — may be linked to cancer in men. Here’s why men should think twice about including soy in their diet.
1. Increases your risk for advanced prostate cancer
One out of seven men will be diagnosed with prostate cancer during his lifetime suggests the American Cancer Society. In fact, this year alone 161,360 new cases of prostate cancer will be diagnosed in the U.S. and about 26,730 men will die from the disease. Prostate cancer is the most common cancer among men in the U.S. One reason for this could be a diet high in soy.
A new study recently published in the International Journal of Cancer found that including isoflavones in the diet may influence the risk of developing prostate cancer. Isoflavones found in soy are a type of phytoestrogen. These plant-derived compounds have similar effects on the body as the female sex hormone estrogen. Soy and soy byproducts contain the highest concentrations of isoflavones.
To find out whether isoflavones actually influence the risk of prostate cancer, researchers analyzed the data of 27,004 men, all part of the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial.
Among the group, they found 2,598 men with prostate cancer over a median follow-up period of 11.5 years. Of these men, 287 had advanced prostate cancer. During the trial period, the men completed food frequency questionnaires. This data was used to assess the men’s intake of foods rich in isoflavones.
Compared to men who did not consume isoflavones in their diet, those who did were found to have a greater risk of developing advanced prostate cancer — cancer that has spread from the prostate gland to distant sites. Researchers concluded that isoflavones in the diet may affect a man’s risk of developing prostate cancer.
2. Soy may harm fertility in men
There has been a lot of interest in the possible hormonal effects of soy consumption in both women and men. But for men, the concern is that consuming phytoestrogens might cause adverse effects on fertility, mainly lowered testosterone levels and semen quality. Male fertility has been on the decline for men in North America, Europe, Australia and New Zealand — even plunging to record lows, according to a new analysis.
Meanwhile, the soy industry is racking up billions in sales each year with soy-based products finding their way onto most American tables. In fact, according to soyfoods.org, 31 percent of Americans consume soy foods or soy beverages knowingly or unknowingly once a week or more.
But eating even small amounts of soy foods and soy isoflavones may reduce a man’s sperm concentration, reports a study published in the journal Human Reproduction. Out of 99 men enrolled in the study, those who ate the most soy — an average of one serving every other day — had significantly lower sperm concentrations than those who reported not eating soy.
Soy contains estrogen-mimicking compounds, which have long been tied to infertility in animal studies. On average, men who ate soy had 41 million fewer sperm per milliliter than those who avoided it. So, if you already have low sperm count, you may want to consider eliminating soy from your diet.
3. Most soy grown in the U.S. is genetically modified
If you’re a critic of genetically modified foods (GM), you may want to avoid soy altogether. But that may prove difficult for the average person, since 91 percent of all soy grown in the U.S. is GM, according to WWF Global. In fact, soy protein, oil and processed soy ingredients make soy one of the most common foods in our diet. Even if you’re a conventional meat, egg or dairy eater, the animals those foods come from are being fed lots of GM soy.
Your best bet is to read ingredient labels each time you buy a product. Possible sources of soy include:
- Mono-diglyceride
- Baked goods, baking mixes and breaded foods
- Bean sprouts
- Beverage mixes
- Taco fillings
- Canned tuna, imitation crab and minced hams
- Chewing gum, candies, chocolate bars,
- Energy bars and protein bars
- Cooking spray, vegetable shortening, and vegetable oil
- Margarine
- Deli meat and processed meats
- Diet drinks and soy milk
- Dressings, gravies and marinades
- Monosodium glutamate (MSG)
- Processed deli meats and burgers and hotdogs
- Vegetarian meat substitutesSoy, teriyaki and Worcestershire sauce
- Seasonings
- Soups, broths and soups mixes
- Dips, mayonnaise and peanut butter
- Vegetarian dishes
Obviously, with soy dominating the U.S. market, it may prove almost impossible to avoid it altogether. But here’s what you can take away from this: read labels and avoid processed products that contain soy. Instead, choose a diet filled with whole organic foods and healthy fats. Only then can you be certain that soy won’t impact your health negatively.
— Katherine Marko
