Question: I am hearing mixed reports about whether soy is good/bad for you. Wondering which is true? Should I add soy and/or replace some meat or milk with soy in my diet, or should I avoid it?
Answer: Conflicting data have confused many on the attributes of soy, a wonder food or bad news, which is it? Soy production in the U.S started to take off a hundred years ago, as a forage crop, for its oil and a replacement for meat due to its protein content. Soy was linked with populations in the Far East and associations were made between soy intake and the health benefits of people who consumed it.
Soy beans are a legume (bean family) and are an excellent source of protein and a good source of magnesium, iron, copper and fiber. Tofu is an excellent source of protein and calcium as calcium sulfate is used to coagulate soy milk curds into tofu, while the soy bean itself is not a good source of calcium. Soy milk is fortified with calcium, vitamins A, D and B12 and is similar in nutrition quality to cow’s milk. And no, chocolate soy milk does not come from chocolate colored soy beans!
We are encouraged to consume a more plant based diet and limit foods from an animal source, so it would seem prudent to limit meat and milk intake and switch to soy milk and tofu, right?
On to the controversies ...
One of the issues involves compounds found in soybeans that are chemically similar to the hormone estrogen and known as phytoestrogens, in particular a group called isoflavones. Several human cancers are linked to high levels of circulating human estrogen, for years women with breast cancer and men with prostate cancer were advised not to consume soy foods for fear that the plant estrogen would influence cancer growth. Early animal studies indicated that genistein (an isoflavone) increased growth of estrogen receptor positive breast cancer cells and thus promoted cancer.
However, the animal experience does not always replicate in the human body and now we know that rodent metabolism of phytoestrogens result in much higher circulating levels of the active form of isoflavone, more so than humans. Interestingly, ongoing soy research in women involves gut bacteria that metabolize isoflavones into a substance called equol. Women who make equol (courtesy of their specific gut bacteria) produce another form of estrogen that does not promote cancer growth.
Beneficial health properties connected with soy include lowering high cholesterol, easing gastro-intestinal issues and reduction in colorectal cancer. A small percentage of the population are allergic to soy protein and should avoid it.
Recommendations, including cancer survivors, suggest that consuming 1-3 servings of whole soy food a day is safe and may be good for you! This includes edamame, tofu, tempeh, and soy milk. As with all processed foods avoiding/limiting processed soy foods is suggested. To keep things in perspective, choosing the odd soy burger over a hamburger is not going to bring the ‘Food Police’ to your door.
Another ‘hot’ issue with soy is its GMO status. Around 90% of the soy grown in the U.S is genetically modified. To resolve that issue, eat only organic non GMO soy foods. There, that was easy!
However, I suspect that if you have concerns regarding GMO’s you are probably already reading food labels, and the foods that do not contain GMO’s will clearly state that. Foods containing GMO’s do not have to label it, and GMO soy may be hidden in foods, like broths, flavorings, cereals, stuffing’s and some oil based vitamin supplements (mostly processed foods).
If you are trying to eat a plant based diet that includes beans, whole grains, lots of vegetables, some fruit, heart healthy fats and lean proteins, then adding in whole soy foods is probably beneficial and there do seem to be some real health pluses. A note of caution, consuming more than 4-5 servings of soy foods a day can negatively affect the thyroid in people with low thyroid function. Thyroid medication should be taken several hours away from a soy containing food.
Bottom Line: Soy is safe and probably beneficial. Include up to 3 servings of whole soy food a day as part of a diet rich in vegetables, whole grains, fruits, heart healthy fats and some lean protein.
A recent survey showed that some Americans thought chocolate milk came from brown cows! I guess that can (kinda) make sense, although I’ve never seen a strawberry cow......?