by Jessie Funchion, MS, RD, LDN
As of now, the research tells us that yes, the consumption of soy foods is associated with health benefits, including but not limited to:
· reduced risk of breast cancer
· risk of recurrence of breast cancer
· decreased LDL, total cholesterol and triglycerides
· reduced blood pressure
· decreased risk of heart disease
According to the United Soybean Board, 81% of consumers view soy as healthy, which means about 19%, or 1 in 5 people view soy as unhealthy or neutral.
What’s in soy?
Soy is a higher-fat legume that contains about 27% carbohydrate, 33% protein and 40% fat. It is a complete protein and is easily digested.
Doesn’t soy contain phytoestrogens?
Soy contains both phytoestrogens and anti-phytoestrogens. What this means, is that soy contains a chemical structure that looks a lot like human estrogen. This fact has led people to fear that the consumption of soy can affect estrogen levels in humans, thus making them at higher risk for estrogen sensitive diseases like breast cancer. We now know that this is not true. These compounds sometimes act like estrogen in the body, but other times they exhibit effects that are opposite to estrogen.
From the American Institute for Cancer research Website:
Because soy contains estrogen-like compounds, there was fear that soy may raise risk of hormone-related cancers. Evidence shows this is not true.
A good comparison is the sterols in animal vs. plant foods. Cholesterol in animal foods is very chemically similar to phytosterols in plant foods, but as we all know, they exhibit very different effects in the body. Just because a molecule is similar, does not mean it will produce the same results in the body.
How much soy do I need to reap the health benefits?
Dr. Messina, recommends 2-4 servings per day or about 25g or soy protein a day, while the American Institute for Cancer Research recommends a moderate amount of soy per day, which is 1-2 servings. 1 serving = 1 cup soy milk, ½ cup edamame, or 1/3 cup tofu.
How about soy and thyroid health?
Soy can interfere with absorption of thyroid medication (as does calcium, iron, dairy, etc.), so the recommendation is to separate levothyroxine from soy by about 4 hours. Whether soy itself can interfere with thyroid function, or even contribute to hypothyroidism, is a hotly debated topic. Dr. Messina’s research purports that soy is not currently contraindicated in the hypothyroid patient, nor should it impact the thyroid health of healthy individuals. I would love to see any articles for or against soy and thyroid health!
The American Institute for Cancer Research (AICR) website is a good resource to provide you with the latest research.
Practical ways to increase soy in diet:
· Try unsweetened soy milk instead of cow’s milk or almond milk
· Snack on edamame or add a handful to salads
· Try tofu scramble instead of scrambled eggs
Resources:
1) To Soy or Not to Soy: Effects of Soybeans on Breast Cancer, Menopause and Heart Disease
