Soy has been a hotly debated topic for quite some time.
Some articles will praise the benefits of the legume, while others warn not to touch soy with a ten-foot pole. Having so much research at our fingertips is amazingly helpful at times, but it can be overwhelming and confusing when the research from various credible-looking sources seems to contradict one another.
So, for the million-dollar question, should we eat soy or not? Is it beneficial or harmful?
The short answer is yes, you should eat soy. It is beneficial for you.
Clearly, we’re not going to leave it at that. We’re not here to give you black and white guidelines about what to eat and what not to. We want to explain why soy is good for you and explore why it has gotten a bad rap out there.
So, for the long answer….
Benefits of Soy
- Soy is a great source of protein that is naturally cholesterol-free and low in saturated fat. This sets it apart from animal proteins, which tend to be high in saturated fat. Since high intakes of saturated fat have been linked to cardiovascular disease, replacing animal proteins with soy proteins reduces one’s risk of heart disease.
- Compared to other beans, soybeans contain a much smaller percentage of carbohydrates and a larger percentage of protein and fat. This is especially helpful for diabetics. A ½ cup of shelled edamame (green soybeans) contains 120 calories, 11 grams protein, 2.5 grams fat, 13 grams carbohydrates, and 9 grams of fiber.
- The protein in soy is a complete protein, which is often not the case with plant-based proteins. This means it contains all 9 essential amino acids that the body cannot make on its own. This is a great source of protein for vegetarians who may struggle to get all the amino acids at one sitting! 20 amino acids=1 protein gram. Therefore, by getting the 9 essential amino acids within our food, therefore, our bodies can form a complete protein.your body makes the other 11 amino acids.
- Soy foods such as edamame (green soybeans), black soybeans, soy nuts, soy flour and tempeh are a good source of fiber. Increased fiber intake has been proven to have gastrointestinal benefits, can reduce cholesterol, and lower one’s risk of developing heart conditions.
- Soy foods contain polyunsaturated fats- your omega 3s. Consumption of omega 3s has been linked to improved cardiovascular health.
- Soy foods are rich in vitamins and minerals such iron, zinc, potassium, calcium and B-vitamins. They also contain antioxidants, which have been proven to impart numerous health benefits.
- Soy contains isoflavones, which have been associated with reduced bone loss in postmenopausal women and prevention against certain cancers.
It is important to note that the above benefits are associated with whole soy products such as soy beans, tofu, tempeh, soy nuts, and soy flour and NOT with derivatives such as soy protein isolates or soy isoflavone supplements.
So, why all the negative soy talk?
There have been research studies that concluded that soy is a dangerous food to eat. Evaluating a research article is extremely difficult because there are so many factors that play into each experiment.
Was the research conducted on animals or humans? What type of soy food is being studied? Were the participants of a certain ethnicity? What else were the subjects eating or doing throughout the study? Could there be other confounding factors?
Clearly, relying on one isolated study is not enough to determine risk factors. Researchers have found that animals metabolize soy differently than humans do. Many of the studies linking soy to negative effects have been conducted with animals. They have also found that consumption of whole soy products is associated with health benefits, but the benefits to soy derivatives, such as soy isoflavone supplements, is less known.
One of the biggest scares about soy is its association with cancer. According to the American Cancer Society, consumption of soy may actually protect against hormone-related cancers such as breast, prostate, or endometrium cancers.
The fear is based on the fact that soy contains isoflavones which have estrogen-like properties. However, it is because of these isoflavones that soy can actually protect against cancer! The estrogen in the body is linked to feeding the cancer in the body, so the isoflavones can actually block their effects by binding to the estrogen receptors in the body.
Think of the estrogen like a key which binds to the estrogen receptor, the keyhole, and causes negative effects. Now imagine a very similar key, the soy isoflavones, comes and fits into the same receptor, leaving the harmful estrogen without a place to bind and impart negative effects.
Another concern regarding soy is its potential to cause feminization in men by increasing estrogen levels and decreasing testosterone levels. There have been two studies published that led to this concern. Taking a deeper look into the studies reveals that the amount of soy isoflavones consumed by these men was 360 mg, a number 9-fold greater than the average soy consumption in older Japanese men, who have been reported in the studies noted below to consume more soy than the average American!
So yes, in excessive amounts, soy may have negative effects on male hormones. However, in more moderate consumption, such as 150 mg soy isoflavones per day, soy does not show to have any negative impacts on male hormone levels.
Much research has been conducted on soy and various health conditions and disease states. If someone has a specific health condition, they should talk to their doctor or find research-based articles from reputable sources that discuss how soy can impact their specific condition.
In conclusion, navigating through the soy talk is quite a task. The main takeaway is that moderate consumption of whole soy products is completely safe and may even have beneficial effects for the average person.
So please, enjoy that tofu you were planning on eating for dinner tonight!
Malky Shafran, Dietetic Intern
University of Northern Colorado Distance Dietetic Internship Program
Michele Wroblewski, RDN
Caruso Physical Therapy and Nutrition, LLC
1278 Yardville Allentown Rd. Suite 3
Allentown, NJ 08501