Soy is arguably one of the most controversial topics of nutrition. On the one hand, it is rich in nutrients, and diets containing it appear to be associated with health benefits, such as:
- Low blood sugar levels
- Improve heart health
- Reduce menopause symptoms
- And possibly even a reduced risk of some types of cancer
However, on the other hand, some people are concerned about the health of soy-rich diets.
For example, some fear that eating a lot of soy may increase the risk of breast cancer, impair thyroid function, or have female effects in men, to name a few.
This article reviews the latest scientific evidence to determine whether eating soy is likely to have positive or negative effects on your health.
Why are some people worried about soybeans?
Soybeans and foods derived from it have been part of the human diet for centuries. However, some people are concerned about including soy in their diet due to the following areas of concern:
1- Because of the estrogen-mimicking effects.
Soy isoflavones are often thought to mimic the female reproductive hormone estrogen.
Although similar in structure to this hormone, soy isoflavones have weaker and slightly different effects than estrogen (s).
2- Because of the fear of cancer risk.
Some people believe that soy isoflavones might increase the risk of developing breast or endometrial cancer. However, most studies do not find any negative effect.
In some cases, it may offer some protection against some types of cancer (s, s, s, s).
3- Because of the function of the thyroid gland.
Test-tube and animal studies suggest that some compounds in soybeans may decrease thyroid function.
However, human studies have found few or no negative effects, especially in humans with healthy thyroid function (s, s, s).
4- Because of leaving traces of feminization in men.
Some are concerned that soy isoflavones might reduce production of the male hormone testosterone.
However, human studies have found a weak link between the two (s, s).
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5- Because of the misconception about children.
Some fear that soy formula may negatively affect the brain, sex, thyroid, or immune development.
However, studies usually fail to note any long-term negative effects of soy formula in healthy, full-term babies (s, s, s).
6- Because of genetic modification.
Soybeans are often genetically modified (GMO). Genetically modified soybeans may contain fewer nutrients and more herbicide residues than conventional or organic soybeans.
More research is needed on the long-term health effects of genetically modified soybeans (s, s).
7- Because of anti-nutrients.
Soy contains compounds that may reduce the body's ability to absorb the vitamins and minerals it contains.
Soaking, growing, fermenting, and cooking are ways to reduce the levels of antinutrients in soybeans (s, s, s, s).
8- May cause digestive problems.
Animal studies suggest that antinutrients in soybeans may reduce intestinal barrier function, which can lead to inflammation and digestive problems.
However, more human studies are needed to confirm this (s, s, s).
Keep in mind that while these concerns are common, few are backed by sound science. Furthermore, when negative effects are observed, they often follow the consumption of very large amounts of soy.
For example, men who reported experiencing feminizing effects from eating soybeans in amounts up to 9 times greater than the average intake of men following a soy-rich diet.
Although it is possible, it would be difficult for most people to eat a lot of soy each day (s).
See: 22 Best Plant-Based Protein Foods
Are foods containing soy the same?
It is worth noting that not all soy foods are equally nutritious or beneficial. In general, the less processed a soy food is, the more vitamins, minerals, and beneficial compounds it may contain.
On the other hand, the more processed soy food, the more salt, sugar, fat, additives, and unnecessary fillers it is likely to contain.
This is why minimally processed soy foods, such as:
- Soybeans
- Tofu
- Tempeh
- Edamame
- Soy milks
- Yogurt
They're better than soy-based protein powders, mock meats, nutritious cuts, or sweetened soy milk and yogurt.
Slightly processed soy foods may also offer benefits beyond those associated with their nutrient content.
For example, they appear to be more effective at lowering blood sugar or cholesterol levels than foods or supplements that contain soy (s, s).
Additionally, fermented soy foods, such as:
- Soy sauce
- Tempeh
- Miso
- NATO
More useful than non-fermented soy products. This is because fermentation helps reduce some of the antinutrients naturally found in soy foods (s).
This can help improve your body's ability to absorb the nutrients in soybeans.
Cooking, sprouting, and soaking are additional preparation techniques that can help reduce the anti-nutrient content of soy foods and enhance their digestibility (s, s, s, s).