Is Soy Bad For You?

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Soy is a vegetable included in the family of peas or legumes. A lot of studies claim that it could help menopausal women by relieving the symptoms they experience in menopausal stage specially hot flashes. Studies state that it contains isoflavones that once ingested by women imitates the actions of estrogen in the body and therefore alleviating some menopausal symptoms. In a large-scale study on soy, done by the experts from the University of Delaware, it was presented that soy may help fight hot flashes in menopause.

Numerous studies have stated the benefits of this food item such as it has low saturated fats; it is a good source of antioxidants; high in protein; cholesterol free; and aids in menopausal symptoms. Despite these researches, several claims indicate the opposite and specified that soy have actually bad effects on the body. Some of these studies state that it can cause breast cancer, can bring harm to an infant’s development and is actually a poison to the thyroid.

Soy comes in various types, which would bring health benefits and bad effects depends on the type of product you eat. This section will let you know the difference between these soy varieties and which of them should be avoided or preferred.

Fermented and Non-fermented Soy

There are two kinds of soy that you can find in the market: fermented soy, which is organic and freshly made out of the whole and organic soy; and non-fermented, which are found in genetically modified products that include other additives aside from whole soy.

Non-fermented Soy

Non-fermented types (genetically modified soy products) are said to have negative effects in the body. They contain phytic acid that blocks the absorption of certain minerals such as Copper, Zinc, Calcium and Iron in the digestive tract. Non-fermented ones also contain trypsin inhibitor that reduces the body’s ability to digest protein, which could depress children’s growth. Unfermented soy is usually found in genetically engineered soy foods such as ice cream, oil, cheese and burgers that could bring unwanted effects on health therefore should be removed from your grocery list

Fermented Soy

Asian cultures have only used soy as a food after learning how to ferment it. The process of fermentation removes trypsin inhibitors that block the absorption of nutrients found on soy. Additionally, fermentation adds nutrients and good bacteria to soy. Fermented soy is said to reduce the risk of cancer, promote healthy bones, be good for the heart and reduce menopausal symptoms. The Okinawans, who are the longest living race, have been including soy in their diet for 5 millennia. They consume whole and organic fermented soy such as natto, miso, tempeh, tofu and fermented soy milk, which they said one to two servings of this kind of food is good for health.

So Which Soy to take?

Now that you have a much clearer view of the difference between fermented soy and non-fermented soy, you might have now realized that it is always wiser to always choose fermented soy, as non-fermented soy is usually found in processed products that could lead to harmful effects in health. Most of the fermented soy food could be found in Asian cuisine. Examples of soy products are Doenjang (Korean soybean paste), Doubanjiang (Chinese soy paste), pickled tofu, soy sauce, stinky tofu, Tauco (Indonesian yellow soybean paste), and Chagem pomba (Indian curry made from soybean).

Positive and Negative effects of Soy

Is soy bad for you? There is a huge controversy about the use of soy. As others claim its health benefits while some say it could bring harm. That’s why it is vital to be careful and choosy in preferring the kind included in the diet. Always look at the contents and be sure you’re not consuming processed soy products. It is always better to prefer fermented soy than non-fermented ones to avoid unwanted effects on the body. The amount of consumption should be moderate too. As any products consumed in excessive amounts could lead to health risks. There are good and bad effects of this food item that some studies suggest, which we should be aware of in order to elude the unnecessary effects it could bring in our health.

Improvement in Menopausal Symptoms

Proven claims have showed that soy decreases menopausal symptoms. This is due to isoflavones that imitate estrogen once consumed by the body. The low levels of estrogen in menopausal women result in menopausal symptoms, therefore consumption of soy alleviates the episodes of symptoms. Women who take at least 50 mg of soy isoflavones showed lesser occurrences of hot flashes than women on placebo.

Effect Against Breast Cancer

There is insufficient evidence if it has protective or harmful effects on breast cancer risk. Some studies show that there is no relationship between soy consumption and the prevention of breast cancer. However, some studies have shown significant results that women who consume soy in their adolescent years have lesser risks of breast cancer.

Effect in Heart

A current American Heart Association Science Advisory paper reviewed 22 clinical studies on soy, and later on, found out that it has no proven benefits for the heart. The study of AHA involved isolation of isoflavones (a component that lowers bad cholesterol), which showed only 3% of the active component is consumed in the average daily consumption of soy by individuals. This percentage has no significant effects on the heart, as well as for the lowering of cholesterol or decreasing blood pressure.

Effect in Bones

Studies showed that soy could prevent bone loss, osteoporosis and could help in the prevention of bone degradation of spine. A two-year study has shown this significant result from women who drink 17 ounces of soymilk daily, where it slowed down bone degradation in post-menopausal women. However, how soy and its isoflavones produce that effect in bones is still unclear.

Effects in the Thyroid

Excessive consumption of this food item can disturb thyroid function because isoflavones in it block the signals that the thyroid sends to the cells for its proper function. This event could result in goiter (enlargement of the thyroid) in people with iodine deficiency, as well as in infants who are fed with a soy-flour formula that is not iodine fortified.

Effect in Reproductive Health

Animals that eat excessive amounts of soy have reduced probabilities of fertility or become infertile. However, in 2004 research conducted in adult and infant populations showed that consumption of soy-based infant formulas did not negatively affect development or reproduction.


Gita is the founder of My Menopause Journey. Since 2014, she has been supporting midlife women by sharing hard-earned learnings from her own experience. To advance her knowledge, Gita puts a lot of her time and effort into understanding the broad spectrum of women’s health. She immerses in extensive research about the physical, mental and emotional aspects of menopause. Gita believes in the life-changing power of healthy, holistic living — this is where she anchors her message to all women. Learn more about her marvelous mission in About us - My Menopause Journey.

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