Soy: beneficial or not?
On the one hand, soy is rich in nutrients and its consumption, in controlled quantities , appears to be linked to health benefits, such as lowering blood sugar levels , improved heart health , reduced symptoms of menopause . However, the wholesomeness of soy-rich diets has long been debated. For example, due to concerns about the risk of breast cancer , or the assumption that frequently eating soy or soy-based foods may impair thyroid functionor have feminizing effects in men, just to name a few.
Nutritional profile of soy
| Soya beans | Tofu | Tempeh | Soy beans | Soy yogurt | Soya milk | |
|---|---|---|---|---|---|---|
| Calories | 172 | 144 | 195 | 121 | 94 | 43 |
| Protein | 18 grams | 17 grams | 20 grams | 12 grams | 4 grams | 3 grams |
| Fats | 9 grams | 9 grams | 11 grams | 5 grams | 2 grams | 1 gram |
| Carbohydrates | 8 grams | 3 grams | 8 grams | 9 grams | 16 grams | 5 grams |
| Sugars | 3 grams | – | – | 2 grams | 1 gram | 4 grams |
| Fiber | 6 grams | 2 grams | – | 5 grams | less than 1 gram | less than 1 gram |
| Calcium – % of Daily Value (DV) | 8% | 53% | 7% | 5% | 9% | 9% |
| Iron – % of DV | 29% | 15% | 12% | 13% | 6% | 2% |
| Magnesium -% of DV | 20% | 14% | 18% | 15% | 10% | 4% |
| Phosphorus -% of DV | 20% | 15% | 20% | 14% | 3% | 3% |
| Potassium -% of DV | 11% | 5% | 9% | 9% | 1% | 3% |
| Zinc -% of DV | 10% | 14% | 14% | 12% | 3% | 2% |
| Copper – % of DV | 45% | 42% | 60% | 38% | 8% | 18% |
| Manganese -% of DV | 36% | 51% | 56% | 45% | – | – |
| Selenium – % of DV | 13% | 32% | 0% | 1% | 24% | 4% |
| Thiamine – % of DV | 13% | 13% | 5% | 17% | 3% | 2% |
| Riboflavin – % of DV | 22% | 8% | 27% | 12% | 2% | 14% |
| Vitamin B6 – % of DV | 14% | 5% | 12% | 6% | 1% | 2% |
| Folate – % of DV | 14% | 7% | 5% | 78% | 2% | 2% |
Soybeans are naturally high in protein and contain all the essential amino acids the body needs. They are also high in vegetable fats, fiber , and several important vitamins , minerals , and beneficial plant compounds. Soybeans are also a natural source of polyphenols , a type of antioxidant that can help protect the body from cell damage and conditions like heart disease .
Soybeans are particularly high in isoflavones , a subclass of polyphenols referred to as phytoestrogens due to their ability to attach to and activate estrogen receptors in the body. Soy isoflavones are thought to be one of the main reasons behind the many purported health benefits of soy foods . Due to their similar structure, soy isoflavones are often believed to mimic the hormone estrogen . However, research suggests that soy isoflavones differ from estrogen in many ways, each of which has unique effects on the human body.
Soy: the health benefits
Soybeans have several health benefits.
- Reduces cholesterol . Several studies suggest that diets high in soy foods may help lower LDL (bad) cholesterol and raise HDL (good) cholesterol . An average intake of 25 grams of soy protein per day can help reduce total and LDL (bad) cholesterol levels by approximately 3%. Additionally, minimally processed soy foods , such as soybeans, tofu, tempeh and edamame , appear to improve cholesterol levels more than processed soy products and supplements .
- It can help protect heart health. Diets high in legumes , including soy, may help reduce the risk of heart disease. It appears that soy isoflavones may help reduce inflammation in blood vessels and improve their elasticity, two factors thought to protect against heart disease.
- It can lower blood pressure . Soybeans and foods made from them are generally high in arginine , an amino acid thought to help regulate blood pressure levels .
- Reduces blood sugar levels . The isoflavones in soy may help reduce blood sugar and insulin levels in menopausal women. Soy isoflavones may also help reduce insulin resistance , a condition in which cells no longer respond normally to insulin. Over time, insulin resistance can result in high blood sugar levels and lead to type 2 diabetes .
- May be beneficial in metabolic syndrome . Metabolic syndrome refers to a group of conditions, including high blood sugar , cholesterol levels, blood pressure, and belly fat , that together tend to increase a person ‘s risk for type 2 diabetes, heart disease, and stroke .
- It can improve fertility. Some research suggests that women who eat diets rich in soy may benefit from improved fertility. However, men may not experience the same fertility-boosting benefits.
- It can reduce the symptoms of menopause. Soy is rich in isoflavones, a class of compounds also referred to as phytoestrogens or plant estrogens, due to their ability to bind to estrogen receptors in the body. During menopause, a woman’s estrogen levels naturally decrease, resulting in unpleasant symptoms, such as fatigue, vaginal dryness , and hot flashes. By binding to estrogen receptors in the body, soy isoflavones are believed to help reduce the severity of these symptoms.
- It can improve bone health . The low estrogen levels experienced during menopause can cause calcium to leak out of the bones. The resulting bone loss can lead postmenopausal women to develop weak and brittle bones, a condition known as osteoporosis. Soy isoflavone intake may reduce bone loss and improve markers of bone health in menopausal women.
Downsides
Soybeans and foods derived from them are often a cause for concern. There has been much debate about the benefits of taking them. The reasons range on several fronts: from estrogen-mimicking effects (soy isoflavones have been shown to have weaker and slightly different effects than estrogen) to cancer risk . Opinions differ on soy isoflavones which may increase the risk of breast or endometrial cancer . However, most studies have found no negative effects. In some cases, they may even offer some protection against some types of cancer. Thyroid function tooreduced, as it has long been thought, caused by some compounds found in soy, has no scientific evidence: several studies have found minimal or no negative effects.
Downsides:
- GMOs . Soybeans are often genetically modified (GMO). GMO soybeans may contain fewer nutrients and more herbicide residues than conventional or organic soybeans.
- Antinutrients. Soybeans contain compounds that can reduce the body’s ability to absorb the vitamins and minerals they contain. Soaking, sprouting, fermenting, and cooking are ways to reduce these antinutrient levels in soybeans.
- Digestive problems . The antinutrients in soy can reduce the barrier function of the intestine , possibly leading to inflammation and digestive problems.
Soy-based foods: pros and cons
It’s worth noting that not all soy foods are equally nutritious or beneficial. In general, the less a soy-based food is processed, the more vitamins, minerals and beneficial compounds it can contain. More processed soy-based foods contain more salt , sugar, fat and additives such as: soy-based protein powders, soy-based burgers and patties (often a substitute for meat in vegan and vegetarian diets ), energy drinks and sweetened soy and yogurt drinks .
In this sense, prefer slightly processed or fermented soy-based foods, such as:
- soya beans,
- tofu,
- tempeh,
- edamame,
- unsweetened soy milk and yogurt,
- miso,
- natto,
- soy sauce.
