Soy protein is the primary protein found in soy products, such as tofu, tempeh, soy milk, and other soy-based dairy and meat alternatives.
It can also be found in the form of soy protein powder, which you can use to supplement a workout routine or add more protein to your diet in general.
For people following a plant-based diet or who don’t eat dairy, soy foods often serve as a major source of protein, as well as vitamins and minerals.
Although some people believe soy to be a nutrient powerhouse, others question whether it poses unwanted side effects.
This article examines the evidence to determine whether soy protein is a good addition to your diet, then offers a few ideas for how to enjoy it.
Soy comes in a wide variety of forms, all of which have varying nutrients and health effects.
On one end of the spectrum are whole or minimally processed soy foods, such as tofu, tempeh, and whole soybeans — also called edamame.
Soy milk is slightly more processed. To make soy milk, soybeans are cooked in water, pulverized, and pressed to remove the solids and fiber. Manufacturers may add other ingredients and nutrients.
On the most highly processed end of the spectrum, you’ll find soy protein powder or soy protein isolate. They’re often used as an ingredient in certain packaged foods like protein bars.
Soy protein isolate powder is made from defatted soybean flakes that have been washed in either alcohol or water to remove the sugars and fiber. They’re then dehydrated and powdered.
Overall, soy is a good source of protein and fiber, as well as vitamins and minerals like calcium, iron, magnesium, and zinc. It contains some unsaturated fat and is free of cholesterol.
This chart shows the nutrition facts for one serving of a few types of soy foods (1, 2, 3):
As you can see, the fat, fiber, carb, and mineral counts of soy foods fall into a wide range.
Soy protein isolate packs the most protein per serving, which makes sense because it’s processed to be a concentrated source of this nutrient.
One of the most common criticisms of plant proteins is that they don’t contain all of the essential amino acids, which your body needs to make protein. However, this is a misconception — as is the idea that plant proteins are inferior to animal proteins.
All plants contain all nine essential amino acids, but some only offer very limited amounts. For instance, lysine only occurs in small amounts in most grains and cereals (4).
This just means that you should include other sources of lysine in your diet, such as soy, so that your body can make all the protein it needs. All you need to do is enjoy a diverse diet, which is good for your health in general.
Soy foods not only contain all nine essential amino acids but also offer ample amounts of each, making soy similar to animal proteins in this way (5).
Soy may aid heart health, cancer risk, and blood sugar levels. These benefits are largely attributed to soy’s health-promoting compounds like phytosterol, saponins, lecithin, phytic acid, and isoflavones, in addition to its nutrition profile (6).
Commercial soymilk, soy flour and soy cheese should also be avoided. So if you are ingesting “overcooked” commercial soy, yes it will contribute to cancer cells being formed in the body. The other soy is cold water washed and very few companies use this method as it is more expensive but leaves the nutrients intact.
May protect heart health
Soy foods appear to have positive effects on heart health (7).
In one review of 35 studies, soy intake lowered LDL (bad) cholesterol and raised HDL (good) cholesterol (8).
This matters because high levels of blood fats like LDL and triglycerides are associated with a higher risk of heart disease, stroke, and heart attack (9).
Women who consume soy foods over a lifetime have fewer symptoms of menopause, such as hot flashes, according to studies published in Lancet (1997) and Obstetrics and Gynecology (1998). In preliminary clinical studies, soy increased or maintained bone density in postmenopausal women and alleviated mood swings, reduced hot flashes, sleep problems, etc.
I picked up a December copy of the Chatelaine magazine in a waiting room the other day. I saw an article on soy and decided to read it. This article said it was going to dispel the rumours around soy. It started off saying, ”Soy. One minute it’s the answer to all our health problems, the next it’s a hidden hazard”. The author, Anna Cipollone, pored over the latest research to clear up the controversy. Unfortunately not all the research was accurate. In this article, I’ll discuss Anna’s findings and offer a quality control soy checklist to ensure you are purchasing the best quality product.
The part she had right here was to avoid heavily processed soy foods. What she didn’t find in her research was that not all soy foods are created equal. Processing makes a big difference; whenever you cook a food you de-nature it and make it into something different. Depending on the processing, some soy products have lots of isoflavones, some none at all. Isoflavones are the phytoestrogen compounds that are considered antioxidants and prevent cancer.
Soy has been proven to reduce high cholesterol levels – often around 10 % – in many studies. Controlled clinical trials have found that 25 grams of soy in the diet daily can reduce levels of LDL cholesterol while maintaining HDL cholesterol. It also prevents plaque formation, slows growth of existing plaque, reduces risk of blood clot formation, lowers blood pressure, and increases elasticity of vessels. In November 2000, the American Heart Association recommended that soy protein be added to our daily diets to help reduce cholesterol and as part of a heart-healthy lifestyle.
I know companies that are very picky about their soy protein. They will not use any ingredients that are genetically engineered, though it would cost them less to do so. Call the company to verify if you do not see “non GMO” listed on the label. Usually it will be labelled though.
Is Soy Dangerous? | Neal Barnard, MD
FAQ
Why you shouldn’t eat soy everyday?
Is soy bad for gut health?
Are products with soy bad for you?
Is isolated soy protein bad for you?
Is soy bad for women?
No, soy is not bad for women. As discussed above, it may protect against breast cancer and be helpful for women with PCOS. But it may have more benefits for women beyond this, particularly after menopause. The beneficial compounds in soy may help slow bone loss, improve muscle function, and help women with weight loss after menopause.
What are the bad effects of soy?
There are no negative effects of consuming soy, unless it is genetically modified. On the other hand, children under five years of age should avoid soy and its derivatives. There products contain isoflavores which are phytochemicals with hormonal-like effects.
Is soy safe?
We now have good research debunking the common myths surrounding soy. Not only is it safe, it may also have potential health benefits. For example, soy may lower cholesterol levels, and it appears to be beneficial in preventing or treating certain kinds of cancer.
Is soy bad for men?
Dawn Jackson Blatner, RDN, a Chicago-based dietitian, says that while whole soy contains natural plant estrogens, they are much weaker than actual human hormones, and shouldn’t cause you to worry. There has also been concern that the isoflavones in soy can affect men’s hormonal levels, lowering testosterone and raising estrogen levels.