If you’ve been thinking about switching to a more plant-based diet, for environmental or health reasons, you’ll notice that many meals contain some type of soy. From tofu and tempeh to soy protein isolate found in mock meat, there are many different forms of soy available.
Despite soy’s ubiquity, there are many rumors swirling about whether or not it’s good for you. To get answers, Fortune spoke to experts: here’s what you need to know.
Soy products are derived from the soybean plant, a member of the legume family. You may recognize the seeds as the popular food Edamame. The US is the largest soybean producer in the world, according to the Department of Agriculture.
It is perhaps one of the most important crops, providing protein for animals and people, and also being processed into biofuel, vegetable oil and other food products.
Some common soy food products include: tofu, edamame, tempeh, miso, soy milk, soy sauce, soy protein isolate, soy oil and textured vegetable protein.
The concerns about soy mainly stem from two studies from 1987 and 1998, says dietitian Lauren McNeill, who specializes in plant-based nutrition. Researchers examined how raw soybeans consumed by mice affected their hormone levels and health outcomes. They found that soy increased the risk of cancer in the mice and stimulated breast growth.
Soy contains phytoestrogens, meaning it has a similar chemical structure to estrogen and can potentially mimic and increase estrogen activity in the body. That caused people to worry that phytoestrogens, like those in soy, might put you at increased risk for breast cancer because estrogen activity can act as a catalyst for cancer growth.
Other concerns about soy included how it could potentially inhibit thyroid function, based on animal and test-tube studies.
But those studies are fundamentally flawed, McNeill says.
“Soy is not inherently what mice eat in general… it’s not good research to translate this to humans,” says McNeill. Fortune. There is actually some evidence pointing to the general benefits of soy for human health.
A number of more recent studies and reviews of research have debunked concerns that soy is harmful to your health. Research has shown that soy has no significant influence on thyroid function; this relationship is still being investigated. A 2010 study also tested the impact soy had on male reproductive hormones. They found that soy did not affect testosterone or other sex hormones in men.
“We now have very clear human data showing that there is no association between soy consumption and an increase in cancer risk and an increase in cancer recurrence,” said Dr. Neil Iyengar, medical breast oncologist at Memorial Sloan Kettering New York Cancer Center.
“There are many benefits to adding soy to products [your] diet,” says McNeill.
In fact, several studies have shown that eating soy not only helps lower cancer risk, but can also broadly improve health outcomes.
Soy products like tofu, edamame and tempeh are packed with fiber, protein, vitamins and minerals, with the added bonus of being plant-based, which Iyengar says is beneficial to his patients because of the overall health and longevity benefits that come from them. a plant-forward diet.
“The good thing about soy is that it is such a rich source of nutrients… I certainly wouldn’t tell people to avoid soy,” he says. “In fact, I would tell people to use soy as part of a healthy, cancer-protective diet.”
A 2009 study of 5,042 female breast cancer survivors in China – women aged 20 to 75 with diagnoses between March 2002 and April 2006 – found that those with diets higher in soy had a significantly lower risk of death and cancer recurrence. Meanwhile, soy consumption for men also appears to help lower the risk of prostate cancer, according to a 2018 study.
Meanwhile, a 2019 review explains that phytoestrogens, found in soy, have been linked to a number of benefits, including cardiovascular and cognitive function, skin health, aiding weight loss and minimizing symptoms of menopause.
Other benefits of soy include:
Some forms of soy are more processed than others, such as soy protein isolate or textured vegetable protein – common in protein powders and vegan meat alternatives – and soy oil, which is found in many processed foods and used as a cooking oil in many restaurants. It is best to consume minimally processed soy foods to maximize the benefits of protein, fiber and other nutrients in soy.
Here are some soy products you can include in your diet:
McNeill’s favorite way to prepare tofu is to toss it in olive oil, garlic powder, salt, paprika and nutritional yeast, then pop it in the air fryer or oven and add to stir-fries, salads and wraps. She also loves steaming edamame and seasoning it with salt.
“The less processing, the better,” says Iyengar.
Iyengar recommends one to two servings of soy per day to see the health benefits observed in numerous studies. However, this recommendation does not mean that it is bad to consume more than that. He says that because foods like tofu and edamame are so high in protein and fiber, soy probably fills you up quite easily — and if you eat more than one to two servings, it could mean you run out of room for other foods that are rich in protein. is of nutrients.
“You can eat soy every day if you want,” says Iyengar.
