You see this ingredient in so many vegan products, but what is it? And should you be worried about eating it? Here is the scoop on Soy Protein Isolate and why it’s in so many vegan or plant-based foods.
The Impossible Burger has it. So, too, do vegan protein bars, other fake meats, and some granolas. In fact, suffice to say that if you’re eating vegan food, you’re probably consuming soy protein isolate. Yet while you’re familiar with soy and protein and know they’re healthy, the isolate part has you confused. No more, as experts weigh in below and explain what this foreign-sounding ingredient is–and why it shouldn’t actually be a huge worry.
Defining what is soy protein isolate?
True to its name, soy protein isolate originates from soy, specifically defatted and dehulled soybeans, according to the Journal of Nutrition. By soaking the soybeans, protein can essentially be isolated out and dehydrated. As a result, that soy protein isolate becomes an ultra-rich source of protein, its content about 90 percent protein, says Nanci S. Guest, Ph.D., R.D., C.S.C.S., plant-based dietitian and nutrition scientist at the University of Toronto in Ontario.
Soy protein isolate is then added to foods, which not only boosts the protein content but also does so without adding additional fat or calories. It’s not unlike how manufacturers use whey protein isolate with one obvious difference. “Soy protein isolate is from plants, and whey is one of two proteins from dairy,” Guest says.
The pros and cons of soy protein isolate
Throughout the years, soy has had to fight to earn its justly deserved spot in the health food world, people often harboring an erroneous belief that isoflavones, also called phytoestrogens, in soy can increase your risk of breast or prostate (or other hormonal) cancer. Fortunately, numerous studies now exist to show the benefits of eating a moderate amount of whole soy foods like soybeans and edamame, and even minimally processed soy foods like tofu and soy milk. “These foods help reduce the risk of cancer, especially breast and hormone-related cancers, and recurrence of cancer,” says Susan Levin, M.S., R.D., C.S.S.D., director of nutrition education for the Physicians Committee for Responsible Medicine.
So what’s the worry with soy protein isolate? There’s some concern that like cow’s milk, soy protein isolate may increase insulin-like growth factors such as IGF-1. “Once soy protein isolate is extracted from food, it may promote cancer and cancer growth,” Levin says, citing a study in Nutrition and Cancer that recommended men with early-stage prostate cancer “not to exceed dietary protein recommendations.”
Others, however, say otherwise. “There’s zero evidence that soy protein isolate acts differently than soy food,” Guest says. In fact, soy protein isolate may actually have some health benefits.
Soy protein isolate may be beneficial in small amounts
According to the National Cancer Institute (NCI), soy protein…