Is soy good for your heart? The Food and Drug Administration says it’s not so clear-cut, and proposed Monday to revoke the claim that soy protein can prevent heart disease.
That doesn’t mean soy is not good for your heart, or that it doesn’t have a range of other benefits, the FDA said.
And food makers could possibly make what’s known as a “qualified” claim — meaning there is some evidence that soy is good for your heart. Soybean oil may still carry a qualified claim.
But there’s just not enough evidence to say straight up that eating soy protein helps your heart, the agency said.
"Let's be clear this claim is about soy protein, not soy products broadly but soy protein and coronary heart disease," the FDA’s Susan Mayne told NBC News.
It's the first time the FDA has revoked a health claim.
Mayne said a review of all the recent studies showed conflicting evidence on whether soy protein directly lowers the risk of heart disease.
"That science is not as conclusive as you would hope for a health claim with regard to soy protein and coronary heart disease," added Mayne, who heads the agency’s food safety and nutrition center.
The American Heart Association regularly reviews the evidence that certain foods fight heart disease and decided in 2006 that there was not enough evidence that soy lowers cholesterol so much that it reduces heart disease risk.
The Heart Association also opposes allowing a "qualified" health claim, saying that just confuses people.
One worry is that people will simply add foods like soy to a standard American diet heavy in meat, processed carbs, sugar and unhealthy fats. “A lot of people have unrealistic expectations about these foods, thinking they’ll be protected from chronic diseases and health problems,” nutrition professor Penny Kris-Etherton of Pennsylvania State University says in a statement posted on the American Heart Association’s website.
“They may eat one or two of these nutrient-dense foods on top of a poor diet.”
The evidence suggests that it’s not so much adding soy to the diet that lowers cholesterol and reduces heart disease risk, but eating it instead of more unhealthy foods.
One study used to allow heart claims about soy looked at nearly 5,000 men and women in Japan, where those who ate the most soy had the lowest cholesterol levels.
A 1995 meta-analysis — a catchall study putting together data from many other studies — found that people who ate 50 grams of soy protein a day instead of meat, milk or cheese reduced levels of “bad” LDL cholesterol by almost 13 percent.
But other studies have not shown such a definitive cause and effect. “Our review of that evidence has led us to conclude that the relationship between soy protein and heart disease does not meet the rigorous standard for an FDA-authorized health claim,” the FDA said.
The FDA just allowed soy oil makers to claim their product is heart-healthy, and Monday’s proposed action doesn’t affect that. As with canola and olive oil, soy oil producers can use a label saying that 1.5 tablespoons of soybean oil a day may reduce the risk of coronary heart disease when it replaces saturated fat.
"No one is saying that soy is bad," said Dr. Steve Nissen, a cardiologist at the Cleveland Clinic.
"Can soy be part of a healthy diet? Of course it can. Just don't expect any magical benefits."
There’s much evidence showing soy foods can help people’s health — including prevention of cancer.
Soybeans are high in fiber, as well as compounds called isoflavones, which include daidzein and genistein. Genistein can interfere with cell growth and proliferation and that in turn may slow tumors.
“Even though soy protein has little direct effect on cholesterol, soy foods are good for the heart and blood vessels because they usually replace less healthful choices, like red meat, and because they deliver plenty of polyunsaturated fat, fiber, vitamins, and minerals, and are low in saturated fat,” the Harvard School of Public Health says on its website.
The FDA has been examining the soy food issue for more than a decade. It’s been under pressure to revoke the claim from some groups, including the Weston A. Price Foundation, which advocates for raw milk and butter and opposes vaccinating children.
In 2016, the FDA denied a petition from the Weston A. Price Foundation seeking to revoke the health claim for soy.
“The petition failed to address the significant number of intervention studies that do show a reduced risk of coronary heart disease — a critical deficiency,” the FDA said in its denial.
Just under a third — 31 percent of Americans — eat soyfoods or soy beverages once a week or more, according to the Soyfoods Association of North America.
The group says 45 percent seek out products specifically because they contain soy.
The FDA says it’s still OK to do that.
“For consumers who have questions about eating soy products, we recommend they continue to follow advice from the 2015-2020 Dietary Guidelines, which state that a healthy eating pattern can include soy beverages and a variety of protein foods, including soy products,” the FDA said.