The U.S. Food and Drug Administration called into question Monday the authorized health claim that soy protein reduces heart disease risk.
"We are proposing a rule to revoke a health claim for soy protein and heart disease," said a statement from Susan Mayne, director of the FDA Center for Food Safety and Applied Nutrition. "For the first time, we have considered it necessary to propose a rule to revoke a health claim because numerous studies published since the claim was authorized in 1999 have presented inconsistent findings on the relationship between soy protein and heart disease."
For consumers, the FDA's move does not change the nature of soy or its potential role as a vegetarian alternative to animal protein, wrote Linda Van Horn, professor and chief of nutrition in the Department of Preventive Medicine at Northwestern University's Feinberg School of Medicine, in an email.
"Vegetarian diets can be nutritious and offer a way to lower LDL-cholesterol when saturated fat intake from meats or other animal sources are substituted with vegetable protein and especially when accompanied by poly-unsaturated fat sources," Van Horn said.
"Bottom line: the FDA decision does not condemn soy protein as a harmful ingredient when consumed within a healthy eating pattern," she wrote. "It simply acknowledges the scientific evidence indicating no special benefit independently as an agent to reduce risk of CVD," or cardiovascular disease.
Soy protein comes from soybeans, and some research suggests that a daily intake of soy protein may slightly lower "bad" LDL cholesterol, possibly leading to healthy-heart benefits.
"But we've since learned that not every way of lowering cholesterol has benefits, and some things that do lower cholesterol actually have shown harm, (and) what we know is that there was never any clinical trials ever that showed eating more soy improves heart health," said Dr. Karol Watson, a cardiologist and director of the UCLA Women's Cardiovascular Health Center.
Yet many Americans rely on high-quality protein like soy, said John Erdman, professor emeritus in the division of nutritional sciences at the University of Illinois at Urbana-Champaign and a scientific adviser to the Soy Nutrition Institute.
"If nothing else, it doesn't contain cholesterol, and it's not high in saturated fats, so if you're replacing meat or dairy with soy, you're automatically getting heart health benefits," he said.
Erdman was disappointed but not surprised with the FDA's announcement, he said.
After all, he said, the FDA has been "under tremendous pressure" from anti-soy groups like the Weston A. Price Foundation to revoke the claim, despite some studies suggesting that soy has health benefits. The foundation is a nonprofit that works to restore what it calls nutrient-dense foods to the human diet, according to its website.
The history of soy and health claims
"There was a sufficient amount of data prior to 1999 to suggest that 25 grams of soy protein a day was sufficient to lower cholesterol, assuming you had an otherwise appropriate diet," said Erdman, who authored a statement paper in the journal Circulation in 2000 that concluded "it is prudent to recommend including soy protein foods in a diet low in saturated fat and cholesterol to promote heart health."
Then, in 2008, the American Heart Association stated that there was not enough evidence to claim a strong link between soy protein and the reduced risk of coronary heart disease.
Last year, the FDA denied a citizen petition submitted by the Weston A. Price Foundation, requesting that the health claims about soy protein and reduced risk of heart disease be revoked.
Now, "while some evidence continues to suggest a relationship between soy protein and a reduced risk of heart disease -- including evidence reviewed by the FDA when the claim was authorized -- the totality of currently available scientific evidence calls into question the certainty of this relationship," said the statement from the FDA's Mayne.
"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 statement said.
On Monday, the American Heart Association said in an emailed statement that its "position on soy protein and coronary heart disease remains the same as outlined in our 2008 comment letter. Moving forward, we will carefully review the FDA's proposed rule, especially the possibility that the FDA may allow a qualified health claim related to soy and heart disease, because in this instance we are concerned that consumers may not understand the claim or that it is based on limited evidence."
What is a health claim?
Qualified health claims do not require as much scientific evidence as is required for an authorized health claim.
Authorized health claims are reviewed by the FDA and typically allowed on food labeling to show that a food or food component may reduce the risk of a disease or a health-related condition. However, such claims must be supported by scientific evidence.
The FDA's proposed rule to reverse the claim sets in motion a 75-day public comment period. The comments, along with all related research, will be reviewed to consider whether the rule will become final. If it does, the FDA said, a qualified health claim may be permitted if the agency feels there is evidence to support one.
The authorized health claim is one of 12 such claims allowed on foods. Other examples include the benefits of calcium and vitamin D to reduce risk of osteoporosis, some fruits and vegetables preventing cancer and folic acid preventing birth defects.
The FDA has been evaluating health claims on packaged foods since 1990, it said.
The take-away message for consumers should be to maintain a healthy daily diet as a whole to benefit your heart health and not focus too much on individual food items or nutrients, Watson said.
"You can actually prevent many diseases with lifestyle," she said.