Soy shows consistent heart-healthy benefits

There is a consistent cholesterol-lowering effect for soy protein, according to new research by the University of Toronto in Ontario and published in the Journal of the American Heart Association.

Researchers pooled data from dozens of clinical trials from the last twenty years, calling in to question the U.S. Food and Drug Administration's (FDA) current proposal to revoke the health claim for soy protein and heart disease.

The researchers showed a reduction from soy in both total cholesterol and low-density lipoprotein cholesterol, which can damage the heart. The effect is steady across all 46 trials that the FDA cited in 2017, when it first proposed to revoke the health claim for soy based on recent trials that showed variable results.

"At no time since the original claim for soy as a reducer of serum cholesterol has its ability been in question," says David Jenkins, MD, PhD, Sc.D., professor of nutritional sciences and of medicine at lead author. "It's been consistent since 1999. The data have not changed."

The researchers performed a cumulative meta-analysis, which let them look at the effect of soy in all the trials combined, but at different points in time with the addition of data from each new trial. The FDA will likely decide on the health claim for soy this summer. Options include a full retraction and retention of a qualified health claim, according to a statement by agency representatives.

The study was funded by the Canada Research Chairs Program, a PSI Graham Farquharson Knowledge Translation Fellowship, Diabetes Canada Clinician Scientist Award, and Banting & Best Diabetes Centre Sun Life Financial New Investigator Award for Diabetes Research.

Jenkins and colleagues in the 1980s pioneered the glycemic index, which shows the effect of various foods on blood sugar levels. More recently, he helped develop a dietary portfolio that includes nuts, plant-based protein, viscous fiber, and plant sterols, which together can lower risk factors for heart disease by up to 30 percent.

This portfolio of foods has been incorporated into dietary guidelines by Heart U.K. and the European Atherosclerosis Society, among others. Health Canada released a national food guide that encourages plant-based eating this year, and the FDA maintains health claims for several other plant foods in the dietary portfolio.

"It's disheartening that the FDA has focused on soy," says Jenkins. "We see similar data for other foods in the portfolio. If you knock out one leg of that stool then the others could be up for grabs, right when concerns about health and the environment are bringing plant-based eating into the mainstream.

Companies such as Beyond Meat and Impossible Foods have seen huge growth this year with plant-based alternatives to meat. Burger King plans to offer its soy-based burger nation-wide in the U.S. by the end of 2019.

"We're moving into an age of plant-based protein, and it would be a shame to see that shift undermined," says Jenkins. "Plant-based food producers, industry, and retailers need all the help they can get to make their products accessible."