The U.S. Food and Drug Administration thinks the evidence linking the consumption of soy to heart health is … not so good.
However, Canadian experts still have a place in their hearts for soy’s cholesterol-lowering power.
Since 1999, the FDA has allowed products like soy milk and tofu to carry a claim that consuming 25 grams of soy protein per day “as part of a diet low in saturated fat and cholesterol, may reduce the risk of heart disease.”
Now the agency has announced plans to remove or water down that language. If the change goes through, it will mark the first time the FDA has gone backsies on any health claim approved for a food.
Many studies show eating soy protein – especially instead of something that comes with a side of saturated fat, like red meat – can result in a small but significant reduction in LDL or “bad” cholesterol, a major risk factor for heart disease and stroke.
But the results of such studies have gotten less dramatic over time. Looking at the whole body of research, including papers published since 1999, “calls into question the certainty of this relationship,” between soy and heart health, the FDA said in its statement.
Based on its review of 79 studies, Health Canada greenlit a similar health claim in 2015. Food labels north of the border say eating 25 grams of soy protein per day helps lower cholesterol, and high cholesterol is linked to heart disease, letting the consumer make the connection.
The Canadian claim is fair, said U of T medicine and nutrition professor Dr. David Jenkins.
“This is a bad move from the U.S.; I can’t understand it,” he said. Though the benefits of eating soy are “not vast,” nor as dramatic as cholesterol-lowering drugs like statins, they’re real, he explained: A three to five per cent reduction in LDL cholesterol, rising as high as 11 per cent if soy is replacing fatty meats.
Jenkins pioneered the “portfolio diet.” It combines four foods that lower cholesterol a bit, individually — nuts, soy, plant sterols (added to margarine) and barley or oat fibre — to create a significant effect that rivals prescription drugs’ up to 30 per cent cholesterol reduction.
Peter Jones, Canada Research Chair in Functional Foods and Nutrition at the University of Manitoba, explained one reason recent studies have failed to show many (or any) heart-health benefits of eating soy.
It’s not that soy doesn’t lower cholesterol — it does. It’s just that switching to soy is most beneficial for someone on a “train-wreck diet,” high in saturated fat, white sugar and white flour, Jones said, as most patients were when early studies were done in the 1960s
But today, people are smoking less, exercising more, and eating more fruits and vegetables and less meat, and “maybe soy isn’t going to make as much of a dent,” he said, adding that the time may come to re-evaluate: “Maybe the health claim should be revoked.”