MONDAY, March 23, 2020 (HealthDay News) -- Eating tofu and other foods with high levels of isoflavones -- plant-based "phytoestrogens" -- could lower people's risk of heart disease, a new study suggests. The effect was especially strong in women.
"Other human trials and animal studies of isoflavones, tofu and cardiovascular risk markers have also indicated positive effects, so people with an elevated risk of developing heart disease should evaluate their diets," said study lead author Dr. Qi Sun. He's a researcher at Harvard's T.H. Chan School of Public Health in Boston.
In the new study, Sun's group tracked data on more than 200,000 Americans enrolled in long-term health and nutrition studies. All of them were free of cancer and heart disease when the studies began.
After accounting for a number of other factors associated with heart disease, the researchers concluded that eating tofu more than once a week was associated with an 18% lower risk of heart disease, compared to people who ate tofu less than once a month, who had an average 12% reduction in heart risk.
The reduced heart disease risk associated with regular tofu consumption was seen primarily in women before menopause or postmenopausal women who weren't taking hormones, according to the study published March 23 in the journal Circulation.
"Despite these findings, I don't think tofu is by any means a magic bullet," Sun said in a journal news release. "Overall diet quality is still critical to consider, and tofu can be a very healthy component."
"If their diet is packed with unhealthy foods, such as red meat, sugary beverages and refined carbohydrates, (people) should switch to healthier alternatives," he suggested. "Tofu and other isoflavone-rich, plant-based foods are excellent protein sources and alternatives to animal proteins."
Tofu is soybean curd, and whole soybeans such as edamame are rich sources of isoflavones. Other foods with high levels of isoflavones include chickpeas, fava beans, pistachios, peanuts and other fruits and nuts.
Soymilk tends to be highly processed and is often sweetened with sugar, Sun noted, and the study found no significant association between soymilk consumption and lower heart disease risk.
While the study found an association between tofu and other foods high in isoflavones and a lower risk of heart disease, it does not prove that such foods actually lower heart disease risk, Sun emphasized. Many other factors can affect heart disease risk, including exercise, family history and lifestyle habits, he noted.
"For example, younger women who are more physically active and get more exercise tend to follow healthier, plant-based diets that may include more isoflavone-rich foods like tofu," Sun said.
Two experts in nutrition and the heart agreed that a move away from meat to tofu may be healthy.
"Although the impact of specific isoflavone-rich food is still not clear; what is known is that increase in plant-based protein and lean, low carbohydrate, meals reduce overall cardiovascular risk," said Dr. Satjit Bhusri, a cardiologist at Lenox Hill Hospital in New York City. "This simple understanding and mindfulness of what to eat can make a major impact on overall cardiovascular health and outcomes."
Dr. Benjamin Hirsch directs preventive cardiology at Northwell Health's Sandra Atlas Bass Heart Hospital in Manhasset, N.Y. He noted that, "Isoflavones are thought to support heart health by their association with improvements in vascular function, reduction in total cholesterol, and reduction in inflammation."
"What is interesting is that premenopausal women derived the greatest benefits, which may suggest that it is the estrogen and hormonal component of soy-based food that leads to better outcomes in women," he added.
The U.S. National Library of Medicine has more on soy.