Not all plant-based diets created equal, study finds

18 Jul 2017 --- Plant-based diets are often recommended to reduce the risk of heart disease; however, some plant-based diets are actually associated with a higher risk of heart disease, according to a study published in the Journal of the American College of Cardiology.

“Plant Powered Growth” was one of Innova Market Insights’ Top Trends for 2017, highlighting increased demand for plant-based foods from those who do not want to commit to a full vegan or even vegetarian lifestyle. However, the study suggests that not all plant-based diets are created equal.

Several limitations marked previous research on the impact of a plant-based diet. Prior studies treated all plant foods equally, even though certain plant foods – like refined grains and sugar sweetened beverages – are associated with a higher risk of cardio-metabolic disease.

To overcome these limitations, the researchers created three versions of a plant-based diet: an overall plant-based diet which emphasized the consumption of all plant food and reduced, but did not eliminate, animal food intake; a healthful plant-based diet that emphasized the intake of healthy plant foods such as whole grains, fruits and vegetables; and an unhealthful plant-based diet which emphasized consumption of less healthy plant foods.

Researchers used a baseline sample of 73,710 women from the Nurses’ Health Study, 92,320 women from the Nurses’ Health Study 2 and 43,259 men from the Health Professionals Follow-Up Study. These participants responded to a follow-up questionnaire every two years for over two decades.

During follow-up, 8,631 participants developed coronary heart disease. Overall, adherence to a plant-based diet was associated with a lower risk of heart disease. However, a plant-based diet that emphasized less healthy plant foods like sweetened beverages, refined grains and potatoes had the opposite effect.

“When we examined the associations of the three food categories with heart disease risk, we found that healthy plant foods were associated with lower risk, whereas less healthy plant foods and animal foods were associated with higher risk,” says Ambika Satija, Sc.D, a postdoctoral fellow at the Harvard T.H. Chan School of Public Health in Boston and the study’s lead author.

In an accompanying editorial, Kim Allan Williams, MD, MACC, chair of the division of cardiology at Rush University Medical Center in Chicago, says the long-term follow up allowed authors to examine the effect of gradual adherence to a plant-based diet through reduced animal food intake: “Perhaps an emphasis on starting with smaller dietary tweaks rather than major changes would be more encouraging and sustainable.”

There may be an appetite for these tweaks – according to a consumer survey recently conducted by the California Walnut Board, many fear that the flavor and texture meat offers may be compromised by switching to a plant-based diet. But 83 percent of Americans are open to making plant-based dishes, particularly if the texture and flavor is comparable to recipes containing meat. The board suggests that it’s time to provide “more than just a vegetarian option.”

Williams believes that the study nevertheless adds to the substantial evidence in favor of plant-based diets with whole grains, unsaturated fats and an abundance of fruits and vegetables.