Not All Plant-Based Diets Are Equally Healthy

Highlights

• Plant-based diets lower the risk of heart disease
• In the recent study, the risk of heart disease increases with certain plant-based foods that includes refined grains and sugar sweetened beverages
• A plant-based diet that includes vegetables, whole grains, legumes and fruits with few or no animal products reduces the risk of heart disease

Plant-based diets reduce the risk of heart disease. But, a recent study revealed that some plant-based diets increase the risk of heart disease. The study was published in the Journal of the American College of Cardiology.// What is a Plant-based Diet?
A plant-based diet is a diet based on foods derived from plants (like vegetables, whole grains, legumes and fruits) but with few or no animal products. It is increasingly becoming recognized as the most healthy diet. A plant based diet decreases the risk of coronary artery disease and a diet high in fruits and vegetables lowers the risk of high blood pressure, stroke, and colorectal cancer.

In prior studies, there were several limitations, like plant-based diets were also defined as "vegetarian" diets, which consisted of various dietary patterns that excludes some or all animal foods.

Certain Plant-based Foods Increase Risk of Heart Disease

All plant foods were treated equally in all these studies. Although, few plant foods, such as refined grains and sugar sweetened beverages were linked to increased risk of cardio-metabolic disease.

Researchers created three versions of a plant-based diet to overcome these limitations, which include:

• An overall plant-based diet - which emphasizes on the consumption of all plant foods by reducing (but did not eliminate) animal food intake;
• A healthful plant-based diet - which emphasizes on the intake of healthy plant foods. Ex: whole grains, fruits and vegetables; and
• An unhealthful plant-based diet - which emphasizes on the consumption of less healthy plant foods. Ex: refined grains.

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The researchers used a baseline sample of about 73,710 women from the Nurses’ Health Study, 92,320 women from the Nurses’ Health Study 2 and about 43,259 men from the Health Professionals Follow-Up Study.

The participants of the study responded to a follow-up questionnaire every two years for over two decades. The questionnaire consisted of questions related to lifestyle, health behaviors and medical history.

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In this study, participants with coronary heart disease, cancer, stroke and coronary artery surgery at baseline were excluded and during the follow-up, over 8,631 participants developed coronary heart disease.

Research Findings of the Study

Overall, it was found that a plant-based diet significantly lowers the risk of heart disease. Consuming more healthier plant-based diets like one rich in whole grains, fruits, vegetables, etc., was found to substantially lower the risk of heart disease. But, an opposite effect was seen in a plant-based diet that emphasized less healthy plant foods, like including sweetened beverages, refined grains, potatoes and sweets.

"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," said Ambika Satija, ScD, a postdoctoral fellow at the Harvard T.H. Chan School of Public Health in Boston and the study’s lead author.

Apparently, there is a wide variation in the nutritional quality of plant foods, which makes it crucial to consider the quality of foods in a plant-based diet.

Kim Allan Williams, MD, MACC, chair of the division of cardiology at Rush University Medical Center in Chicago, in an accompanying editorial said that this study adds up to the substantial evidence which proves that plant-based diets reduce heart disease risk.

Not all plant-based foods are equally healthy. As plant-based diets with whole grains, unsaturated fats and an abundance of fruits and vegetables "deserve more emphasis in dietary recommendations."

Williams said that the long-term follow up enabled researchers to examine the dietary patterns of the participants and analyzed the effect of gradual adherence to a plant-based diet by reducing the consumption of animal foods and increasing the intake of plant foods on the risk of heart disease.

The authors said "just as physical activity is a continuum, perhaps an emphasis on starting with smaller dietary tweaks rather than major changes would be more encouraging and sustainable."

The limitations of the study were its observational nature and the self-reported diet assessments, but these diet assessments were validated against multiple week diet records and biomarkers.

Reference

1. Ambika Satija, et al. Healthful and Unhealthful Plant-Based Diets and the Risk of Coronary Heart Disease in U.S. Adults. Journal of the American College of Cardiology, Volume 70, Issue 4, Pages 411-422. DOI:10.1016/j.jacc.2017.05.047

Source-Medindia