Plant-based diets need to include certain food groups to benefit heart health, study finds

By Sally Robertson, B.Sc.Mar 18 2020

A new study conducted in Greece suggests that following a plant-based diet does not necessarily reduce the risk of cardiovascular disease. Rather, the diet needs to be focused on certain, healthy food groups for this benefit to be seen.

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The study, which is being presented at the American College of Cardiology's Annual Scientific Session Together with World Congress of Cardiology, found that people on a plant-based diet that included less healthy foods such as refined grains or sweets showed no significant benefit in terms of cardiovascular disease risk compared with people who did not follow a plant-based diet.

Lead author of the study, Demosthenes Panagiotakos (Harokopio University of Athens), says: "Based on these results, it seems that simply following a plant-based or vegetarian diet is not enough to reduce cardiovascular disease risk. It is also important to focus on specific, healthful plant-based food groups to see a benefit in terms of reducing cardiovascular disease."

Plant-based diets are becoming increasingly popular

Dietary patterns that include more plant-derived foods are becoming increasingly popular in many parts of the world due to the perceived health benefits. These diets are not always vegetarian or vegan, but typically, they do include more plant-derived foods such as wholegrains, seeds and pulses, and few or no meat, eggs, and dairy products.

For the current study, Panagiotakos and team monitored the eating habits of more than 2,000 Greek adults and tracked the development of cardiovascular disease among them over a ten-year period. At enrollment in 2002, participants answered a comprehensive food frequency questionnaire, which they also completed five years and ten years later.

After ten years, the team assessed the association between participants’ eating habits and the development of cardiovascular disease using a dietary index that categorized them into three groups according to how many animal-derived foods such as meat, eggs, and dairy products they consumed on a daily basis.

The team reports that, overall, men who consumed fewer animal-based foods were at a 25% decreased risk for cardiovascular disease, compared with men who consumed more of these foods. This trend was also observed among women, although it was less significant, with an overall reduction in disease risk of 11% seen among those eating the least amount of animal-derived foods.

Interestingly, although the between-group differences in disease risk were significant, the difference in the amount of animal foods consumed was relatively little. Participants with more plant-based diets ate an average of three animal-based foods per day, compared with five per day among participants with diets that were less focused on plant-based foods.

Even a small reduction in less healthy foods may contribute to heart health

Panagiotakos says: "These findings highlight that even a small reduction in the daily consumption of animal-based products-- principally the less healthy foods, such as processed meat products--accompanied by an increase in healthy plant-based foods may contribute to better cardiovascular health.”

Next, the researchers focused only on participants who followed plant-based diets and divided them into two groups: those who followed a healthy diet rich in fruits, vegetables, legumes, whole grains, nuts, oils and tea or coffee and those who followed an unhealthy diet that included more sweetened drinks, juices, refined grains, sweets, and potatoes.

The researchers found that only those in the healthy plant-based diet group were at less risk for cardiovascular disease than participants who followed a more animal-based diet.

Differences in eating habits and cardiovascular risk between men and women

Differences in eating habits and any related reduction in disease risk were also seen between males and females. Overall, men tended to eat approximately three times daily, while women tended to snack more and eat about four to five times per day. Among those participants in the unhealthy plant-based group, women saw a more significant reduction in cardiovascular disease risk than men and among those in the healthy plant-based group this risk reduction was even greater.

Panagiotakos says the findings suggest that snacking on healthy foods throughout the day could provide a health benefit, whereas snacking on unhealthy foods could increase disease risk.

Implications for future dietary guidelines

The team acknowledges that the study was limited by participants’ self-reporting of dietary habits, but say the findings still support evidence that plant-based diets could be beneficial to heart health and could help guide dietary recommendations for reducing cardiovascular risk going forwards.

"In the future, I believe it will be useful if cardiovascular disease prevention guidelines offer clearer and specific nutrition suggestions, in terms of the types of foods that are recommended and the portions that should be consumed," says Panagiotakos.