Opting for plant-based diets may reduce risk of death due to heart disease

08 Mar 2019 --- Incorporating more fruit and vegetables into one’s diet may reduce the risk of death due to heart disease and increase longevity. This is according to research from the American Heart Association’s (AHA) Epidemiology and Prevention, Lifestyle and Cardiometabolic Health Scientific Sessions 2019. The findings showed that replacing one portion of unhealthy foods per day with one portion of healthy foods and increasing the consumption of fruit and vegetables reduces the risk of death by 10 percent. 

“Not all plant-based diets are equal, but boosting the intake of high-quality plant-based foods over time lowers the risk of death even among people who started off with poor-quality diets,” notes Dr. Megu Baden, lead author of the study and Postdoctoral Research Fellow in the Department of Nutrition at the Harvard T.H. Chan School of Public Health in Boston, US.

Previously, studies have shown that consuming a primarily plant-based diet can reduce the risk of developing diabetes and heart disease. This new study, however, is the first one to examine how a shift in dietary habits can impact a person’s risk of dying, regardless of where they started from. 

“What our study shows is that increasing plant-based diet quality over time is associated with a lower risk of mortality, while increasing the consumption of an unhealthy plant-based diet was associated with a higher risk of mortality. Specifically, our study reflects what happens when individuals change their diet in the real world, and we think this is a meaningful approach,” Baden tells NutritionInsight.

“The results were in line with a previous study on the associations of plant-based diet indices with the risk of Type 2 diabetes and congenital heart defect (CHD). We think our results emphasize the importance of considering the quality of plant foods.”

Starting in 1998, the researchers followed roughly 74,000 people for a period of 12 years. They followed 48,000 women participating in the Nurses’ Health Study, with an average age of 64 years, and 26,000 men with an average age of 64 years, participating in the Health Professionals Follow-Up Study. None of the subjects had a history of cancer or heart disease when they entered the study. Using dietary reports, participants were assessed on changes in their diet over the 12 years prior to entering the research. 

The researchers developed three diet scales that looked into the overall consumption of plant-based foods, such as vegetables, whole grains and fruits, and the consumption of lower-quality plant-based foods, including fruit juices, potatoes and sweets.

The results of the study showed that when compared to participants who had fairly stable diets, during the 12-year follow-up period (1998 to 2014) the causes of all death were:

• 8 percent lower in those with the sharpest increase in an overall plant-based diet;
• 10 percent lower in those with the biggest increase in a healthy plant-based diet;
• 11 percent higher in those with the biggest increase in an unhealthy plant-based diet.

Additionally, a 10 percent lower risk of death from heart disease was linked to a ten point increase in score on the healthy plant-based diet scale, meaning participants who replaced one serving of refined grains with whole grains and increased fruit and vegetables by one serving per day. A ten point increase in score on the unhealthy plant-based diet scale was associated with a 6 percent higher risk of cardiovascular disease-related death, the research highlighted.

“Over time, consuming more whole grains, fruits and vegetables, while decreasing your intake of refined grains, sweets and desserts and animal foods such as animal fat meat and miscellaneous animal-based foods, may lower your risk of death from heart disease and other causes,” Dr. Baden says.

The study’s results were adjusted depending on age, race, initial diet score, body mass index (BMI), weight change and family history of diabetes, heart attack and cancer, medications, menopausal influences and hormone use, smoking and lifestyle influences. The research cannot, however, prove a causal relationship between the dietary changes and risk of death, as it was not a randomized trial study, note the researchers. As the study followed health professionals of European ancestry, the researchers note that the results shouldn’t be generalized.

Baden says they wish to conduct more research on the matter and replicate the findings in other large cohorts. “We would also like to examine the mechanisms underlying the association between improved plant-based diet quality and lower mortality risk by examining metabolomic signatures of a healthy and unhealthy plant-based diet.”

The AHA and the American College of Cardiology recommend a flexitarian type of diet, that emphasizes vegetables, fruits and whole grains and includes low-fat dairy products, poultry, fish and legumes. Intake of saturated fats, sodium, sugar-sweetened beverages and red meats should be limited, according to the guidance. 

In related news, emerging research touts the benefits of the increasingly popular flexitarian diet, which combines all the benefits of vegan, vegetarian and animal-based diets. A recent Nestlé Research study carried out in collaboration with the University of Hawaii Cancer Center, found that the levels of macro and micronutrients in each meal were more important than the type of diet consumed, suggesting that a flexitarian or semi-vegetarian diet may be most beneficial for overall health.

Another study found that a plant-based diet can improve the secretion of insulin and incretin hormones in those with Type 2 diabetes. The findings underline possible health benefits of following a plant-heavy diet and come at a time when interest in plant-based lifestyles is at an all-time high.

Moreover, a plant-based diet may affect not only physiological health but psychological as well. According to a longitudinal study from the University of Leeds, UK, the daily consumption of fruit and vegetables can improve mental wellbeing. Increasing the frequency and quantity of consumption may also affect mental health. Although the association between mental health and fruit and vegetable intake appears to be strong, the researchers note more research is needed to determine whether this is causal.

By Kristiana Lalou