Not All Plant-Based Diets Are Equal: Study Links Healthier Choices to Lower Death Risk

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A new study found that plant-based diets can be both helpful and harmful, depending on the quality of the foods consumed.

“Among populations with cardiometabolic disorders, higher adherence to a healthful plant-based diet was significantly associated with a lower risk of total, cardiovascular and cancer mortality,” said lead investigator Zhangling Chen, M.D., Ph.D., of the Department of Cardiovascular Medicine at the Second Xiangya Hospital of Central South University in Changsha, China. “More intake of healthy plant-based foods, less intake of unhealthy plant-based foods and less intake of animal-based foods are all important.”

The research, which will be presented at the American College of Cardiology’s Annual Scientific Session, held March 29-31 in Chicago, is the first to investigate how plant-based diets affect people with heart disease, diabetes and other metabolic conditions.

The team followed nearly 78,000 people with cardiometabolic disorders living in the United States, the United Kingdom and China for more than a decade. These included 18,332 individuals in the U.S. from the National Health and Nutrition Examination Study (NHANES), approximately 55,000 adults from the U.K. Biobank, and 4,485 in China from the Chinese Longitudinal Healthy Longevity Study (CLHLS).

Participants were asked about their food choices using 24-hour dietary recall interviews or dietary questionnaires at baseline. Investigators adjusted for lifestyle factors, dietary factors and demographics.

They then assigned a score on two indexes: a healthful plant-based diet index (hPDI) and an unhealthful plant-based diet index (uPDI). Healthy plant-based foods included fruits, vegetables, legumes, whole grains, tea and coffee, while unhealthy foods were potatoes, refined grains and sugar-sweetened drinks.

During the follow-up period, 14,274 deaths in NHANES and 2,881 deaths in CLHLS were reported.

Results showed that eating a healthy plant-based diet was linked to a 17% to 24% lower risk of death, including of cardiovascular disease and cancer. However, eating an unhealthy plant-based diet was associated with a 28% to 36% higher risk of death. These results were similar in people with different types of cardiometabolic disorders and among participants who lived in different geographical locations. They were also consistent across subgroups that analyzed age, sex, race, alcohol intake, smoking status, physical activity and body mass index (BMI).

The findings suggest that not all plant-based diets are equal, and choosing whole, nutrient-rich plant foods may help people with cardiometabolic conditions live longer.

A separate study that analyzed only NHANES data and did not focus on people with cardiometabolic disorders showed a healthy beverage pattern — one high in tea, coffee and low-fat milk and low in whole-fat milk, fruit juice, sweetened beverages and alcohol — was also linked to a lower risk of premature death.

Investigators noted limitations of the study including that dietary data were collected only at baseline, so changes in dietary choices could not be assessed. Additionally, some confounding factors were difficult to remove. They suggested that future research enrolling more diverse groups could help to confirm the findings across broader populations.

“These findings may help individuals with cardiometabolic disorders make healthier lifestyle choices,” Chen said. “It is important to identify and develop cost-effective strategies to promote health among individuals with cardiometabolic disorders.”