Healthy plant-based diets lower risks for mortality, major chronic conditions

Key takeaways:

• Greater adherence to a healthful plant-based diet was linked to lower risks for CVD, cancer and mortality.
• In contrast, adherence to an unhealthful plant-based diet had inverse associations.

Middle-aged adults with greater adherence to a healthful plant-based diet had significantly lower risks for CVD, cancer and mortality than those who had lower adherence, according to study results published in JAMA Network Open.

Alysha S. Thompson, MSci, a PhD researcher at Queen's University Belfast, and colleagues wrote that, for both health and environmental reasons, plant-based diets have recently gained popularity. However, strict plant-based diets may be associated with health consequences like calcium deficiencies, they noted, and there is no comprehensive evaluation of diet quality in relation to risk for mortality and major chronic diseases.

“Previous population-based studies have shown that plant-based diets per se may not be associated with improved health but that their composition is crucial with respect to a reduction in chronic disease risk,” they wrote. “Only a healthful plant-based diet, characterized by low consumption of both animal foods and processed foods of plant origin (eg, refined grains, sugary drinks, snacks and desserts) has been associated with a lower risk of type 2 diabetes, CVD and total mortality.”

Thompson and colleagues conducted a prospective cohort study to evaluate the potential health benefits and risks associated with plant-based diets. They specifically wanted to see if adhering to a healthful plant-based diet (hPDI) vs. unhealthful plant-based diet (uPDI) was linked to mortality and major chronic diseases like cancer and CVD.

The researchers used data from 126,394 U.K. Biobank participants — 55.9% of whom were women and 91.3% of whom were white — and measured their adherence to plant-based diets with 24-hour dietary assessments.

Thompson and colleagues found that an hPDI might be beneficial for health, regardless of genetic predisposition and established chronic disease risk factors.

Greater adherence to the hPDI was linked to lower risks for:

• cancer (HR = 0.93; 95% CI, 0.88-0.99);
• CVD (HR = 0.92; 95% CI, 0.86-0.99);
• ischemic stroke (HR = 0.84; 95% CI, 0.71-0.99);
• myocardial infarction (HR = 0.86; 95% CI, 0.78-0.95); and
• total mortality (HR = 0.84; 95% CI, 0.78-0.91).

Higher scores for the uPDI, however, were linked to higher risks for CVD, cancer and mortality.

The researchers noted that the associations did not show heterogeneity across strata of BMI, socioeconomic status, sex, smoking status or with polygenic risk scores.

“Importantly, we observed that inverse associations between the hPDI and CVD end points (total CVD, myocardial infarction, and stroke) were independent of genetic disease risk,” they wrote. “This finding is of particular public health relevance, as it suggests individual benefits of healthful PBDs irrespective of genetic predisposition for CVD.

At the same time, they added, “absolute risk reduction due to a healthful PBD may be greater among individuals with a stronger genetic predisposition for CVD, given their higher lifetime risk of CVD.”

Thompson and colleagues identified mechanisms that may underlie the associations between hPDI and lower risks for disease and mortality. Higher intake of unprocessed plant foods could reduce the risk for low-grade inflammation, impaired insulin sensitivity and obesity, they wrote, and these mechanisms could explain lower mortality risks because of both cancer and CVD.

“Similarly, plant constituents such as fiber may beneficially affect the composition and function of the large intestinal microbiome,” Thompson and colleagues wrote. “The fact that associations between hPDI and CVD revealed lower risks, especially of myocardial infarction and ischemic stroke compared with that for cancer in our study, suggests that additional CVD-specific mechanisms (eg, lower blood pressure or low-density lipoprotein cholesterol due to PBD6) further explain our findings.”