Vegetarian diet may help mitigate cardiometabolic risk finds meta-analysis.

Plant-based diets are known to improve cardiometabolic risk in the general population, but their effects on people at high risk of cardiovascular diseases (CVDs) remain inconclusive. In a recently published meta-analysis of 20 randomized clinical trials, authors Wang et al have concluded that consuming a vegetarian diet may significantly improve cardiometabolic outcomes beyond standard pharmacological therapy in individuals at high risk of CVDs, highlighting the potential protective and synergistic effects of vegetarian diets for the primary prevention of CVD.

Despite major therapeutic advancements, cardiovascular diseases (CVDs) remain the leading cause of disease burden and escalating health care costs worldwide. Accumulating data from meta-analyses of randomized clinical trials (RCTs) suggest a role of vegetarian diets in the primary prevention of CVDs in the general population, but little is known on their effectiveness in patients with or at high risk of CVDs.

In the current study, authors sought to assess the association of vegetarian diets with major cardiometabolic risk factors, including low-density lipoprotein cholesterol (LDL-C), hemoglobin A1c (HbA1c), systolic blood pressure (SBP), and body weight in people with or at high risk of CVDs.

Twenty RCTs involving 1878 participants were included, and mean duration of intervention was 25.4 weeks. Four studies targeted people with CVDs, 7 focused on diabetes, and 9 included people with at least 2 CVD risk factors. Overall, relative to all comparison diets, meta-analyses showed that consuming vegetarian diets for an average of 6 months was associated with decreased LDL-C by 6.6mg/dl, HbA1c by 0.24%, and body weight by 3.4kgs. The association with SBP was not significant.

The GRADE assessment showed a moderate level of evidence for LDL-C and HbA1c reduction.

“The greatest reduction in LDL-C was observed in individuals at high risk of CVD. Vegetarian diets were most effective in glycemic control among people with type 2 diabetes, and led to favorable changes in weight in people at high risk of CVD and in those with type 2 diabetes, suggesting that vegetarian diets might have a synergistic (or at least nonantagonistic) use in potentiating the effects of optimal drug therapy in the prevention and treatment of a range of cardiometabolic diseases”, noted authors in discussion.

Driving home the point that not all vegetarian diets are equally healthy, the authors point out that more than one-third of the studies in the meta-analysis did not emphasize consumption of minimally processed, plant-based whole foods. “Vegetarian diets, particularly those practiced for ethical reasons or focused on convenience, may contain high levels of so-called empty calories, refined carbohydrates, hydrogenated oils, high-fructose corn syrup, sucrose or artificial sweeteners, and salt, Wang et al note.

More research needs to be done to understand whether specifically excluding animal-sourced foods can achieve better cardiometabolic health beyond what’s gained by the improved diet quality that often comes with vegetarianism.

Source: JAMA Network Open: doi:10.1001/jamanetworkopen.2023.25658