Vegetarian Diet Improves Cardiometabolic Profile in Patients at High Risk for Cardiovascular Diseases

Consuming a poor diet is associated with an elevated risk of cardiovascular morbidity and mortality. Current guidelines from the American Heart Association and Diabetes organizations as well as supportive evidence from clinical studies emphasize on vegetarian diets for prevention of  heart diseases, type 2 diabetes and some of its metabolic complications.

Though the benefits of vegetarian diet for prevention of cardiovascular diseases (CVD) in healthy general population is well known, the impact of this diet on people with or at high risk for CVD is not well delineated. A recent meta-analysis by Wang et al., published in the journal, JAMA Network Open, reported the beneficial effects of vegetarian diet in the reduction of low-density lipoproteins cholesterol (LDL-C), body weight, and glycated haemoglobin (HbA1c) beyond the standard therapy in patients with high CVD risk (presence of at least two risk factors for CVD).

This meta-analysis included 20 randomized controlled trials (1878 total participants; mean age: 28─64 years; mean duration of intervention: 25.4 weeks), which delivered vegetarian diets to adults at risk for CVD and measured cardiometabolic parameters such as low-density lipoprotein cholesterol (LDL-C), glycated hemoglobin (HbA1c), body weight, and systolic blood pressure (SBP). Pre- and post-intervention measurements of LDL-C, HbA1c, and SBP were recorded along with changes in body weight and energy intake.

Diet followed in majority of studies included vegan diets (animal product and added fat-free diet, containing only whole-food plant-based options, with Vitamin B12 supplementation), lacto-ovo-vegetarian diets (meat-free but contains egg whites, low-fat dairy, gluten, soya, nuts, vegetables, and fruits), and lacto-vegetarian diets(meat, egg, and added fats-free diet; contains fruits and vegetables, grains, and legumes; animal products limited to ≤1 portion of low-fat yogurt; vitamin B12 supplement).

The study results are summarized below (effects are beyond that reached with standard therapy):

1. Overall benefits of vegetarian diet: After about 6-months of the diet, vegetarian diets resulted in a significant reduction in LDL-C, HbA1c, and body weight in patients with CVD/high risk of CVD and type 2 diabetes. (p<0.001, See Part A of the graphic).
2. Effect on LDL-C:Reduction in LDL-C was noted in studies with or without energy restrictions, physical activity interventions and changes in the dosage of lipid-lowering medications. Among all the dietary approaches, the most significant reduction in LDL-C was observed with lacto-ovo vegetarian diets (−14.1 mg/dL).
3. Patients with high CVD risk:Among those with a high risk of CVD, vegetarian diet resulted in more pronounced decreases in LDL-C and body weight (See Part B of the graphic).
4. Patients with type 2 diabetes:A notable reduction in HbA1C (−0.36%) and body weight (−2.8 kg) were noted with vegetarian diet plan. Reduction in HbA1c was noted in studies with or without energy restrictions or physical activity interventions.
5. Effect on SBP: The effect of vegetarian diets on SBP was not statistically significant (−0.1 mmHg).

Clinical Implications

1. Consuming a vegetarian diet resulted in a moderate, yet notable impact on concurrently decreasing several risk factors associated with CVD (LDL-C, HbA1c, and body weight) in patients with high CVD risk and type 2 diabetes.
2. Combining such a diet with effective drug therapy could enhance the outcomes in the primary prevention and treatment of a variety of cardiometabolic conditions.

(Source: Viguiliouk E, Kendall CW, Kahleová H, Rahelić D, Salas-Salvadó J, Choo VL, Mejia SB, Stewart SE, Leiter LA, Jenkins DJ, Sievenpiper JL. Effect of vegetarian dietary patterns on cardiometabolic risk factors in diabetes: A systematic review and meta-analysis of randomized controlled trials. Clin Nutr. 2019;38(3):1133-45.)