Abstract
Cardio-metabolic disease, namely ischemic heart disease, stroke, obesity, and type 2 diabetes, represent substantial health and economic burdens. Almost one half of cardio-metabolic deaths in the U.S. might be prevented through proper nutrition. Plant-based (vegetarian and vegan) diets are an effective strategy for improving nutrient intake. At the same time, they are associated with decreased all-cause mortality and decreased risk of obesity, type 2 diabetes, and coronary heart disease. Evidence suggests that plant-based diets may reduce the risk of coronary heart disease events by an estimated 40% and the risk of cerebral vascular disease events by 29%. These diets also reduce the risk of developing metabolic syndrome and type 2 diabetes by about one half. Properly planned vegetarian diets are healthful, effective for weight and glycemic control, and provide metabolic and cardiovascular benefits, including reversing atherosclerosis and decreasing blood lipids and blood pressure. The use of plant-based diets as a means of prevention and treatment of cardio-metabolic disease should be promoted through dietary guidelines and recommendations.
Generated Summary
This review article presents evidence that plant-based diets may be an effective strategy for improving nutrient intake and preventing and treating cardio-metabolic diseases. It examines the association of plant-based diets (vegetarian and vegan) with various cardio-metabolic benefits, including reduced risk of cardiovascular disease, obesity, type 2 diabetes, and hypertension. The review is based on the most recent findings, giving special attention to systematic reviews and meta-analyses, particularly those drawing on randomized clinical trials, with observational studies included as supporting evidence. The review investigates the impact of these diets on cardiovascular disease, body weight, metabolic syndrome, glycemic control, and blood pressure. Furthermore, it explores the potential mechanisms behind these benefits and concludes with recommendations for promoting plant-based diets in dietary guidelines.
Key Findings & Statistics
- Cardio-metabolic deaths in the U.S.: 45.5% could be prevented through proper nutrition.
- Plant-based diets may reduce the risk of coronary heart disease events by an estimated 40%.
- Plant-based diets may reduce the risk of cerebral vascular disease events by 29%.
- Plant-based diets may reduce the risk of developing metabolic syndrome and type 2 diabetes by about one half.
- In the European Prospective Investigation into Cancer and Nutrition study, vegetarians had a 32% lower risk of developing coronary heart disease, compared with non-vegetarians.
- In a systematic review and meta-analysis of 8 prospective studies among Seventh-day Adventists, vegetarian diets were associated with a 40% reduced risk of coronary heart disease events and a 29% reduction in cerebral vascular disease events, compared with non-vegetarians.
- A recent systematic review and meta-analysis of 86 cross-sectional and 10 cohort prospective studies reported a significant protective effect of a vegetarian diet against the incidence and/or mortality from ischemic heart disease. The observed risk reduction, compared with non-vegetarian dietary patterns, was 25%.
- Vegetarians typically have lower BMI (body mass index) values, compared with non-vegetarians.
- In the Adventist Health Study-2, BMIs were lowest among vegans (23.6 kg/m²), higher in lacto-ovo-vegetarians (25.7 kg/m²), and highest in nonvegetarians (28.8 kg/m²).
- A recent study showed a mean BMI reduction of 4.4 kg/m² with a 6-month, whole-food, plant-based diet with no energy restrictions, compared with usual care (0.4 kg/m²), in overweight or obese subjects.
- Plant-based diets were associated with a mean weight reduction of –2.02 kg (95% confidence intervals (CI), −2.8 to −1.23 kg).
- A vegan diet had a more pronounced effect (-2.52 kg; 95% CI, −3.02 to −1.98 kg) than a lacto-ovo-vegetarian diet (-1.48 kg; 95% CI, −3.43 to 0.47 kg).
- A meta-analysis of 15 clinical trials using vegetarian or vegan diets showed an average weight loss range of 4.6 kg among study completers.
- Plant-based diets appear to reduce the risk of developing metabolic syndrome by about one half.
- Diabetes prevalence has been found to be the lowest among vegans (Odds ratio (OR) 0.51; 95% CI 0.40-0.66) and lacto-ovo-vegetarians (OR 0.54; 95% CI 0.49–0.60), compared with non-vegetarians.
- Vegetarian diets have been shown to be helpful not only in prevention but also in the treatment of type 2 diabetes in several clinical trials.
- A 2014 meta-analysis found that a plant-based diet significantly improves blood sugar control in type 2 diabetes. The benefit of omitting meat, cheese, and eggs was as much as 0.7 points in some studies, and averaged about 0.4 points overall.
- Plant-based diets on glycemic control comes from six randomized controlled trials, summarized in a recent meta-analysis, as well as observational studies.
- It has been estimated that 874 million adults worldwide have a systolic blood pressure of 140 mm Hg or higher.
- High protein intake, especially from meat, increases blood pressure.
- A meta-analysis of 7 randomized controlled trials and 32 observational studies found that vegetarian diets lower blood pressure (both systolic and diastolic), compared with omnivorous diets.
- In observational studies, vegetarian diets were associated with blood pressure readings that were, on average, 6.9 mm Hg and 4.7 mm Hg lower for systolic and diastolic blood pressure, respectively.
- In randomized controlled trials, vegetarian diets decreased both systolic and diastolic blood pressure by 4.8 and 2.2 mm Hg, respectively.
- The reduction in systolic blood pressure by 5 mm Hg is estimated to result in a 7% reduction in all-cause mortality, a 9% reduction in mortality due to coronary heart disease, and a 14% reduction in mortality due to stroke.
- Epidemiological studies have shown a high prevalence of hypercholesterolemia in Western countries (more than 50% adults have total cholesterol serum levels higher than 5 mmol/L).
- Data from clinical studies indicate that for every 1% reduction in LDL-cholesterol, the risk for a major cardiac event, including heart attack and stroke, is reduced by approximately 1%.
- Replacing saturated fat in the diet and replacing it with polyunsaturated vegetable oil can reduce the risk of cardiovascular disease by about 30%.
- A meat-free diet can lead to a significant reduction in total and LDL cholesterol, which corresponded with about a 10% reduced risk of heart disease, according to a meta-analysis of randomized-controlled trials published by the American Heart Association.
Other Important Findings
- Plant-based diets are an effective strategy for improving nutrient intake.
- Plant-based diets are associated with decreased all-cause mortality and decreased risk of obesity, type 2 diabetes, and coronary heart disease.
- Risk factors associated with heart disease are also less frequent among those following vegetarian diets.
- Plant-based diets appear to reduce the risk of individual components of the metabolic syndrome and are associated with lower waist circumference, lower concentrations of triglycerides, total and low-density lipoprotein (LDL) cholesterol, blood sugar, and blood pressure.
- Vegetarian diets have been shown to be helpful not only in prevention but also in the treatment of type 2 diabetes in several clinical trials.
- Management of glycemic control is one of the cornerstones of diabetes care.
- Vegetarian diets typically have higher fiber and potassium and lower fat, compared with omnivorous diets.
- Plant-based diets are also lower in saturated fat and dietary cholesterol.
- Vegetable proteins reduce the concentrations of blood lipids, reduce the risk of obesity and cardiovascular disease, and may have anti-inflammatory and anti-cancer effects.
- The cardio-metabolic benefits seem to be greater with vegan than lacto-ovo-vegetarian diets.
Limitations Noted in the Document
- The review acknowledges that while observational studies are included, the focus is on systematic reviews and meta-analyses of randomized clinical trials, implying that the evidence base is primarily focused on these types of studies. However, it doesn’t explicitly discuss the limitations of relying heavily on these types of studies, such as the potential for publication bias.
- The study acknowledges that there is a paucity of studies examining the effect of plant-based diets on platelet aggregation, which limits the evidence for its beneficial effects.
- The review notes that the number of studies on the topic of plant-based diets and glycemic control is limited, while acknowledging the concordance of results across studies is compelling.
- The review focuses on the benefits of plant-based diets, and does not necessarily include any discussion of the challenges of adhering to plant based diets such as the need for supplement to meet all nutritional needs.
Conclusion
The evidence presented in this review strongly supports the adoption of plant-based diets as a strategy for preventing and managing cardio-metabolic diseases. The consistent findings across randomized clinical trials and observational studies provide a compelling case for the effectiveness of these diets in reducing the risk of cardiovascular disease, obesity, type 2 diabetes, and hypertension. The benefits extend to various aspects of health, including improved glycemic control, weight management, and blood lipid profiles. A key takeaway is the potential for plant-based diets to reverse atherosclerosis and decrease blood lipids and blood pressure. The authors emphasize the need to promote plant-based diets through dietary guidelines and recommendations. The synergistic effects of whole plant foods, in comparison to isolated nutrients, are highlighted, suggesting that the comprehensive nature of these diets is crucial for achieving optimal health outcomes. The review’s findings suggest that the cardio-metabolic benefits are greater with vegan diets compared to lacto-ovo-vegetarian diets, and it is recommended that the use of plant-based diets be promoted through dietary guidelines and recommendations. In summary, the review underscores the substantial potential of plant-based diets as a means of preventing and treating cardio-metabolic diseases.