New study: vegetarian diets vs. non-vegetarians in the battle against cardiometabolic diseases

In a recent study published in Nutrition, Metabolism and Cardiovascular Diseases Journal, researchers conducted a comprehensive review to compare the impacts of vegetarian and non-vegetarian diets on the outcomes of major cardiometabolic and other noncommunicable diseases.

Study: A comprehensive review of the health effects of vegetarian diets. Image Credit: Elena.Katkova/Shutterstock.com

Background

Opinions on the association between meat consumption and health have been divided, with diets poor or devoid of animal food sources considered low in nutrition, resulting in deficiencies in essential nutrients.

Emerging research supports conflicting views that plant-based diets meet normal nutritional requirements and provide various health benefits, such as reducing the risks of multiple diseases.

However, the term “vegetarian” is used loosely to encompass various dietary patterns such as vegan, ovo-vegetarian, lacto-vegetarian, lacto-ovo-vegetarian, and semi-vegetarian.

Vegetarian diets also range from the Western patterns of vegetarianism mentioned above to ethnicity-based dietary patterns, such as Buddhist or Asian diets, where the availability of animal food sources or socio-economic or cultural factors influence the diet.

This wide range of variation in vegetarian diets has led to conflicting results among studies examining the relationship between vegetarian diets and health benefits.

Individuals in developing countries generally eat a more balanced and well-developed vegetarian diet than those in developing countries where access to food depends on socioeconomic factors.

About the studio

In the present study, researchers conducted a comprehensive review of research that examined various vegetarian diets and their effects on health-related outcomes, including the risks of various noncommunicable diseases.

We reviewed studies examining various types of vegetarian diets, from Western vegetarian dietary patterns to vegetarian diets influenced by religious beliefs.

Noncommunicable diseases examined in the review broadly included cardiovascular, cerebrovascular, cardiometabolic diseases, obesity, hypertension, dyslipidemia, metabolic syndrome, and type 2 diabetes.

Observational studies and randomized controlled trials comparing the effects of vegetarian diets with those of non-vegetarian or omnivorous diets were included.

In addition, for each NCD category, the researchers conducted an extensive literature search using a broad range of keywords associated with the disease.

The review included cohort studies, randomized controlled trials, longitudinal studies, and prospective cohort studies reporting the comparative effects of vegetarian and non-vegetarian diets in the context of disease risk.

Results

The results reported that while it appears that following vegetarian diets may help reduce the risk of cardiometabolic disease, the non-uniformity of results due to cultural and ethnic differences in approaches to vegetarianism as well as due to differences in methodology between studies make it difficult formulate definitive conclusions.

Several cohort studies in the review reported that following a vegetarian versus a non-vegetarian diet was beneficial in reducing the risk of incidence and mortality associated with obesity, overweight, and ischemic heart disease.

Vegetarian diets were also linked to a lower risk of hypertension and positively influenced plasma parameters and the risk of type 2 diabetes.

Furthermore, while cohort studies have reported conflicting results on the effects of vegetarian diets on metabolic syndromes, randomized controlled trials have reported that vegetarian diets, particularly those that include low-fat foods, improve glycemic control and result in greater weight loss compared to non-vegetarian diets.

A randomized controlled trial also reported improvements in coronary atherosclerosis associated with vegetarian diets. Conversely, most randomized controlled trials have reported lower blood pressure and low-density lipoprotein cholesterol levels, albeit accompanied by lower high-density lipoprotein cholesterol levels.

The researchers also discussed possible mechanisms explaining the association between vegetarian diets and reduced risk of many noncommunicable diseases.

They argue that while the health benefits of vegetarian diets might sometimes be specific to some diseases, often the etiopathogenetic mechanisms of many diseases are shared, and the impact of vegetarian diets in reducing the risks of such diseases occurs through more generalized mechanisms.

The low or no animal food content of vegetarian diets results in lower saturated fat intake and reduces the harmful effects of excess animal protein and heme iron.

Furthermore, the high content of fiber, polyunsaturated fatty acids, complex carbohydrates and micronutrients of plant-based diets also improves conditions such as type 2 diabetes, hypercholesterolemia and being overweight.

Consumption of whole plant foods has also been encouraged for its benefits in reducing oxidative stress and inflammation and improving insulin sensitivity and endothelial function.

Conclusions

Overall, the review covered a comprehensive set of studies comparing the impacts of vegetarian and non-vegetarian diets on general human health and on reducing the risk of many noncommunicable diseases.

Although many studies have reported that vegetarian diets have various beneficial effects on human health and are believed to reduce the incidence and mortality risks of major noncommunicable diseases, methodologies and classifications of vegetarian diets continue to be too mixed to draw conclusions definitive. about this.