Health Benefits of Vegetarian and Vegan Diets

Diets excluding animal products and their derivatives offer benefits in terms of reducing the risk of cardiometabolic diseases, cancer, and mortality associated with cardiovascular conditions. This is the finding of a study published in the journal PLOS ONE, coordinated by Dr Federica Guaraldi, endocrinologist at IRCCS - Institute of Neurological Sciences of the Bologna Local Health Authority, and Prof Davide Gori, Institute of Hygiene and Public Health, Department of Biomedical and Neuromotor Sciences, University of Bologna.

The study, focused on the review of 49 meta-analyses published between 2000 and 2023, provides an overview of current evidence, consolidating data from numerous studies conducted on this topic over the past two decades.

“We applied a rigorous research strategy, analysing a large amount of information and thus obtaining solid and precise evidence”, emphasises Prof Davide Gori. “The results are therefore a valuable resource for hypothesising preventive measures and formulating personalised dietary advice, aimed at countering the main risk factors involved in the development of cardiometabolic diseases and cancers, a highly relevant and challenging topic in public health”.

Following an "umbrella review" approach, the analysis focused on studies involving people of all ages, excluding those based on interventional studies using diets free from animal products and their derivatives as therapy for people with metabolic diseases, as well as those that included meat, fish, or poultry or their derivatives, even if in selected types and/or small quantities, to reduce data heterogeneity.

Overall, the results highlighted that vegetarian and vegan diets are significantly associated with a better lipid profile, glycaemic control, body weight, blood pressure values, and reduced inflammation markers. Additionally, a strong association was demonstrated with the reduced risk of developing ischaemic heart disease and cancer (with the most data on gastrointestinal and prostate cancers), and with reduced cardiovascular disease mortality.

At the same time, it is important to note that “No difference was found in the risk of developing gestational diabetes or hypertension in pregnant women following vegetarian diets compared to those following other dietary regimes, despite lower zinc levels and a higher risk of low birth weight infants,” adds Dr Federica Guaraldi.

Moreover, the authors highlighted the presence of limitations in interpreting the results, particularly the heterogeneity of the data (due to variability in sample sizes, demographic characteristics, and geographical origins of subjects included in the studies), as well as the type of "umbrella review," which may not have considered new or emerging associations not addressed in the reviews analysed.

Finally, the researchers pointed out that some particularly restrictive diets can lead to deficiencies in vitamins, minerals, and other nutrients and should therefore be avoided in vulnerable individuals, requiring appropriate supplementation and monitoring if necessary. Overall, caution is recommended before suggesting the widespread adoption of diets free from animal products and their derivatives until further research is completed.