Vegetarian diets may raise risks of certain cancers, groundbreaking study reveals

A new study by N.K. Shah, published in the British Journal of Cancer on 23 June 2026, challenges long-held beliefs about vegetarian diets and their link to cancer risk. The research reveals unexpected findings about how certain vegetarian eating patterns may influence the development of specific cancers. The study identified elevated risks of esophageal and colorectal cancers in some vegetarian groups. Researchers found distinct microbial imbalances in these patients, with a reduction in protective gut bacteria and an increase in pro-inflammatory species. Genetic analysis also showed changes in pathways related to cell death and DNA repair in vegetarians who developed cancer.

Dietary differences within vegetarianism played a key role. Diets high in processed plant-based foods or lacking essential micronutrients were linked to weakened mucosal barriers and heightened inflammation. Pescatarians, however, showed lower rates of these cancers compared to strict vegans, possibly due to better nutrient intake supporting mucosal defence.

The research also highlighted how high-heat cooking methods in some vegetarian cuisines can produce harmful compounds like polycyclic aromatic hydrocarbons. Genetic variants affecting folate metabolism, DNA methylation, and immune function were additionally tied to altered cancer risks in vegetarians. Shah’s work calls for updated dietary guidelines to ensure nutrient completeness in vegetarian diets. It also urges the adoption of routine cancer screening tailored to dietary habits for early detection in at-risk groups. The findings underscore the need for nuanced approaches to diet and health monitoring.