Study Finds Vegans Have Higher Colon Cancer Risk

A comprehensive study analyzing data from over 1.8 million people suggests that while vegetarian diets may lower the risk of several cancers, vegans face a roughly 40% increased risk of developing colon cancer compared to meat-eaters [1]. Published in the British Journal of Cancer, the research tracked participants for an average of 16 years across the US, UK, India, and Taiwan to examine the links between dietary patterns and 17 different cancer types [1].

Key takeaways

• Vegans in the study had a roughly 40% higher risk of colon cancer, potentially linked to lower calcium intake [1].
• Vegetarians showed a lower risk of five cancers, including breast and prostate cancer, compared to meat-eaters [1].
• Vegetarians had nearly double the risk of esophageal cancer, possibly due to low riboflavin levels [1].
• The study is observational and relies on older data, which may not reflect modern fortified diets [1].

Potential nutrient gaps drive specific cancer risks

The study found that vegetarians had a significantly lower risk of developing five specific cancers: multiple myeloma (31% lower), kidney cancer (28% lower), pancreatic cancer (21% lower), prostate cancer (12% lower), and breast cancer (9% lower) [1]. However, the data also revealed potential downsides to excluding animal products. Vegans in the study exhibited a roughly 40% increased risk of colon cancer, a finding researchers attributed to potential calcium deficiencies [1]. Calcium helps bind to free fatty acids in the gut, and investigators noted that average calcium intake was quite low among the vegan participants [1]. Additionally, vegetarians faced almost double the risk of squamous cell carcinoma of the esophagus compared to meat-eaters, which investigators suggested might be related to insufficient riboflavin intake [1].

Data limitations and modern diet changes

Experts caution that the study's findings are observational and do not prove that specific diets directly cause changes in cancer risk [1]. Furthermore, the data may not reflect current nutritional realities, as participants were recruited at least 10 years ago, with some cohorts dating back to the 1980s [1]. Nutrition scientist Nerys Astbury noted that while past vegetarian diets were often based on whole foods like vegetables and pulses, modern versions frequently include highly processed meat and dairy alternatives [1]. Epidemiologist Tim Key added that recent data indicates calcium intake differences between vegans