Vegetarian and Vegan Diets Linked to Cancer Risk: A Comprehensive Analysis

A large-scale analysis of nearly 1.8 million individuals has revealed complex connections between vegetarian and vegan diets and the risk of developing various cancers. While generally associated with a lower risk of several major cancers, the study also identified increased risks for specific cancers within these dietary groups, highlighting the importance of nuanced dietary considerations.

Study Overview and Methodology

The international evaluation, published in the British Journal of Cancer, analyzed data from 1,645,555 meat eaters, 57,016 poultry eaters, 42,910 pescatarians, 63,147 vegetarians, and 8,849 vegans across nine cohorts in the UK, US, Taiwan, and India. [1] Researchers followed participants for a median of 16 years, tracking the incidence of 17 different cancers. [1]

Reduced Cancer Risks Associated with Plant-Based Diets

The study found that vegetarians exhibited a significantly lower risk of several cancers compared to meat eaters:

• 21% less pancreatic cancer [1]
• 12% less prostate cancer [1]
• 9% less breast cancer [1]
• 28% less kidney cancer [1]
• 31% less multiple myeloma [1]

Pescatarians also demonstrated a lower risk of breast, kidney, and colorectal cancers, while poultry eaters showed a reduced risk of prostate cancer. [1]

Increased Cancer Risks in Specific Dietary Groups

Conversely, the study identified increased cancer risks within certain dietary groups. Vegetarians had almost twice the risk of developing squamous cell carcinoma of the esophagus compared to meat eaters. [1, 2] Researchers suggest a potential link to deficiencies in certain B vitamins commonly found in meat. [1, 2]

Vegans showed a 40% increased risk of colorectal cancer compared to meat eaters. [1, 3] Scientists hypothesize this may be related to lower average calcium intake and differences in nutrient absorption. [1, 3]

Expert Perspectives and Considerations

Lead author Aurora Pérez-Cornago described the findings as “really good news” for vegetarians, noting the lower risk of several common cancers. [2] Study co-author Tim Key emphasized that the observed differences might be more directly attributable to the avoidance of meat itself rather than the adoption of a purely vegetarian diet. [2]

Researchers also cautioned that dietary habits have evolved since the study’s data collection period (1990s-2000s). [3] Modern vegan products are often fortified with calcium and other essential nutrients, potentially influencing outcomes. [3]

Key Takeaways

• Vegetarian and vegan diets are associated with a lower risk of several cancers, including pancreatic, prostate, breast, and kidney cancers.
• Vegetarians face an increased risk of esophageal squamous cell carcinoma, potentially linked to B vitamin deficiencies.
• Vegans may have a higher risk of colorectal cancer, possibly due to lower calcium intake and nutrient absorption differences.
• Dietary patterns are evolving, and modern fortified vegan products may alter these risk profiles.

Further research is needed to fully understand the complex interplay between diet, nutrient intake, and cancer risk, particularly in light of changing dietary habits and food fortification practices.

Sources:

[1] Vegetarian diets and cancer risk: pooled analysis of 1.8 … – Nature

[2] Vegetarians and cancer risk: what a study of 1.8 million people …

[3] Largest vegetarian study links lower risk of several cancers but …