Vegetarian diet linked to lower cancer risk – and hidden dangers

New global research reveals complex links between diet types and cancer risks, including surprising findings for vegetarians and vegans

In Short

• Vegetarians have lower risks of breast, prostate, pancreatic, kidney and multiple myeloma cancers
• Vegans face higher risk of colorectal cancer than meat-eaters
• Poultry eaters have lower prostate cancer risk than meat-eaters.

The largest global study so far examining the link between diet type and cancer risk shows that, compared to meat-eaters, vegetarians have lower risks of five malignancies – breast, prostate, pancreatic, kidney and multiple myeloma – but, surprisingly, a higher risk of a common type of oesophageal cancer.

Vegans- who consume no poultry or dairy products- were also found, in this landmark study analysing dietary patterns of over 1.8 million people across four countries including India over many years, to have a higher risk of developing colorectal cancer.

The findings, based on participants in the UK, US, India and Taiwan followed for an average of 16 years and published recently in the British Journal of Cancer recently, also show that poultry eaters had a lower risk of prostate cancer compared to meat-eaters, while pescatarians had lower risks of colorectal, breast and kidney cancers.

Pescatarians are those who consume fish and seafood but no other meat.

The analysis, funded by the World Cancer Research Fund, examined links between diet and 17 cancers, including those of the gastrointestinal tract, lung, reproductive system, urinary tract and blood.

Based on the findings, researchers note that vegetarian diets may influence cancer risk in multiple ways, and that the results should be interpreted with caution.

“The study largely highlights the benefits of a diet rich in fruits and vegetables, showing it can be protective against several cancers,” Dr K M Venkat Narayan, professor and diabetes and metabolic disease researcher at Emory University, US, and a co-author of the study, told India Today.

STRIKING FINDINGS

The researchers analysed data from about 1.64 million meat-eaters, 57,016 poultry eaters (who avoided red meat), 42,910 pescatarians, 63,147 vegetarians and 8,849 vegans, all followed for an average of 16 years.

Factors that could influence cancer risk, such as body mass index (BMI) and smoking, were accounted for.

The findings showed that vegetarians had a 21 percent lower risk of pancreatic cancer, 12 percent lower risk of prostate cancer and 9 percent lower risk of breast cancer compared to meat-eaters.

They also had a 28 percent lower risk of kidney cancer and a 31 percent lower risk of multiple myeloma, a cancer of plasma cells.

However, while a vegetarian diet appeared protective overall, researchers also found that vegetarians had nearly double the risk of the most common type of oesophageal cancer – squamous cell carcinoma – compared to meat-eaters.

Vegans, on the other hand, were found to have a 40 percent higher risk of colorectal cancer than meat-eaters.

Dr Narayan described these as “surprising findings.”

Researchers suggested that the higher risk of oesophageal cancer among vegetarians could be linked to deficiencies in key nutrients such as B vitamins, while the increased colorectal cancer risk in vegans may be associated with lower calcium intake and other nutritional gaps.

However, scientists emphasised that more research is needed to determine whether meat consumption itself is problematic, or whether specific aspects of vegetarian diets contribute to reduced cancer risk.

INDIA’S DATA

The study is part of the Cancer Risk in Vegetarians Consortium – the largest investigation to date on this subject – comprising nine cohorts across three continents with diverse dietary patterns and a large number of cancer cases.

Dr Nikhil Tandon, head of the Department of Endocrinology and Metabolism at AIIMS, Delhi, who played a key role in analysing Indian data, explained that the country’s contribution came from a cohort of about 10,000 participants under the Centre for Cardiometabolic Risk Reduction in South Asia (CARRS), spanning two cities.

He noted that this community-based cohort from Delhi and Chennai has generated extensive data since before 2010, including lifestyle patterns, dietary details, biological and genetic markers, and disease profiles through annual surveys.

Dr Tandon said the findings are nuanced and should be viewed in context. While dietary habits in Western countries are often shaped by individual choice, in India they are frequently influenced by generational practices.

In the paper, authors also conclude that although dietary choices significantly affect cancer patterns, individual findings must be interpreted in light of regional dietary variations.

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