Landmark Study Reveals Vegetarian Diets Reduce Some Cancer Risks But Increase Others by 93

A landmark study has revealed that vegetarian and vegan diets may offer protection against several types of cancer, but they also appear to significantly increase the risk of others. The research, conducted on over 1.8 million people, marks the largest analysis to date on the relationship between diet and cancer risk. Experts have called the findings both groundbreaking and complex, emphasizing that while vegetarian diets can lower the risk of certain cancers, they are not without their own potential dangers.

The study found that vegetarians were up to 31% less likely to develop pancreatic, prostate, breast, kidney, and multiple myeloma cancers compared to meat-eaters. Combined, these cancers account for around a fifth of cancer deaths in the UK. However, vegetarians had a 93% higher risk of developing the most common type of esophageal cancer, while vegans faced a significantly increased risk of bowel cancer. These results have sparked a debate among health professionals about the nuances of diet and cancer prevention.

"Dietary patterns that prioritise fruit, vegetables and fibre-containing foods, and avoid processed meat, are recommended to reduce cancer risk," said Professor Tim Key, a co-author of the study from the University of Oxford. "Our study helps to shed light on both the benefits and risks associated with vegetarian diets." Yet, some experts, like Professor Jules Griffin from the University of Aberdeen, have raised concerns. He argued that the study fails to compare vegetarian diets with an "optimum diet for reducing risk," where fish and meat are consumed in moderation.

Oesophageal cancer, the most common type of which saw a nearly doubled risk among vegetarians, is a particularly concerning finding. The disease, which affects the food pipe, can cause symptoms such as difficulty swallowing and unexplained weight loss. Around 9,000 people are diagnosed with oesophageal cancer annually in the UK, though rates are far higher in parts of Asia. Researchers suggest that essential nutrients in red meat, such as iron, zinc, and B vitamins, may play a protective role, though the exact mechanism remains unclear.

Bowel cancer, another major concern, saw vegans face a 40% higher risk than meat-eaters. The study highlights the importance of calcium in reducing bowel cancer risk, noting that a daily glass of milk can slash the risk by nearly a fifth. Dr. Shireen Kassam, a consultant haematologist at King's College Hospital, emphasized that well-planned vegan diets can meet calcium needs but warned that not all vegan diets are nutritionally balanced. "This is not a simple story of veganism increasing cancer risk," she said. "It's a reminder that all diets must be nutritionally well designed."

The study also found that vegetarians had a 21% lower risk of pancreatic cancer, one of the deadliest cancers, and a 9% lower risk of breast cancer in women and a 12% lower risk in men for prostate cancer. These findings align with previous research linking processed meats to higher cancer risks. However, the study noted that meat-eaters in the research consumed far less meat than the general population, complicating the interpretation of the results.

The researchers concluded that the relationship between diet and cancer is complex and varies by cancer type. They called for further research to determine whether the benefits of vegetarian diets are due to the exclusion of meat or the inclusion of plant-based foods. As public health experts continue to analyze these findings, the study underscores the need for personalized dietary advice and the importance of a balanced approach to nutrition for cancer prevention.