Giving up meat may reduce the risk of some types of cancer, but a large study suggests it may be linked to an increased risk of colon cancer – especially in vegans.
This debate comes more than a decade after the World Health Organization classified processed meats as Group 1 carcinogens, in the same evidence category as tobacco and alcohol.
Studies have shown that consuming about 50 grams of processed meat per day (e.g. bacon) can increase the risk of colorectal cancer by about 20%.
What did the new study reveal?
Researchers from the University of Oxford analyzed the risk of 17 types of cancer in five dietary groups: meat eaters, moderate meat eaters, fish eaters (pescatarians), vegetarians, and vegans.
The analysis included over 1.8 million people from Britain, the US, Taiwan and India, followed for an average of 16 years. During this time, over 220 cases of cancer were recorded.
The results showed that vegetarians had a lower risk of:
pancreatic cancer
breast cancer
prostate cancer
kidney cancer
multiple myeloma (blood cancer)
However, an increased risk of colon cancer was observed. Vegans had about a 40% higher risk compared to meat-eaters. Vegetarians also had almost twice the risk of esophageal cancer (squamous type).
The study was published in the British Journal of Cancer.
Why is this result unexpected?
In theory, vegan diets are higher in fiber and lower in saturated fat – factors commonly considered protective against colon cancer.
One possible explanation is that the meat eaters in the study consumed very little meat – less than the British average. If heavy consumers of processed meat had been included, the results might have been different.
Another possible factor is calcium. Vegans in the study had the lowest calcium intake, an element that has been linked to protection against colorectal cancer. Although they had higher fiber intake and less alcohol, a lack of calcium may have played a role.
What do the experts say?
Prof. Tim Key from Oxford stressed that the results do not contradict existing evidence on the risks of processed meat. He pointed out that most of the meat-eaters in the study were relatively conservative in their lifestyles.
Independent experts, including researchers from King's College London and the University of Aberdeen, urged caution in interpretation, noting that the study is observational and does not prove cause and effect. Also, vegetarian diets vary widely between individuals - they are defined by what is excluded, not necessarily the quality of what is consumed.
General overview
Overall, the picture for vegetarians looks positive, with reduced risks for several important cancers, including prostate and kidney. The lower risk for blood cancer may be linked to a healthier body weight, as obesity is a major risk factor.
However, the findings show that eliminating meat is not automatically risk-free. People following vegan or vegetarian diets should ensure adequate intake of calcium, vitamin B12, zinc and other micronutrients – through fortified foods or supplements.
Cancer remains one of the leading causes of death globally, and colon cancer is among the few that is increasing significantly in people under 50. Such studies show that the relationship between diet and cancer is complex – and requires a balanced approach, not extremes. /GazetaExpress/
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