29 October 2015
By Dr Wendy Winnall - PCFA Research Team
The recent announcement by the World Health Organization (WHO) that consumption of meat increases the risk of cancer has caused much debate and concern amongst the community. This finding is the conclusion of a large analysis by an international panel of experts who reviewed over 800 studies into meat consumption and cancer risk. Specifically the WHO has stated that:
- There is sufficient evidence to conclude that consumption of processed meat is a cause of colorectal (bowel) cancers,
- Fresh red meat is a probable carcinogen.
- There is strong evidence that fresh red meat contains carcinogenic substances and limited evidence that it actually causes cancer in humans.
- The association with cancer was strongest for colorectal cancers, but also notable for prostate and pancreatic cancer.
- Processed meat refers to ham, bacon, salami and similar goods, as opposed to fresh red meat that has not been processed, such as lamb, beef or pork.
It's important to recognize that the classification of processed meat as an IARC group 1 carcinogen does not mean that processed meat is as dangerous as tobacco or asbestos exposure, which are also in group 1. The classification is based on the level of evidence, not the level of risk. The evidence that processed meat causes cancer is strong, but the increased risk itself is only small. Eating meat is certainly not as dangerous as smoking or asbestos exposure. The WHO estimates that 34,000 deaths per year from cancer can be attributed to eating processed meat. Smoking, on the other hand, causes 600,000 and alcohol 200,000 deaths per year from cancer.
If meat causes cancer, should we then all become vegetarians? A vegetarian diet has many benefits, however lean meat can be part of a healthy, balanced diet. Meat is an important source of iron, zinc, vitamins and protein. The Cancer Council of Australia and the National Health and Medical Research Council’s recommend that adults can eat serves of up to 100 grams of cooked red meat, three to four times a week. They also recommend minimising processed meat, as well as including fish, whole-grains, fruit and vegetables in a balanced diet. For colorectal cancers, regular exercise, maintaining a healthy weight and avoiding smoking are also recommended to reduce the risk.
A safe level of processed meat consumption was not directly addressed by the large WHO analysis, so it’s difficult to recommend a specific safe level. One of the many studies analysed by the committee involved a large cohort of >34,000 people in Melbourne. Three or less serves of fresh red meat a week did not increase the risk of cancer in these people, however the safe level of processed meat was only 1.5 serves per week. Other studies showed a similar pattern, such as a European study involving almost 500,000 people that showed only a very low level of processed meat was safe. If you are the type of person who always has bacon for breakfast or ham sandwiches for lunch every day, this would certainly fall into the higher risk category. If this sounds like your lifestyle, then reducing the amount of processed meat you eat, or replacing it with lean meat, is recommended in order to reduce your risk of colorectal, prostate and pancreatic cancers.