Why is processed meat causing cancer? We don't know for sure: McMaster expert

Dr. Paola Muti is aprofessor of oncology in the Michael G. DeGroote School of Medicine at McMaster University. She has some advice on how to cope with the news that processed meat has now been listed by the World Health Organization as a Group 1 carcinogen along side asbestos, alcohol and arsenic.

Here is a summary of her interview with CBC Hamilton.

What was your reaction to the decision to classify cured and processed meats in the same category asasbestos, alcohol, arsenic and tobacco?

This is the first time that a dietary item besides alcohol has been classified in this category. Finally we have an important guideline that could be translated in to procedures for cancer prevention. We are very pleased to see this happening.

Why is red meat and processed meat so bad for us?

We have been observing thousands of individualsand following them in different populations. We have seen that these two dietary components were not only risk factors for cancer but also general mortality.There have been very large studies running in Europe looking at 500,000 men and women. They observed that processed meat and red meat were associated with cancer and cardio vascular diseasemortality.The same thing happened in the United States. In small countries, in large countries there has been consistent evidence.

So why is red meat and processed meat associated with cancer? We are not sure. At McMasterwe are studying the possibility that these dietary items may actually modify the expression of genes associated with cancer development. We don't yet know for sure. There are other hypotheses related to chemicals involved in cooking meat with firewith the development ofheterocyclic amines andpolycyclic aromatic hydrocarbons or the role of salt nitrate that you can find in processed meat. There is no consensus on how this is happening but I think it is time we provide the population with reasons because these agents are actually causing cancer.

How worried should we be?

We have to make sure people are notterrorized by processed meat and red meat. Diet can represent a dangerous profile for cancer development at the same time diet could be an incredible way to prevent cancer, which is what we also study here at McMaster. We have an exciting program on cancer prevention. It is well known, in our field, that the Mediterranean diet is a strong protective factor for a number of cancers including breast cancer. There has been a lot of evidence showing the Mediterranean diet protects against cancer. Again, we don't know why this is happening. Is it related to the high vegetable content? The low content in meat? The presence of olive oil?

We need to focus on what kind of positive effect diet can have. We don't have to be dietary integralists and not eat any more sausage. We can eat a little sausage and have a good diet rich in fish and vegetables. Fish has been always associated with specific kinds of cancer protection and prevention of cardiovascular disease. We should not have any fear against dietary components.

Eating red meat or processed meat acouple of times a week would be good. Once a week would be perfect. But eat fish, too.

How should Canada changepublic policy and regulations on diet?

There should be more emphasis onsomething as dangerous as red meat and processed meat - sugars. Refined carbohydrates are really important factors in a number of cancers including breast, colon, prostate and pancreatic cancer. We can eat sugars and meat but be careful. Take it in moderation. Same thing for alcohol.

In Canada, you have berries. Berries have proven to have important protection action against cancer. Those dietary items that are good and grown here can help prevent cancer. And have fun! Cancer protection should not be terrorizing. Cancer protection is fun. It leads to a good quality of life, a good diet and a happy life.