Can processed meat ever be healthy – and how much is OK to eat?

• Jill Dupleix's green pea rice with ham hock and mustard recipe

We know that cigarettes cause cancer, and as a result, they are becoming increasing difficult and expensive to buy. We know that alcohol consumption is too associated with an increased risk of developing several types of cancer, and as such there are clear guidelines on the maximum amount of alcohol the average adult should consume each week.

So, given that the World Health Organisation (WHO) has classified processed meat including ham as a group 1 (known to cause cancer) carcinogen, why are processed meats including ham, salami and bacon still sold freely in supermarkets (minus any public health warning)?

Processed meat including salami and bacon are foods that have been enjoyed in many cultures for thousands of years, and are meats that have been treated via processing techniques such as curing, fermenting, smoking or salting to extend the shelf life and add taste and texture.

Delve into the science

The key health concern relating to processed meat is that it can contain compounds called N-nitroso chemicals that can damage cells in the wall of the bowel, which can cause bowel cancer. In addition, the nitrate-based preservatives used to make processed meat also produce these same N-nitroso chemicals

It is important to remember that the amount of processed meat we eat can add up across the week.

Clare Hughes

While this science has been known for some time, and the public health position to limit the consumption of processed meat endorsed by a number of key public health organisations including Cancer Council Australia, the American Heart Association, the American Cancer Society and the Harvard School of Public Health, the question remains, if this food is so potentially dangerous for us, why does it remain freely available for human consumption?

Indeed, this is a question raised indirectly recently when a group of health researchers published a paper in the Journal of Internal Medicine, which concluded that based on a summary of current data available, there was no need for adults to reduce their current consumption of processed meat.

The review of 61 scientific studies, and over 4 million people led the investigators to conclude that the "strong anti-meat" dietary recommendations are not justified.

Health recommendations

Current recommendations are for Australians to consume no more than 455 grams of cooked lean meat each week and avoid processed meats such as ham entirely.

There are no specific recommendations for children, which leaves parents in no man's land, with many families relying on budget-friendly processed meats such as ham as cost-effective sandwich fillings.

It also fails to take into account leaner varieties of processed meat, and the newer varieties that do not contain added nitrates, and whether these are "safer" options that can be enjoyed more freely.

Clare Hughes, the nutrition unit manager from the Cancer Council, is aware that this is complicated area.

"Nitrate-free varieties of processed meat are relatively new and as such the evidence available does not distinguish between processed meat that is nitrate-free or not, so we recommend people limit their intake regardless," she says.

"It is important to remember that the amount of processed meat we eat can add up across the week. It could be a bacon and egg breakfast on weekends, then ham sandwiches for lunch as well as salami on a pizza weekly, in addition to mixed meats on weekend grazing platters. Here processed meat is being consumed on more days than not.

"Once a week on a pizza or in a cooked breakfast at the weekend is probably fine but if it's something that you're finding you are eating every day or most days during the week, it is a good idea to look for ways you can cut back and include other alternatives such as unprocessed meats, seafood, eggs, legumes and vegetables, especially if there is a family history of bowel cancer," Hughes says.

Balance is key

The other key point to consider is what other nutrient-rich foods are being consumed by the family.

Individual foods do not cause cancer in isolation, but rather dietary patterns over time. In other words, the overall nutrient balance is the most important thing when it comes to health and disease risk.

This means that a diet full of whole grains, fresh fruits and vegetables with only the occasional processed meat (once or twice each week), is much better than a diet that includes little fresh food, and a ham sandwich on white bread each day for lunch.

This may partially explain while some cultures, such as in Greece or Italy, may consume processed meats more liberally, yet do not have a greater incidence of bowel cancer that presents here in Australia.

Compare and contrast

Perhaps most importantly is an understanding of how the risk of eating processed meat regularly compares to other carcinogens such as cigarettes. It has been shown that individuals who eat 50 grams of processed meat per day have 1.18 times higher risk of developing bowel cancer than those who don't eat processed meat at all.

By comparison, the worst-case increase in risk of bowel cancer linked to eating processed meat is less than two times the risk compared to lifetime smoking, which increases the risk of developing lung cancer by 50.

This means it may simply come down to choosing the leanest processed meats you can find (free of added nitrates where possible), and enjoying it at most once or twice each week as a special breakfast addition, or on your favourite pizza, rather than your daily sandwich filler.

Susie Burrell is an accredited practising dietitian and nutritionist and holds a master in coaching psychology.