We analyse global research on how methods of preservation and processing of foods affect the risk of developing cancer.
There is strong evidence that consuming:
For processed meat, Cantonese-style salted fish and foods preserved by salting, the evidence shows that, in general, the more people consume, the higher the risk of some cancers.
– This is the opinion of our Expert Panel
A global recommendation about consumption of Cantonese-style salted fish has not been made, as this type of fish is consumed only in specific parts of the world. Nevertheless, the Panel advises that it’s best not to consume Cantonese-style salted fish.
A global recommendation about consumption of foods preserved by salting has not been made as these types of food are mostly consumed only in Asia. Nevertheless, the Panel advises that it’s best not to consume foods preserved by salting.
There is also other evidence on preservation and processing of foods that is limited (either in amount or by methodological flaws), but is suggestive of an increased risk of some cancers. Further research is required, and the Panel has not used this evidence to make recommendations. For more information download the full report.
Foods can be preserved and processed in a number of ways prior to consumption. These different methods affect the chemical composition of foods as well as their nutritional value and carcinogenic potential.
Processed meat generally refers to meats (usually red meats) that have been preserved by salting, curing, fermentation, smoking, or other processes to enhance flavour or improve preservation. Examples of processed meat include ham, salami, bacon, pastrami and some sausages. These include sausages, bratwursts, chorizo, frankfurters and ‘hot dogs’ to which nitrites or nitrates or other preservatives are added.
Salting is a traditional method of preserving raw fish throughout much of the world. Depending on the precise conditions, salt-preserved fish may also undergo fermentation.
Cantonese-style salted fish is characterised by using less salt and a higher degree of fermentation during the drying process than fish preserved (or salted) by other means, because of the relatively high outdoor temperature and moisture levels.
Although the use of salt as a preservative has generally decreased as industrial and domestic use of refrigeration has increased, some traditional diets still include substantial amounts of salt-preserved foods, including salted meat, fish, vegetables and sometimes also fruit. The requirement for salt for human health has been estimated to be much lower than amounts currently consumed. World Health Organization pragmatically recommends restricting average salt consumption for populations to less than 5 grams per day (equivalent to less than 2 grams of sodium per day).
This section covers the primary hypotheses and is not based on a systematic or exhaustive search of the literature.
In 2018, we produced the Diet and Cancer Report, the third in our series of major reports looking at the many ways in which our diets, and how active we are, affect our cancer risk. You can find out much more about preservation and processing of food and the risk of cancer by downloading a pdf of the relevant chapter in the 2018 report. Please note, however, that this webpage may have been updated since the report was published.