The World Health Organization has declared that by eating processed meat like ham or sausages you could be turning yourself into a candidate for getting cancer. They also said that unprocessed red meat may present the same risk. So should you stay away from meat?
What exactly qualifies as processed meat?
Processed meat is defined as meat from any origin that is salted, smoked or cured to enhance its flavour or to extend the shelf-life of the meat. Such processed meats commonly contain beef, pork or even poultry. 
How do red meat and processed meat cause cancer?
Convincing evidence suggests that individuals who follow a diet high in red and processed meat have a greater risk of developing cancer.
Several theories exist that could explain the process through which processed meat and red meat cause cancer; especially colorectal cancer, prostate cancer and pancreatic cancer.
In red meat, you may find excess protein, excess fat, too much iron and heat-induced mutagens. The same factors may also be responsible for carcinogenesis in processed meat along with salt and nitrites that are added in the curing process. There may be even more factors that could contribute to carcinogenesis, but they have not been researched effectively.
What we eat may have an effect on our cellular processes that may lead to the accumulation of some of the hallmarks of cancer. 
High fat and protein content of food
Obesity is another possible culprit in the process of carcinogenesis as it has been associated with a higher risk for getting cancer. Fatty diets and calorie-rich diets may lead to obesity which causes insulin resistance and changes in blood values that are associated with obesity.
The circulating factors are then responsible for increasing proliferation and decreasing apoptosis (cell death) of precancerous cells and therefore also for promoting tumour growth.
Other mechanisms that connect adiposity to cancer risk are hyperinsulinemia, alteration of the metabolism of sex hormones, upregulation of growth factors, chronic inflammation, oxidative stress, changes in immune function and an altered production of vascular growth factors and adipokines by adipose (fat) tissue.
Furthermore, studies have suggested that the carcinogenic process can be supressed with calorie restriction. 
Some carcinogens are formed in meat when it is cooked for a long time on high heat or if it is exposed directly to a flame (this can also be true for other foods) like when it is barbequed or fried for extended time periods. 
High salt intake
Sodium chloride is a well-known preservative that is used to enhance the safety of processed foods and to extend their shelf life. Some scientific experiments are suggesting that salt intake may assist the colonisation of Helicobacter Pylori (a disposing factor for the development of stomach cancer) that causes mucosal damage. [3
Lifestyle recommendations to prevent cancer
A cancer prevention strategy was drawn up by experts based on nutrition-related factors that were connected to cancer risk. According to the strategy a healthy diet that may help to prevent cancer is one that:
- Allows people to be as lean as they can possibly be without being underweight
- Is rich in vegetables, fruits, pulses and whole grains
- Contains red meat in small amounts
- Contains no processed meats
- Has low salt intake
How much red meat or processed meat is safe to eat?
It has been suggested that red meat consumption should be limited to around 500g per week and cured meats should be avoided where possible, especially if they are high in salt or fat. You should, however, try to stay away from processed meat at all times as a direct link between processed meat and cancer has been found by research experts. 
Should you stop eating meat?
The latest research certainly supports that a high intake of red meats and processed meats may place you in a higher risk category for certain cancers.
However, we need to realise that meat is also an essential source of certain nutrients, some of which may possess potential anti-cancer properties. Meat is a source of Zinc, vitamin B6, vitamin B12, vitamin, calcium, folate and selenium.
Some possible approaches may allow for the consumption of small amounts of meat to ensure that you get the needed nutrients and lower your risk of getting cancer.
- Petroff A. Processed meat causes cancer, says WHO. October 2015; [Available from: http://money.cnn.com/2015/10/26/news/red-meat-processed-cancer-world-health-organization/index.html.]
- Norat T, Scoccianti C, Boutron-Ruault MC, Anderson A, Berrino Fet al. European Code against Cancer 4th Edition: diet and cancer. Cancer epidemiology. December 2015; vol. 39: S56-66.
- Corpet D. Red meat and colon cancer: should we become vegetarians, or can we make meat safer? Meat Sci. 2011; vol. 89 (3): 310-6.
- McCullough ML, Gapstur SM, Shah R, Jacobs EJ, Campbell PT. Association between red and processed meat intake and mortality among colorectal cancer survivors. Journal of Clinical Oncology. July 2013; JCO-2013.
- Ferguson LR. Meat and cancer. Meat Science. 2010; vol. 84: 308–313.