Protein is good for your health in many different ways. Your body needs protein to grow cells, heal tissue and maintain a healthy immune system. This will help you recover more quickly and avoid infection. Sources of protein include meat, fish, poultry, milk and alternatives, nuts, dried beans, peas and lentils, and soy products. Meat is a valuable source of several other nutrients including iron, zinc and vitamin B12.
- White meat is lighter coloured meat that comes from poultry, such as the breasts of chicken and turkey.
- Red meats include beef, lamb, goat, pork and veal.
- Processed meat generally refers to meats preserved by curing, smoking or salting, or by the addition of preservatives.
Red and processed meat and cancer
Research shows that a diet high in red meat and eating processed meat increases the risk of colorectal cancer. The reasons why red and processed meat increase the risk of colorectal cancer are currently being studied. Some possibilities include:
Cooking temperature – cooking meat at high temperatures until very well done produces chemicals called heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs). HCAs and PAHs may increase cancer risk.
Chemicals that are formed when the meat is digested or processed – nitrates and nitrites are added as a preservative in processed meats. Nitrates are converted to nitrites in the stomach. Nitrites may contribute to the formation of potentially cancer-causing N-nitroso compounds such as nitrosamines and nitrosamides. Several N-nitroso compounds are thought to cause cancer.
Dietary heme iron – red meat contains higher amounts of heme iron than white meat. Heme iron has been shown to cause damage to the mucosa of the colon and promoted increased cell growth in animal studies. It also promotes the formation of potentially cancer-causing N-nitroso compounds.
An increased intake of red and processed meat appears to modestly increase the risk of death from cancer, heart disease and other diseases.
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Studies have shown that eating a lot of well-done meat cooked at high temperatures may increase the risk of cancer. High-temperature cooking methods include frying, broiling and barbequing. Cooking meat, poultry and fish at high temperatures creates chemicals called heterocyclic amines (HCAs). Researchers have found over a dozen different HCAs in cooked meat that may increase cancer risk.
When fat from meat, poultry or fish drips onto hot coals or stones, other potentially cancer-causing substances are formed. Polycyclic aromatic hydrocarbons (PAHs) are added onto food by smoke and flare-ups.
Factors that may be linked to the creation of HCAs and PAHs include:
- type of food cooked
- Meat cooked at high temperatures has the most HCAs.
- Other foods with protein, such as eggs, tofu and organ meats like liver, have very little or no HCAs when cooked.
- Gravy made from meat drippings contains large amounts of HCAs.
- cooking temperature
- Frying, broiling and barbecuing at a high temperature create the largest amounts of HCAs.
- Oven roasting and baking are done at lower temperatures, so lower levels of HCAs are likely to form.
- Boiling, poaching and stewing are done at even lower temperatures, so very low levels of HCAs are created.
- cooking time
- Foods cooked a long time until they are well done can contain HCAs and PAHs.
- Meat that is more well done contains higher levels of HCAs and PAHs than meat than is less well done.
The highest daily intake of HCAs that a person can safely eat has not been established. There is also no good way to measure how much HCAs would have to be eaten to increase cancer risk. More research is needed.
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How much meat?
Canada’s Food Guide recommends that adults have 2 to 3 servings each day from the meat and alternatives food group. Based on recent evidence, adults should try to limit the amount of red meat to 3 servings per week. The recommended number of servings per day may differ depending on your age, sex and how active you are.
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Reducing your risk
The recommended amount of meat prepared in a healthy way is part of healthy eating.
- One serving of meat, fish or poultry is roughly 85 grams (3 ounces) when cooked – this is smaller than a deck of cards.
- Choose poultry or fish more often. Make up the rest of your meal with vegetables and healthy grains.
- Eat more alternatives to meat. When making a chili or stew, cut the meat quantity in half and replace it with double the quantity of beans or other legumes.
- Make meats go further by chopping them into small pieces or buying them ground and using smaller amounts in stir fries, salads and pasta sauces.
- Make at least one supper a week meat-less.
- Trim off visible fat from meat. Remove skin from poultry. This will reduce the amount of harmful chemicals that are created from burning fat.
- When barbequing, choose lean cuts of meats, poultry and seafood over higher fat meats. This will reduce the amount of harmful chemicals from the smoke created by burning fat.
- Barbecue slowly and keep the food away from the hot coals so that flames are less likely to engulf the food to prevent charring.
- Cook meat, fish, seafood and poultry at lower temperatures by braising, stewing, steaming or roasting more often.
- Use high temperature cooking methods such as barbecuing, pan frying and broiling less often.
- Thaw and partially cook meat in the microwave before cooking to lower the levels of HCAs. Pour off any liquid formed during microwaving to further help reduce HCA levels. Avoid making gravy from meat drippings.
- Marinate meat, poultry and fish before cooking. Studies have shown that marinating these foods can prevent the formation of cancer-causing chemicals. Use an oil-free marinade that contains a strong acid like lemon juice or balsamic vinegar.
- Try grilling vegetables, veggie burgers and fruit slices. Most experts agree that plant-based foods do not form the cancer-causing substances when cooked at high heat.
- Save processed meat for special occasions, such as ham for a holiday dinner or a hot dog at a sporting event.
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