IARC Report: Red Meat, Processed Meat and Cancer
What is the IARC and what do they do?
IARC is the
International Agency for Research on Cancer and it is an agency of the World
Health Organization, (WHO) that looks at substances and other environmental
factors which pose a risk of cancer in humans e.g. chemicals, lifestyle
factors. They do this by asking a panel of experts to evaluate the balance of
evidence in the scientific data concerning a particular environmental factor
and the risk of cancer. On the 26th October 2015 they published the
results of their evaluation of the risk of developing cancer from the
consumption of red meat and processed meat.
What is red meat?
The IARC report refers to red meat as all
mammalian muscle meat, including, beef, veal, pork, lamb, mutton, horse, and
goat. It does not include poultry and fish.
What is processed meat?
report refers to processed meat as meat that has been transformed through
salting, curing, fermentation, smoking, or other processes to enhance flavour
or improve preservation e.g. hot dogs (frankfurters), ham, sausages, bacon and
What is a carcinogen?
is a substance that has been associated with cancer in humans.
What does the IARC classification system for
classifies carcinogens into five categories as follows:
Carcinogenic to humans
Probably carcinogenic to humans
Possibly carcinogenic to humans
Not classifiable as to its carcinogenicity
Probably not carcinogenic to humans
It is important to understand that this classification system
indicates the weight of the evidence as to whether an agent is capable of
causing cancer. It does not measure the likelihood that cancer will occur as a
result of exposure (i.e. the level of risk) so it is not an indication of how
potent the agent is as a carcinogen.
Red meat was classified as Group 2A “probably
carcinogenic to humans”. What does this mean exactly?
In the case
of red meat, the classification is based on limited evidence from
epidemiological studies (studies
involving observations of cancer rates in different groups of people eating
different diets) showing positive associations between eating red meat and
developing colorectal cancer as well as strong mechanistic evidence (reasons for how red meat might cause cancer)
Processed meat was classified as Group 1, “carcinogenic
to humans”. What does this mean?
is used when there is sufficient evidence of carcinogenicity in humans. In
other words, there is convincing evidence that the agent causes cancer. The
evaluation is usually based on epidemiological studies showing the development
of cancer in exposed humans.
What types of cancer is linked to red meat
consumption and how could it happen?
strongest, but still limited, evidence for an association with eating red meat
is for colorectal cancer. This is cancer of the colon and/or rectum which are
both parts of the bowel.
compounds in red meat like haemoglobin that can trigger production of N-nitroso compounds during digestion and
these chemicals can be carcinogenic. Also cooking red meat at high temperature
(grilling, frying, roasting, barbequing) can also lead to the formation of
chemicals that can be carcinogenic e.g. polycyclic aromatic hydrocarbons.
Should I cook my red meat less?
It is important
to cook red meat thoroughly to an internal temperature of at least 75oC
to kill harmful bacteria. The exceptions to this are whole, untenderised cuts
of beef or lamb e.g. steaks, which can be cooked to preference. However, the
less browned or burned the outside of the meat is, the fewer carcinogenic
chemicals are formed.
What types of cancer is linked to processed meat
concluded that eating processed meat causes colorectal cancer. An association
with stomach cancer was also seen, but the evidence is not conclusive. The consumption of processed meat was
associated with small increases in the risk of cancer in the studies reviewed.
similar compounds in processed meats as red meats that may cause cancer (see Q. What types of cancer is linked to
red meat consumption and how could it happen?) processed meats may also
contain other chemicals as a result of their processing/preservation that may
be associated with cancer e.g. nitrites in cured meats.
Is there any cancer risk associated with poultry or
No, there is no cancer risk associated with poultry or fish
intake. Poultry has much lower amounts
of haemoglobin and does not trigger the production of N-nitroso compounds in the body.
This may explain the lack of cancer association with poultry
In many studies,
fish intake appears to be protective against cancer. This may be due to some extent to the
protective effects of fish oils; however some protective effects have been seen
in white fish.
Should I avoid red meat altogether?
No. Lean red meat1
consumed in moderation can be a valuable part of a healthy diet as it is a good
source of protein and a particularly good source of absorbable iron.
should avoid consuming large quantities of red meat, especially processed meat
(high in fat and salt)
What is moderation?
Healthy eating is all
about ‘moderation’ which means avoiding large portion-sizes and frequent
consumption (i.e. be careful on how much red meat you eat at any one time and
how often you eat it). The amount of red meat you need in a day relates to your
body size and an easy way to estimate this is to choose a portion that is the
same size as the palm of your hand without your fingers and thumb. On average this is approximately 100g (4oz).
alternatives to meat – such as fish (protective against colon cancer), poultry
(no effect on colon cancer or beans/lentils (vegetarian protein foods that
provide fibre that protects against colon cancer) so that you only choose red
meat as a main meal three days a week.
This keeps red meat intake to 300g per week, which is an amount previous
reports have indicated is best.
detailed information on the best food choices from the ‘Meat, poultry, fish and
alternatives food group’ - see pages 10 and 11 in Healthy Eating
and Active Living for Adults, Teenagers and Children over 5 Years developed by the Food Safety
Authority of Ireland, in collaboration with the Department of Health, SafeFood
and the Health Service Executive.
What should I eat to prevent cancer?
Cancer is a complex disease and can be caused
by a number of factors including genetics, smoking and other environmental
factors. However, healthy eating can
play an important role in the prevention of cancer. Here is some of the best advice for healthy
living to prevent cancer:
- Be a healthy weight
- Be active
- Avoid alcohol
- Eat plenty of fruit &
- Choose different types of fruit
- Choose wholegrain breads and
- Avoid excess fats and oils
1Lean beef, pork, lamb
the size and thickness of the palm of your hand (without fingers and thumb)
shows how much meat, poultry or fish you need in a day. Most of this can be
used for your main meal, with the remainder (if you want) used for your light
Last reviewed: 31/5/2017