Processed meat causes cancer Credit: Flickr/CC BY-SA 2.0
This post was first published in 2019, but has been reviewed and updated in March 2021.
It’s not new news that processed and red meat are linked to bowel cancer. But in 2019, Cancer Research UK scientists took a closer look at how much meat might be enough to increase bowel cancer risk.
The study, published in the International Journal of Epidemiology, looked at whether people who eat an average of 76 grams of processed and red meat a day – approximately 3 slices of ham – are still at increased risk of bowel cancer. This is similar to the average amount people in the UK eat each day, and falls in a somewhat grey area within government guidelines – which state anyone who eats more than 90 grams a day should cut this to no more than 70 grams a day.
The main takeaway from the study was that even moderate meat-eating increases bowel cancer risk. So, what does this mean for a nation famed for its fry ups?
What are ‘red’ and ‘processed’ meat?
First, let’s clear up some definitions.
‘Red’ meat is (as you might expect), any meat that’s a dark red colour before it’s cooked – this obviously means meats like beef and lamb, but also includes pork.
‘Processed’ meat is meat that’s not sold fresh, but instead has been cured, salted, smoked, or otherwise preserved in some way (so things like bacon, sausages, hot dogs, ham, salami, and pepperoni). But this doesn’t include fresh burgers or mince.
Both of these types of meat are distinct from ‘white’ meats, like fresh chicken or turkey, and fish (neither of which appear to increase your risk of cancer).
How do we know processed and red meat cause cancer?
The evidence linking processed and red meat to cancer has been stacking up for over a decade. And in 2015, the International Agency for Research on Cancer (IARC) – a group of experts that review and report on research evidence – classified processed meat as a ‘definite’ cause of cancer (or Group 1 carcinogen) – the same group that includes smoking and alcohol. And red meat is a ‘probable’ cause of cancer (or a Group 2a carcinogen) – the same group as night shift work.
While this may sound alarming, it’s important to remember that these groups show how confident IARC is that red and processed meat cause cancer, not how many cancer cases they cause, as we wrote when we covered a previous IARC decision on diesel emissions, and interviewed one of our experts in the causes of cancer.
As Professor David Phillips – a Cancer Research UK-funded carcinogen expert from King’s College London – explains, “IARC does ‘hazard identification’, not ‘risk assessment’.
“That sounds quite technical, but what it means is that IARC isn’t in the business of telling us how potent something is in causing cancer – only whether it does so or not”, he says.
To take an analogy, think of banana skins. They definitely can cause accidents, explains Phillips, but in practice this doesn’t happen very often (unless you work in a banana factory). And the sort of harm you can come to from slipping on a banana skin isn’t generally as severe as, say, being in a car accident.
But under a hazard identification system like IARC’s, ‘banana skins’ and ‘cars’ would come under the same category – they both definitely do cause accidents.
To put things in perspective, let’s look at how processed meat stacks up against smoking.
How does processed and red meat cause cancer?
So far, research has linked 3 chemicals to increased bowel cancer risk. These chemicals are either naturally found in meat, added during processing or produced when cooking:
- haem (a red pigment found mostly in red meat);
- nitrates and nitrites (used to keep processed meat fresher for longer); and
- heterocyclic amines and polycyclic amines (produced when meat is cooked at high temperatures)
All 3 can damage the cells in our bowel, and it’s the accumulation of this damage over time that increases cancer risk.
How much matters?
The latest study analysed data from half a million UK adults over almost 7 years and found that moderate processed and red meat eaters – those eating 79g per day on average – had a 32% increased risk of bowel cancer compared to people eating less than 11g of red and processed meat daily.
To put this in context, for every 10,000 people on the study who ate less than 11 grams of red and processed meat a day, 45 were diagnosed with bowel cancer. Eating 79 grams of red and processed meat a day caused 14 extra cases of bowel cancer per 10,000 people. These figures are just for the independent effect of meat consumption, as they take into account other differences between these groups of people, for example sex, deprivation, smoking, physical activity, alcohol intake, other aspects of diet, reproductive factors, and body mass index.
Professor Tim Key, who co-led the recent study and is deputy director at the University of Oxford’s cancer epidemiology unit, says that while the impact of cutting back on processed meat might be smaller than quitting smoking, it’s still important.
“Everyone eats and everyone is at risk of colorectal cancer,” he says. “So any increase in risk makes a difference when we look at the whole population.”
And he sees the results as a reminder for those following government guidelines.
“Current government guidelines suggest if you eat more than 90 grams a day on average you should cut down to 70 grams a day. Our results suggest cutting down a bit more gives slightly lower risk, and are a reminder that there is still an increase in risk for modest intakes of meat.”
Top tips for cutting down
- Pay attention to your portions – try having 1 sausage instead of 2 or switching half of the meat in your usual dishes for beans or veggies.
- Have meat free days – pick a day (or days) to have no meat at all.
- Get out of a recipe rut – look for new recipes that use fresh chicken or fish instead of processed and red meat.
What if I have my bacon sandwich on wholemeal bread?
Having a diet high in fibre, especially wholegrains, found in foods like wholemeal bread or brown rice, and doing lots of physical activity can is associated with lower risk of bowel cancer – so could this mitigate cell damage from eating processed and red meat?
Both fibre and lots of physical activity help us to poo more often, reducing the amount of time harmful chemicals, including those in processed and red meat, spend in the gut. But so far it’s not clear how much difference this could make to the amount of damage in our cells.
Unfortunately, it’s not as simple as balancing out something that increases risk with something that reduces it. Studies take in to account other things that might impact risk, so good studies that show the link between processed and red meat and bowel cancer will note fibre intake and many other factors which can be associated with both cancer risk and meat intake.
What does this mean for me?
The evidence is clear that eating less processed and red meat can help reduce the risk of bowel cancer, the 4th most common cancer in the UK.
Eating less can make a difference, but it’s important to think about doing this as part of a healthy diet overall, along with being active.
“The most important diet related risk factors for cancer are obesity and alcohol, which both increase risk of many types of cancer, and cause more cases than red and processed meat,” says Key.
And he notes that diet has other health impacts beyond bowel cancer risk.
“For example, meat can be an important source of iron so if someone is thinking about giving up meat all together they need to think about other sources of this,” he says.
So, although this evidence doesn’t suggest we need to ditch processed and red meat altogether, it does serve as a reminder to think about how much we’re eating, and how often.
Katie Patrick is a health information officer at Cancer Research UK
Maria Hulburd March 9, 2023
Fantastic source of vital information provided by studies. Love receiving this detail & has totally changed my attitudes to food consumption after a lifetime of dieting & having a gastric bypass 13 years ago. My family members (female siblings, parents, aunts, uncles & grandparents) have unfortunately inherited several different cancers ranging from pancreatic, colorectal, to lymphoma & breast cancer.
Sandra Barker March 1, 2023
C Jay August 26, 2021
We need to do better research than this. What other foods are nitrates and nitrites added to? Which have the most? Why are safe alternatives not used? Why are known carcinogenic additives allowed in food?
Debbie August 13, 2021
I believe there are other food factors which are being played down . Hormones in milk and cheese and eggs, BPA in plastics leaching Into food, pesticides in fruit and veg. I have had breast.cancer but with so many causes including pollution, genetics etc etc etc how will we ever know what caused our cancer as we are fed information by media what aren’t they really telling us and how many more people will die before we find the real truth. I believe everything which contributes to cancer should be made safer not just blaming us on what we eat when we trust food agencies to feed us healthy foodstuffs.
Lyn April 27, 2021
Then why has Dr told grandson he must eat plenty of red meat
L K April 18, 2021
My husband drink like fish and smoke like lum. He eat ham and bacon everyday for his sandwiches. He is a tea drinker with at least 8 – 10 cups a day with teaspoon of sugar each cup. He eat ice cream and chocolate every night. Generally he is healthy. I don’t smoke, drink occasionally, I don’t have sweet tooth and no sugar with my tea and coffee. I eat meat once or 2x a week and I was recently diagnosed with breast cancer. What a joke!!!
Helen Mullineux April 11, 2021
Very interesting. I wish I have heard this sooner – I have had bowel cancer though I don’t smoke and haven’t had alcohol for 5 years. I am now having chemotherapy to prevent the cancer’s return. I have also had bladder cancer and do not know the causes of that.
Catherine April 11, 2021
Fantastic news very informative positive out look
Patrick Wynne-Jones April 10, 2021
A most useful analysis and guidelines. Will inform my future meat-eating volumers and selection
Marion Peel April 10, 2021
I have found this email very interesting as I had Colon cancer in 2017. I never eat beef, lamb or pork/ham but wonder if venison, pheasant, duck etc count as red meats as they are never mentioned.
Shirley Harrison April 10, 2021
Very informative and easy to understand especially the practical advice on cutting down. I think the message should be put out in the public domain as for the cancer implications of smoking
Angela Deighton April 8, 2021
Extremely useful and informative. I’ve learnt a lot. Keep up the good work!
group dating October 20, 2019
obviously like your website however you have to take a look at the
spelling on quite a few of your posts. Many of them are rife with spelling issues and I find
it very troublesome to tell the truth nevertheless I’ll certainly come back again.
Mrs Violet Marsh October 9, 2019
I had bowel cancer in 1982. I don’t eat red meat I eat chicken and plenty of veg and salad. Plus cheese and berries and natural yogurt.
The last 3 weeks I have been on Dr.Unwin diet. High fat lot carbs. I have lost 3lbs in weight, I am 90 years old.
Dr Peter Lewis October 1, 2019
please read the new research (published yesterday in Annals of medicine) on the very low likelihood of red meat causing any cancers! You have been misleading the public and should apologise now…
Louise June 18, 2019
This may be a silly question but I have been wondering if the same applies to vegetarian ‘meats’. For example, quorn make a range of sandwich filler fake meat such as chicken-style slices, bacon-style slices etc. Do these count as processed and contribute to cancer risk? I’ve tried to switch to more veggie alternatives but I’m wondering if they actually reduce your risks?
Katie Patrick June 20, 2019
Thanks for your question about meat alternatives. Vegetarian meat substitutes don’t count as processed meat and there’s no good evidence linking them to cancer. These products can be helpful for people trying to cut down on meat, but they aren’t always healthy and can be high in salt. So it’s a good idea to look for ones with mostly or all green on the label and think about using other vegetarian sources of protein including pulses, like lentils and beans, and eggs.
Katie, Cancer Research UK
Richard Feinman June 8, 2019
increased absolute risk of 0.08 %. Does anybody believe that the determination of individual diets was in the same ballpark of accuracy. And of course we are sure that the covered all the hundreds of confounders. Most important result is the need for science education for doctors and nutritionists. Or do I mean psychotherapy?
Ana May 31, 2019
Does eating organic meat make a difference?
Katie Patrick June 13, 2019
Thanks for your question about if organic meat makes a difference. More expensive or organic processed and red meat is not necessarily any healthier, so it’s better to cut down altogether rather than to switch to these. Instead, try swapping to fresh fish, fresh chicken or pulses like lentils and beans.
Katie, Cancer Research UK
Suen Oswell May 23, 2019
that didn’t answer my question
Susan Oswell May 23, 2019
What about smoked fish?
Katie Patrick June 13, 2019
Thanks for your question about smoked fish. The strongest evidence for foods that increase the risk of bowel cancer is for processed red meats, like bacon or salami. But any meat or fish that has been altered in some way to either extend shelf life or add flavour – including curing, smoking, salting and the addition of chemicals – counts as processed.
Katie, Cancer Research UK
Sallyann May 17, 2019
I believe sugar is more damaging than red meat. If only they would feed the animals what is natural for them to eat instead money is more important than our health. Red meat has been eaten for a very long time, admittedly we eat a lot more than we used to. but it is the way animals are feed now.
ProfMills May 16, 2019
Katie, thanks for your reply.
“Meats that have been transformed to either extend shelf life or add flavour count as processed. This includes things like curing, smoking, salting and the addition of chemicals such as nitrates or nitrites. Red meat includes things like fresh, minced and frozen beef, lamb and pork.”
According to this definition, fresh meat sausages are red meat not processed. Could the article’s title be corrected as it implies otherwise?
An EPIC study (DOI: 10.1186/1741-7015-11-63) found that “Significant associations with processed meat intake were observed for cardiovascular diseases, cancer ..” BUT “red meat intake was [not] associated with mortality”.
As red meat isn’t linked to cancer, could remove references to red meat be removed from this article?
Doug Bristor May 14, 2019
CRUK are so meat apologist. “Cutting down can make a difference, BUT it’s important to think about doing this as part of a healthy diet overall…..” Processed meat has strong correlation to obesity. Carcinogens don’t just stop in the bowel, they get absorbed around the body causing dna damage. Grrrr.
Carole Smith May 14, 2019
Regularly support cancer research uk and receive their magazine etc. I was aware of the links between red and processed meats and cancer but did not realise just how strong those links were. I’ll be cutting down!
Sue May 12, 2019
I notice that your research found that 40 people out of every 10,000 who eat 21g a day of red and processed meat get bowel cancer. Could you tell me how many people in 10,000, who eat no meat at all, get bowel cancer? Thank you.
Katie Patrick May 20, 2019
Hello Sue, thanks for your question about people who don’t eat any meat at all. In this study, people who didn’t eat any meat would have been included in the lowest category of meat consumption (those who ate less than 21g of red and processed meat a day), but this study didn’t directly compare vegetarians and vegans to meat eaters.
Katie, Cancer Research UK