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It’s not new news that processed and red meat are linked to bowel cancer. But meat was back in the news last week after research we funded, and press released, took a closer look at how much meat might be enough to increase bowel cancer risk.

The new 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?

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.

This places bacon in the same group as tobacco. But IARC groups simply state how certain we can be, based on the evidence, that something causes cancer, not the amount of cancers it causes. This means the evidence that processed meat causes bowel cancer is as strong as it is for tobacco causing cancer, but smoking is responsible for far more cases of cancer than processed meat.

IARC also classified red meat as a ‘probable’ cause of cancer. You can read about this in depth in this blog post we published at the time.

Processed meat causes cancer

Copy this link and share our graphic. Credit: Cancer Research UK

How does processed and red meat cause cancer?

So far, research has linked three 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 three 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 and found that moderate processed and red meat eaters had a 20% increased risk of bowel cancer compared to low meat eaters. To put this in context, for every 10,000 people on the study who ate 21 grams of red and processed meat a day, 40 were diagnosed with bowel cancer. Eating 76 grams of processed or red meat a day caused 8 extra cases of bowel cancer per 10,000 people.

A 2018 review of the evidence found an increased risk of bowel cancer for every 50 grams of processed meat and 100 grams of red meat someone eats a day.

The latest study looked at even smaller amounts and found an increased risk starting at just 25 grams of processed meat a day, the equivalent of one rasher of bacon. This confirms that no matter how much processed meat you eat, eating less can reduce your bowel cancer risk.

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?

Eating foods high in fibre, especially wholegrains like wholemeal bread or brown rice, and doing lots of physical activity can reduce the 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.

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.

“The data from our study does suggest that eating little to no processed and red meat lowers the risk of bowel cancer, but the increased risk at lower intakes is small so this doesn’t imply that everyone needs to give up meat altogether,” says Key.

Cutting down 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 several types of cancer, and have more impact on risk 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

Comments

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Katie Patrick June 20, 2019

Hi Louise,

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.

Best wishes,

Katie, Cancer Research UK

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 13, 2019

Hi Ana,

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.

Best wishes,

Katie, Cancer Research UK

Katie Patrick June 13, 2019

Hi Susan,

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.

Best wishes,

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?

Suen Oswell May 23, 2019

that didn’t answer my question

Susan Oswell May 23, 2019

What about smoked fish?

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

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.