Cancer, the foods you love and the truth about your Sunday roast beef

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A series of studies have raised the alarm over red meat, particularly processed meat, linking it to bowel and colon cancers


The first bite of a bacon butty in the morning. A lunch of perfectly moist roast beef, paired with towering piles of crispy roast potatoes and doused in home-made gravy. For many, these are key ingredients to a perfect Sunday.

But in recent years, mounting evidence has suggested these simple pleasures, enjoyed too often, could wreak havoc on our health.

A series of studies have raised the alarm over red meat, particularly processed meat, linking it to bowel and colon cancers.

In 2015, the International Agency for Research on Cancer classified processed red meat – including sausages, bacon, ham and pâté – as a ‘definite’ cause of cancer, alongside cigarettes.

The World Cancer Research Fund advises eating ‘little, if any’ processed meat such as bacon and sausages, and only ‘moderate’ amounts of beef, pork and lamb.

A series of studies have raised the alarm over red meat, particularly processed meat, linking it to bowel and colon cancers

The NHS, too, recommends no more than 70g of cooked or processed meat every day – equivalent to one-and-a-half pork sausages, two rashers of bacon or one third of an average-sized sirloin steak. But will busting that limit put us on a fast-track to cancer?

The answer is probably not.

The current advice stems from a 2010 report by the Government’s Scientific Advisory Committee on Nutrition.

Scientists analysed evidence provided by hundreds of studies that had looked at the relationship between meat and cancer since the 1970s, involving millions of participants around the world.

Their conclusion, based on the analysed research, was that we should err on the side of caution and stick to 70g daily.

But many of the research included was flawed, leading even the committee itself to state: ‘Although a number of plausible biological mechanisms have been proposed to explain the association between red meat and colorectal cancer risk, none is supported by convincing evidence.’

Some studies did not distinguish between the effects of eating red meat – a steak, mince or a leg of lamb – and processed meat.

Others drew on dietary habits from outside of the UK where meat production – and ingredients in products – can be vastly different.

World Health Organisation data shows the colorectal cancer risk is 1.18 times higher if you eat 50 grams of processed red meat every day – roughly two slices of bacon. But the risk of any cancer is 40 times higher if you smoke, and 70 times higher for those who smoke and drink. (File photo)

And then there is the problem in the way the evidence is gathered.

Diet studies rely on participants remembering and then reporting what they’ve eaten over the course of a month or year – which is, for obvious reasons, unreliable.

And, most diets contain a huge variety of foods. So even after making complicated statistical adjustments, it is difficult to determine how any one thing has an effect.

Other studies have shown that, for instance, men who eat a lot of meat are also less likely to eat vegetables and fruit, and more likely to engage in other, unhealthy behaviours such as smoking and drinking alcohol.

RED MEAT CAN POSE A RISK – BUT IT’S SMALL

So are all the concerns simply misguided, nannying rubbish? Well, not entirely. There is some legitimate concern over the link between processed red meat – bacon, ham and such like – and the risk of bowel cancer. 

The issue is thought to lie with chemicals called nitrates that are added to meat products in order to lengthen their shelf life. Once inside the stomach, these react with bacteria to form nitrosamines, which are known to be involved in the development of bowel cancers.

A Cancer Research UK study of half a million adults, published in the European Journal Of Epidemiology in April, found that those who ate the most processed meat were 20 per cent more likely to get bowel cancer than those who ate the least.

Mediterranean diets high in fresh fish, nuts, fruit, vegetables and olive oil can cut the risk of breast cancer.

Coffee contains cancer-causing acrylamide – but only 1-2 micrograms per cup. Below 208 micrograms daily is safe.

But it is worth putting this into context. Last year, Tom Sanders, professor of nutrition and dietetics at King’s College London, told us: ‘Only one in a hundred cases of colorectal cancer is said to be related to processed red meat compared to 64,500 cancers a year caused by smoking.’

World Health Organisation data shows the colorectal cancer risk is 1.18 times higher if you eat 50 grams of processed red meat every day – roughly two slices of bacon. But the risk of any cancer is 40 times higher if you smoke, and 70 times higher for those who smoke and drink. 

It all means that on a population level, if every person eats lots of processed meat, it would result in a significant number of extra cancer cases. But for an individual, the risk is small.

And this is precisely the point of the highly controversial study on meat published last week.

Although the research, published in Annals Of Internal Medicine, concluded that eating just under two bacon rashers every day for most of your life is likely to increase the risk of colorectal cancer, the evidence isn’t strong enough to warrant cutting back significantly. The benefits of cutting back – the scientists suggest – are ‘trivial’.

Diet studies rely on participants remembering and then reporting what they've eaten over the course of a month or year – which is, for obvious reasons, unreliable. And, most diets contain a huge variety of foods. So even after making complicated statistical adjustments, it is difficult to determine how any one thing has an effect

Diet studies rely on participants remembering and then reporting what they’ve eaten over the course of a month or year – which is, for obvious reasons, unreliable. And, most diets contain a huge variety of foods. So even after making complicated statistical adjustments, it is difficult to determine how any one thing has an effect

The report recommends that eating up to four portions of red or processed meat every week poses no risk – contrary to almost every other guideline from official health bodies around the world.

Pharmacologist David Colquhoun, a professor at University College London, adds: ‘We have no absolute proof that meat causes cancer.

‘To get that, we’d need to lock people away on a closed ward and feed them a high meat diet for their entire lives to see what happened to them.’

Prof Colquhoun says the risk posed by red meat specifically has decreased as the evidence has mounted over the years. ‘The EPIC study in 2013, which followed nearly half a million people over more than 12 years, found red meat posed no detectable risk of death. The increased risk was about two per cent.’

There are now important questions over whether the evidence from studies – however weak – might point to there solely being a risk from processed meat.

Writing in 2017 in the British Medical Bulletin, Dr Ian Johnson, emeritus fellow at Quadram Institute Bioscience, said: ‘The evidence for an association with colorectal is stronger for processed meat than for red meat, and indeed some still argue that the evidence in relation to red meat remains too weak and inconsistent to justify a conclusion.’ 

So, risk-averse types might simply choose to neglect the odd sausage or slice of bacon. But forgoing your Sunday roast or the odd bacon sandwich? That’s just silly.

Fruit and veg are good – but you don’t need to overdo it

Guidelines recommend eating five portions of fruit and veg every day. And most surveys suggest we are actually doing pretty well already, with the average Briton consuming four portions a day. But might that be too little?

Recent research suggested we may need to double our efforts to protect against cancer and early death.

A major study from experts at Imperial College London suggested that ten portions a day reduced the risk of cancer overall by 13 per cent.

If we all did it, millions of lives could be saved, it was claimed.

So what is it about munching through vast quantities of veg that has this magical effect?

Hilary Powers, emeritus professor of nutritional biochemistry at Sheffield University, says the main message is that 'eating some fruit and veg is better than none'

Hilary Powers, emeritus professor of nutritional biochemistry at Sheffield University, says the main message is that ‘eating some fruit and veg is better than none’

According to the World Cancer Research Fund, fruit and non-starchy vegetables contain compounds such as fibre, vitamins, minerals and other nutrients, that have the potential to fight tumours.

But it is hard to actually know if this is the reason lower cancer rates are seen in people who eat lots of them.

A recent Cambridge study of more than 50,000 British households found that people with more money spent more on ‘healthier’ foods – rather than those which are high in calories, fats, refined starches and sugars – and bought more fruit and vegetables. By contrast, those with less to spend bought less fresh fruit and veg and more high-fat, high-sugar, high-calorie foods.

And it’s been shown in many studies that those who are better off are more likely to do other things that are healthy, such as exercise, and not smoke or drink too much.

Interestingly, findings from an ongoing European study that is tracking nearly half a million people to investigate the relationships between diet, lifestyle and cancer found that those who followed a pescatarian diet – eating fish but not meat – had a lower colorectal cancer risk compared to people who were completely veggie and those who ate meat, but not much fish.

In veggies and omnivores, the risk of colorectal cancer did not differ. So it could be fish that’s protective.

Hilary Powers, emeritus professor of nutritional biochemistry at Sheffield University, says the main message to take away is that ‘eating some fruit and veg is better than none’.

She adds: ‘It’s important to understand that eating some fruit and vegetables each day, rather than none at all, can significantly reduce the risk of some cancers.’

DON’T STOP ENJOYING YOUR CRISPY ROASTIES

The gnarly, crisp ridges of a roast potato are, according to many, the best part of a Sunday roast.

For many, it’s a case of the browner, the better.

But a preference for overdone roasties could leave you privy to ‘toxic cancer agents’, some reports would have you believe. In 2017, following a series of studies, the Food Standards Agency warned of the possible risks involved with over-cooking foods, particularly those high in starch.

The concerns related, specifically, to roasted potatoes, burnt toast and frozen chips.

The watchdog encouraged us to ‘go for golden’ after research found high levels of the chemical acrylamide – a known carcinogen – in foods that are burned or over-cooked. The chemical is formed when compounds in these foods – water, sugar and amino acids – combine together when heated at high temperatures.

Scientists have shown that mice which had been fed large doses of acrylamide develop multiple tumours.

And this led to the World Health Organisation labelling acrylamide as a ‘probable carcinogen’.

The gnarly, crisp ridges of a roast potato are, according to many, the best part of a Sunday roast. For many, it's a case of the browner, the better. But a preference for overdone roasties could leave you privy to 'toxic cancer agents', some reports would have you believe. File image

The gnarly, crisp ridges of a roast potato are, according to many, the best part of a Sunday roast. For many, it’s a case of the browner, the better. But a preference for overdone roasties could leave you privy to ‘toxic cancer agents’, some reports would have you believe. File image

But according to the European Food Safety Authority, its ruling may be over-cautious.

First of all, there are many everyday substances that are considered a ‘probable carcinogen’, including hot drinks. The only confirmed link between acrylamide and tumours is in animals alone.

And the amount of acrylamide seen to be harmful was the equivalent of eating at least 40 slices of burned toast per day, for a number of weeks.

Toxicology studies have shown that humans and rodents absorb acrylamide at different rates, and process it differently.

One such study, from 2009, published in the journal Food And Chemical Toxicology, suggested that humans quickly process and excrete any acrylamide we eat, which protects against negative effects.

A 2015 Italian review of research, which examined links between acrylamide and 14 different types of cancer, found ‘no meaningful association’ with most cancer types, apart from a ‘modest association’ – and remember, this doesn’t equate to cause and effect – with kidney, endometrial and ovarian cancers.

‘The evidence linking acrylamide to cancer is weak and inconsistent,’ says Katie Parker, from Cancer Research UK.

‘The likelihood of eating so much burnt toast that it significantly impacts on your cancer risk is very, very small.’



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