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Dr Michael Mosley reveals the truth about processed meat and cancer

The news last week was enough to make anyone wonder what to believe about healthy eating. 

For more than a decade, Government agencies have warned us to cut down on the red and processed meat we eat. But last week, as one reporter put it: ‘Health chiefs have revealed bacon is safe to eat after all!’

We had previously been told that more than a few rashers of bacon a week could increase our risk of bowel cancer by as much as 20 per cent. The safe daily limit for red meat was 70g – equivalent to half a beefburger, one-and-a-half sausages, or just a third of an 8oz steak.

Like most people, I was confused as to how seriously to take these claims, but cut back anyway. 

One in 14 men and one in 19 women will be diagnosed with bowel cancer during their lifetime. And no one wants any additional risk. But then, last week, came what appeared to be a major scientific flip-flop. 

For more than a decade, Government agencies have warned us to cut down on the red and processed meat we eat. But last week, as one reporter put it: 'Health chiefs have revealed bacon is safe to eat after all!'

For more than a decade, Government agencies have warned us to cut down on the red and processed meat we eat. But last week, as one reporter put it: ‘Health chiefs have revealed bacon is safe to eat after all!’

A new review of the best available evidence – the very same evidence that underpinned worldwide guidance on meat consumption – suggested there was hardly any risk at all.

One of the contributors to the report, Dr Bradley Johnston, from Dalhousie University in Canada, said: ‘Any health benefits from staying away from meat are uncertain and, if they exist at all, are very small.

‘We suggest individuals continue their current consumption of red meat and processed meat.’

Anyone reading this would be forgiven for thinking: ‘They say one thing, then the opposite. I’m just going to ignore it all from now on.’

Experts, too, recognise that if there is too much conflicting advice the public will just switch off, which is not in anyone’s interests.

So how can you separate the myths from the genuine messages we should all be taking seriously to maximise the health benefits from our diet?

In an effort to clarify the issues, The Mail on Sunday has spoken to scientists who have devoted their careers to studying food and cancer.

Here, we’ll examine the most prevalent diet trends said to be linked to – or claim to protect against – cancer.

Is bacon safe or not? There have been health scares about roast potatoes and even toast – are they really true? How many portions of fruit and veg a day is enough to make a real difference to your risk of cancer? And should we cut out sugar?

What follows are hopefully reliable answers based on the best scientific evidence. But, of course, it is important to point out that interpreting any claims about the effect of diet is fraught with difficulties.

In other areas of medicine, for example testing a new drug, there are clear-cut ways of measuring a specific effect. You take a group of patients, randomly divide them in two and give both groups pills, but only one group gets the active drug. The other is given a placebo. Then you look for differences.

But this is impossible to do when it comes to establishing whether, say, people who eat broccoli get cancer less often. For a start, the potential effects of broccoli may not be seen for decades.

Obviously, you cannot be certain that the groups allocated to eating broccoli will stick to it, or accurately report what they have eaten.

That’s why most nutritional claims are based on what are known as observational studies, which rely on people reporting what they eat and allowing researchers to get updates on their health as they age.

The trouble is, broccoli-eaters often have other healthy habits so you can’t be sure whether it was the broccoli-eating that caused a particular effect. You also cannot tightly control their diets, so it becomes extremely difficult to work out whether broccoli caused an effect.

So despite huge advances in statistical analysis, many dietary claims – while made with the best of intentions to improve public health – are open to criticism and debate.

Much of it comes down to interpretation and how the findings are presented. Still, it is possible to cut through the hype and make an informed judgment, which is what we have tried to do here.

And what you do after that, ultimately, is up to you.

Is your Sunday roast beef really as bad as smoking? Don’t be ridiculous!

By JO MACFARLANE for the Mail On Sunday 

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

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

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.

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.’

Do trendy low-carb diets RAISE the risk of cancer?

First came the Atkins, Dukan and South Beach diets. Today, it’s the trendy ketogenic diet, or keto, a low-carb, high-fat plan which even has its own internet hashtag #LCHF.

Advocates claim that these approaches help people shed weight fast, control blood sugar, beat type 2 diabetes, and even fight off cancer by avoiding eating carbohydrates.

People swap pasta for strips of courgette, rice for finely shredded cauliflower, and bread for lettuce leaves.

Some of these diets are more restrictive than others. They range from 130g of carbs a day – which would mean you could still eat a large baked potato, a portion of rice and still have some left over – to just 30g, which is the equivalent of just two slices of wholemeal bread.

That it helps shift weight is in no doubt. Abandoning carbs involves stripping significant calories from your diet.

First came the Atkins, Dukan and South Beach diets. Today, it¿s the trendy ketogenic diet, or keto, a low-carb, high-fat plan. Advocates claim these approaches help people shed weight fast, control blood sugar, beat type 2 diabetes, and even fight off cancer by avoiding eating carbohydrates, including pasta (file photo)

First came the Atkins, Dukan and South Beach diets. Today, it’s the trendy ketogenic diet, or keto, a low-carb, high-fat plan. Advocates claim these approaches help people shed weight fast, control blood sugar, beat type 2 diabetes, and even fight off cancer by avoiding eating carbohydrates, including pasta (file photo)

But while it is touted as one of the most effective ways to slim, there may well be a huge downside to following the lowest-carb plans in the longer term. 

A review of the data, published in the European Heart Journal in April, found a ‘significant and positive’ chance that these diets were associated with an increased risk of dying from ‘any form’ of cancer.

The study, carried out by experts from an international panel, involved looking at half a million participants over a period stretching up to 16 years.

Initially, they examined 24,825 people who had taken part in the US National Health and Nutrition Examination Survey during 1999 to 2010. They found those eating the least carbs were, overall, 32 per cent more likely to die of any cause, and 35 per cent more likely to die of cancer than those eating the most carbs.

These findings were then confirmed by combining the results of a further seven studies involving nearly 450,000 people, which revealed very low-carb dieters were eight per cent more likely to die of cancer. Of course, these studies were based on surveys, so it’s hard to be sure if factors other than carb intake were also at play.

While it is touted as one of the most effective ways to slim, there may well be a huge downside to following the lowest-carb plans in the longer term. A review of the data, published in the European Heart Journal in April, found a ¿significant and positive¿ chance that these diets were associated with an increased risk of dying from ¿any form¿ of cancer. (Above, courgette strips, which followers of the diet eat instead of pasta)

While it is touted as one of the most effective ways to slim, there may well be a huge downside to following the lowest-carb plans in the longer term. A review of the data, published in the European Heart Journal in April, found a ‘significant and positive’ chance that these diets were associated with an increased risk of dying from ‘any form’ of cancer. (Above, courgette strips, which followers of the diet eat instead of pasta)

But lead author Professor Maciej Banach, from the Medical University of Lodz in Poland, said: ‘These diets should be avoided.

‘They might be useful in the short term to lose weight, lower blood pressure and improve blood glucose control, but our study suggests that in the long term they are linked with an increased risk of death from any cause.’

A crucial problem is that very low-carb diets often lack fibre – plant matter which comes from bread, oats, grains and many fruits and veg. 

Fibre has long been proven to have a protective effect against bowel cancer specifically, a condition which affects one in 15 men, and one in 18 women in the UK. More than 50 per cent of cases are preventable, and 28 per cent are linked to consuming too little fibre.

Serve meat with a yogurt dip – ‘good’ bacteria neutralises any carcinogenic chemicals formed when grilling.

Some say an alkaline diet – free of acidic foods like citrus fruits – protects against cancer. But no study has ever proved the claim.

The official advice is that, by eating three portions of fibre-rich foods a day – from porridge, fruit and veg to a slice of bread or a handful of nuts – our risk could reduce by 20 per cent.

It we all did this, it could save thousands of lives.

Fibre is protective in two ways. First of all, it increases the bulkiness of our waste and reduces the amount of time it takes to move through our digestive system, which means toxins spend less time in the bowel.

It also provides fuel for the ‘good’ bacteria in our systems, which in turn produces a fatty acid called butyrate. This protects the cells in the bowel and makes tumours less likely to develop.

As it stands, nine in ten adults fail to consume the recommended 30g of fibre a day as it is. So cutting out food groups that contain fibre may mean straying even further from the target.

A crucial problem is that very low-carb diets often lack fibre ¿ plant matter which comes from bread, oats, grains and many fruits and veg

A crucial problem is that very low-carb diets often lack fibre – plant matter which comes from bread, oats, grains and many fruits and veg

Dr Ian Johnson, emeritus fellow at the Quadram Institute Bioscience, says: ‘Based on the evidence, eating a diet low in fibre over a long period of time could lead to an increased risk of colorectal cancer.

‘A ketogenic diet over just a couple of years might not have an effect – but the truth is, we just don’t know.

‘The protective effect of fibre might be about two-fold if you compare those who eat least with those who eat the most.’

CUTTING OUT SUGAR WON’T CURE CANCER

The email spread like wildfire. It looked like a paper from the respected US research institution, Johns Hopkins University in Baltimore, and contained the claim: ‘Sugar is a cancer-feeder. By cutting off sugar, it cuts off one important food supply to the cancer cells.’

There was only one problem – it was a hoax.

But it became so widespread when it was circulated in 2007 that staff at Johns Hopkins were forced to issue a public statement to deny any involvement.

The theory persists, however, and is regularly trumpeted on social media by health gurus to justify cutting all sugar – but particularly refined white sugar – out of the diet completely.

Sugar is often described by its opponents as ‘cancer’s favourite food’ and the ‘white death’.

One well-worn health myth is that the man-made sweetener aspartame ¿ used in everything from fizzy drinks, including Diet Coke and Coke Zero, to chewing gum ¿ causes cancer (as well as multiple sclerosis, blindness, depression, memory loss and birth defects). The theory has been thoroughly debunked

One well-worn health myth is that the man-made sweetener aspartame – used in everything from fizzy drinks, including Diet Coke and Coke Zero, to chewing gum – causes cancer (as well as multiple sclerosis, blindness, depression, memory loss and birth defects). The theory has been thoroughly debunked

The myth suggests that cancer cells need lots of glucose – the fuel which powers all of the body’s cells – to develop, so cutting it out will literally starve the cancer and stop it from growing.

While it sounds convincing, it is simply not true.

Katie Patrick, a nutrition expert from Cancer Research UK, warns: ‘All our healthy cells need glucose too, and there’s no way of telling our bodies to let healthy cells have the glucose they need, but not give it to cancer cells.’

Following severely restricted diets with very low amounts of carbohydrate could damage health in the long term by eliminating foods that are good sources of fibre and vitamins, they add.

This is particularly important for cancer patients, because some treatments can result in weight loss and put the body under a lot of stress.

While on the subject of sweet things, another well-worn health myth: the man-made sweetener aspartame – used in everything from fizzy drinks, including Diet Coke and Coke Zero, to chewing gum – causes cancer (as well as multiple sclerosis, blindness, depression, memory loss and birth defects). The theory has been thoroughly debunked. Yet rumours, often in the form of fake health news posted online, continue to circulate.

Since aspartame was launched in the 1980s, studies have suggested that it could be linked to increased rates of brain tumours and leukaemia in rats, leading to worrying headlines.

But it was later revealed that some animals were fed the equivalent in sweetener to 20 cans of Diet Coke, every day, for months, until they died. Despite this fact, the whiff of suspicion remains: in 2015, Pepsi dropped aspartame from its US Diet Pepsi drink in response to consumer fears over safety, replacing it with sucralose, another type of sweetener.

Yet the overwhelming evidence from robust scientific trials is that aspartame is safe.

No human studies have found any link to cancer or other problems, and two major reviews – by the European Food Safety Authority and US National Cancer Institute – have concluded the sweeteners are safe.

Sophia Lowes, health information manager at Cancer Research UK, says: ‘The link to cancer was between sweeteners and animals but it was never translated into a link in humans.’

There’s no such thing as a cancer-busting superfood

Blueberries contain powerful compounds that can protect against cancer. Green juice and celery smoothies can even fight – and reverse – the disease.

These tales are undeniably appealing because they seem so simple. But the truth is that superfoods for cancer do not exist.

At best, their virtues are at least rooted in scientific theory – but they are exaggerated.

Take those blueberries, for example. Scientists in the United States discovered that they contained anthocyanins, a compound thought to have anti-cancer properties which helps clear out toxins, fights damaging compounds in the body and reduces inflammation.

Blueberries contain powerful compounds that can protect against cancer. Green juice and celery smoothies can even fight ¿ and reverse ¿ the disease. These tales are undeniably appealing because they seem so simple. But the truth is that superfoods for cancer do not exist

Blueberries contain powerful compounds that can protect against cancer. Green juice and celery smoothies can even fight – and reverse – the disease. These tales are undeniably appealing because they seem so simple. But the truth is that superfoods for cancer do not exist

A Californian study in 2013 found that feeding mice with a diet which was five per cent powdered blueberry reduced the size of their cancer tumours.

And last year, another US team reported that human cancer cells reduced by 25 per cent in the laboratory when exposed to blueberry extract.

Chemical compounds extracted from, or similar to, those found in blueberries and various other vegetables are being made into cancer drugs, and studied.

It all certainly sounds impressive. But none of this proves that consuming even large amounts of blueberries every single day of your life will prevent cancer.

Indeed, animal studies often use implausibly high amounts of a compound, which can’t be replicated through diet and may even be harmful. 

Gunter Kuhnle, professor of food and nutritional sciences at Reading University, says: ‘If you put anything on cancer cells they tend to die. I’ve been to a conference where someone poured a can of coke on to cancer cells and, surprise surprise, they died.’

There have been studies that reported that people who included a lot of berries in their diet had marginally lower cancer rates.

However, Prof Kuhnle is highly sceptical, saying: ‘In many populations where they’re studied, berries are expensive. So you’re looking at people who can afford them.

‘These people are wealthier and healthier in general – and we know that has a big influence on cancer.’

According to Prof Louis Levy, of Public Health England: ‘If you take in a lot of these so-called superfoods, all you’re doing is enriching the drainage system of the UK with antioxidants, because your system will just flush them out.’

It’s too much of everything that really causes cancer

Consuming too many calories – whether they come from sugar, bacon, potatoes, toast or blueberries – will eventually lead to you gaining weight. And being overweight or obese increases your risk of 13 different types of cancer, including bowel, stomach, pancreatic, liver and post-menopausal breast cancer.

In fact, it’s the single biggest trigger for the disease in the UK after smoking.

Naveed Sattar, professor of metabolic medicine at Glasgow University, says: ‘Sugar doesn’t cause obesity or cancer. But consuming excess calories will make you put on weight, and the extra weight will increase your risk of cancer.’

Mangesh Thorat, of the Centre for Cancer Prevention at Queen Mary University of London, adds: ‘We know the most important thing for most cancers is keeping your weight down. Other than that, relating to diet, there’s nothing specific or evidence-based as an intervention.’

Consuming too many calories ¿ whether they come from sugar, bacon, potatoes, toast or blueberries ¿ will eventually lead to you gaining weight. And being overweight or obese increases your risk of 13 different types of cancer

Consuming too many calories – whether they come from sugar, bacon, potatoes, toast or blueberries – will eventually lead to you gaining weight. And being overweight or obese increases your risk of 13 different types of cancer

Your risk increases the longer you remain overweight – but small changes, maintained over time, can make a huge difference.

An early sign that weight loss may have a protective effect comes from the work of Roy Taylor, professor of medicine and metabolism at Newcastle University. He pioneered a very low-calorie diet that can, in some patients, reverse type 2 diabetes.

Participants consumed 800 calories a day for 12 to 20 weeks by drinking low-cal shakes.

They then reverted to the Government’s EatWell plate, which allows a third of the diet to be carbs – and consumed plenty of wholegrains, fruit and vegetables, lean meats and pulses.

Their progress was monitored and compared with a group who didn’t follow the programme or any other weight-loss plan.

After a few months, the majority of those on the diet had normal blood sugar levels, and no longer needed medication for diabetes.

Two years later, many had maintained their health.

But there was a surprising additional finding. In the group who didn’t follow the plan, there were five weight-related cancer cases – and none among those who did diet.

Prof Taylor said losing weight may affect the speed at which cancer grows.

Prof Sattar adds: ‘Why weight loss may protect against cancer is unknown, but in women, obesity can affect the sex hormones which can then accelerate the growth of certain types of cancer, particularly endometrial – cancers of the womb lining. Those who put on weight will accumulate fat in the liver, which drives inflammation, leads to scarring and, eventually, to liver cancer.

‘There are other drivers, but we just don’t know yet what they are. The only certainty is that there is a link with obesity.’

And don’t forget to consider alcohol as part of the weight-loss equation. An evening glass of wine or a pint of beer contributes to your daily calorie total – and alcohol itself is a risk factor for cancer, even independent of weight.

The World Cancer Research Fund reports that breast, bowel, liver, stomach, mouth and oesophageal cancers are all strongly related to alcohol.

In most cases, the risk begins to rise if you’re consuming two to three units every day – that’s just one medium glass of wine.

DR MICHAEL MOSLEY: Could fasting 16 hours a day REALLY help you keep cancer at bay?

By DR MICHAEL MOSLEY for the Mail On Sunday

In the articles above, we’ve revealed the truth about food and cancer. Contrary to popular belief, there is no one thing – whether that’s red meat, bacon, toast, roast potatoes or anything else we eat – that raises the risk significantly.

It’s overall diet that really matters. If we eat too much, we end up becoming overweight. But the fact that carrying too much fat, particularly around the middle, is linked to cancer is something that still surprises a lot of people.

If you’ve got fat around your tummy, you probably also have quite a lot of visceral fat – that’s the name for fat that builds up inside the abdomen and around the organs.

The cancers which are particularly strongly linked to excess fat are breast and bowel, two of our most common forms of the disease. So keeping to a healthy weight and keeping your tummy trim ¿ ideally your waist should be less than half your height ¿ are great ways to reduce your cancer risk. And I believe one of the best ways to do this is through intermittent fasting

The cancers which are particularly strongly linked to excess fat are breast and bowel, two of our most common forms of the disease. So keeping to a healthy weight and keeping your tummy trim – ideally your waist should be less than half your height – are great ways to reduce your cancer risk. And I believe one of the best ways to do this is through intermittent fasting

And it is a problem, because it doesn’t just sit there, wobbling. Visceral fat is active, sending out signals to the rest of your body.

Some of these signals make your cells divide more rapidly, which increases your risk of cancer, while others cause inflammation, another big driver of cancer.

According to Cancer Research UK, being overweight or obese leads to about 22,800 new cases of cancer each year.

The cancers which are particularly strongly linked to excess fat are breast and bowel, two of our most common forms of the disease.

Cancers of the pancreas, oesophagus and gallbladder, all of which are extremely hard to treat, are also linked to obesity.

According to Cancer Research UK, being overweight or obese leads to about 22,800 new cases of cancer each year. (File photo)

According to Cancer Research UK, being overweight or obese leads to about 22,800 new cases of cancer each year. (File photo)

So keeping to a healthy weight and keeping your tummy trim – ideally your waist should be less than half your height – are great ways to reduce your cancer risk.

And I believe one of the best ways to do this is through intermittent fasting.

It can not only cut your risk of developing cancer but may even boost the effectiveness of treatments such as chemotherapy, if you are unlucky enough to need it.

HOW 5:2 COULD HELP FIGHT BREAST CANCER

Seven years ago I wrote a book, The Fast Diet, with journalist Mimi Spencer, in which we outlined the potential benefits of going on a 5:2 intermittent fasting diet. This is one where you reduce your calories to about 600 twice a week.

I suggested it would not only help you lose weight, but, according to studies carried out on animals, might also help cut your risk of developing cancer.

Since then, studies in humans have indicated the same.

Seven years ago I wrote a book, The Fast Diet, with journalist Mimi Spencer, in which we outlined the potential benefits of going on a 5:2 intermittent fasting diet. This is one where you reduce your calories to about 600 twice a week

Seven years ago I wrote a book, The Fast Diet, with journalist Mimi Spencer, in which we outlined the potential benefits of going on a 5:2 intermittent fasting diet. This is one where you reduce your calories to about 600 twice a week

British scientists Dr Michelle Harvie and Professor Tony Howell have carried out studies that showed intermittent fasting helped improve insulin resistance in one group of women. 

Insulin resistance is a measure of how much of the hormone your body has to produce to bring your blood sugars down after a meal.

Another group of women who dieted every day also lost weight, but didn’t see the same insulin improvement. This is important because having high levels of insulin increases your cancer risk.

So a combination of weight loss and improvement in insulin sensitivity could be highly beneficial.

In another more recent study, Dr Harvie asked 23 overweight, pre-menopausal women at high risk of breast cancer to cut back their calories, two days a week, for one menstrual cycle. 

This time, as well as standard tests, they agreed to have breast biopsies. Over the course of a month, the women lost an average of three kilos (more than 6 lb), most of it body fat.

In most of the women there were significant changes in the activity of genes associated with breast cancer.

Bigger studies would be needed to really prove intermittent fasting, rather than weight loss generally, was responsible. But the results are interesting.

SKIPPING BREAKFAST COULD BE A GOOD IDEA

In The Fast Diet, I also wrote about a different form of intermittent fasting, one called time restricted eating. It’s also known as 16:8, and you don’t worry about calories when doing this plan. Instead, you limit the hours within which you eat your meals.

Many of us don’t finally finish eating and drinking until about 10pm thanks to a late-night snack, and then we start eating again soon after we wake up. That means we go without food for about nine hours.

DO YOU HAVE A QUESTION FOR DR MOSLEY? 

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The idea behind time restricted eating is to extend the length of your ‘overnight fast’ to 12, 14 or even 16 hours by finishing eating earlier in the evening and starting again much later – basically, skipping breakfast the following day.

It has been shown to help people lose weight. But can it also reduce your cancer risk?

In a large study, 2,400 American women with breast cancer were randomly allocated to either a low-fat diet or given general health advice.

They were then followed over the next seven years to see if going on a low-fat diet made any difference to the risk of breast cancer recurring. The answer was a resounding ‘no’.

Despite reducing their fat intake by 19 per cent, the low-fat dieters were no better off than those in the control group.

But the great thing about this study, from the point of view of researchers investigating time restricted eating, is that the women were asked to keep detailed records of when they ate.

The women whose diaries showed that they had fasted for more than 13 hours a night had 36 per cent less chance of a breast cancer recurrence than those who had been fasting for under 13 hours.

There is a lot more information about intermittent fasting, foods and their impact on cancer in my latest book, the Fast 800. You can also find additional information at thefast800.com.

Low-cal diet hope for chemo patients

Could a strict five-day diet help in the fight against cancer? That’s exactly what scientists across the world are trying to find out.

They are looking into the Fast Mimicking Diet – the brainchild of Professor Valter Longo, who heads the Longevity Institute at the University of Southern California in Los Angeles.

He created a diet where you live on about 800 calories a day for five days, then eat normally for the rest of the month.

This cycle can be repeated every one to six months, depending on your diet goals. Prof Longo believes that if you drastically reduce food – and therefore energy supply – cells go into ‘a highly protected non-growth mode’. In other words, they hunker down and wait for better times.

He believes this diet could also help patients going through chemotherapy, one of the main treatments for cancer. Chemotherapy drugs kill off cells that grow rapidly, which is what cancer cells do.

But other healthy cells – such as hair cells and those in the gut – also divide rapidly. This is why treatment can cause hair loss and nausea.

The theory is that if you could slow down the growth of normal cells by fasting prior to chemo, that might protect them during the treatment, while still leaving the tumour cells vulnerable to attack.

There are medical trials happening right now that are trying to find out if Prof Longo’s diet might do just that.

He is adamant, however, that people should not try to do this without consulting their doctor.

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