Full listing: The cancers vegetarian and vegan diets might assist forestall – and people they enhance danger of, based on main new research

A vegetarian diet may help protect against five types of cancer, but it almost doubles the risk of oesophageal cancer, a landmark study has revealed. 

Experts welcomed the findings, which came from the largest study to date into the role of diet and cancer risk, saying the study underlines that cutting out meat may bring benefits – but it’s not risk-free.

The study, using data from more than 1.8million people, found vegetarians were up to 31 per cent less likely to develop pancreatic, prostate, breast, and kidney cancers as well as multiple myeloma – compared with meat-eaters.

Combined, these cancers account for around a fifth of cancer deaths in the UK. 

But they had a 93 per cent higher risk of developing the most common type of oesophageal cancer, whilst vegans were significantly more likely to be diagnosed with bowel cancer. 

The authors said more work is needed to establish whether meat itself is problematic – with meat-eaters in the study eating very little meat compared to the general population – or whether something specific in vegetarian diets lowers cancer risk. 

Either way, they said the answer might vary depending on cancer type – with ultra-processed foods thought to be driving the sharp rise in bowel cancer cases in young people. 

Here the Daily Mail presents a full list of cancers included in the study, and how cutting out meat may mitigate or increase the risk of the disease. 

Vegetarians are at a lower risk of kidney, blood, prostate, breast and pancreatic cancers

Professor Tim Key, study co-author from the University of Oxford, said: ‘Dietary patterns that prioritise fruit, vegetables and fibre-containing foods, and avoid processed meat, are recommended to reduce cancer risk.

‘Our study helps to shed light on both the benefits and risks associated with vegetarian diets.’

But, experts such as Prof Jules Griffin, a metabolic disease expert from the University of Aberdeen, have criticised the study, saying it fails to compare vegetarian diets to what could be ‘the optimum diet for reducing risk in the population for diet-associated cancer,’ where fish and meat are eaten in moderation. 

Gastrointestinal cancers: Vegetarian diets linked to doubled risk of oesophageal cancer – and doesn’t protect against bowel cancer either 

Whilst being vegetarian appeared to be protective overall, the scientists found that cutting out meat and fish resulted in nearly double the risk of oesophageal cancer. 

Oesophageal cancer is cancer that’s found anywhere in the food pipe, which carries food from the mouth to the stomach. Common symptoms include difficulty swallowing, indigestion or heartburn and unexplained weight loss. 

Around 9,000 people are diagnosed with the cancer every year in the UK, though rates are far higher in parts of Asia – where dietary intake of riboflavin, also known as vitamin B2, is thought to be much lower. 

Other risk factors include smoking, drinking alcohol and long-term acid reflux.

It is not clear why meat-eaters are less likely to develop the most common type of the disease, but experts suggested it may be linked to essential nutrients found in red meat, including iron, zinc and B vitamins. 

Interestingly, researchers found that participants who limited their intake of red meat but still ate poultry were around 36 per cent more likely to develop squamous cell carcinoma of the oesophagus compared to red-meat-eaters.

This suggests there is something specific in red meat – like haem iron, which is five times more likely to be absorbed into the body than non-haem iron – that has a protective effect. 

At the other end of the digestive tract is the intestines rectum – and another hotspot for cancers linked to vegetarian diets. 

Every year, around 44,000 people are diagnosed with bowel cancer in the UK, making it the fourth most common cancer. The disease, also known as colorectal cancer, kills around 17,000 people over the same time period. 

Symptoms include changes in bowel habits such as persistent diarrhoea or constipation, a feeling of incomplete emptying, and blood in the stool. 

Obesity, lack of exercise, and a diet high in ultra-processed foods and low in fibre have all been shown to raise the risk, with Cancer Research UK estimating that more than half of cases are preventable. 

And while bowel cancer rates have fallen among older adults, cases are rising at a worrying rate among younger, otherwise healthy people. 

Processed meat has come under particular scrutiny with experts suggesting that eating just two rashers of bacon – or 50g a day – can raise bowel cancer risk by nearly 20 per cent. 

Cancer Research UK estimates that around 5,400 bowel cancer cases a year are caused by eating processed meat. 

Yet the study found that vegans were 40 per cent more likely to develop bowel cancer than meat-eaters, spotlighting previous research suggesting that calcium may play a key role.

Cancer Research UK found that a glass of milk a day – one of the richest sources of calcium – may slash the risk of bowel cancer by almost a fifth. 

Commenting on the findings Dr Shireen Kassam, a consultant haematologist at King’s College Hospital, London, said: ‘Adequate calcium intake is known to protect against colorectal cancer, and modern well-planned vegan diets can readily meet this need.

‘This is not a simple story of veganism increasing cancer risk – it’s a reminder that all diets must be nutritionally well designed.’  

Pancreatic cancer: Cutting out meat could protect against the silent killer 

Vegetarians were 21 per cent less likely to develop pancreatic cancer, one of the deadliest forms of the disease, with more than half of patients dying within three months of diagnosis. 

It is typically diagnosed at a late stage, when treatment is difficult, because it causes few symptoms early on. 

Experts still don’t know what causes the majority of cases but have suggested at least one in ten are caused by being overweight or obese. 

This was reflected in the current study, with vegetarians having a lower body mass index (BMI) than meat eaters on average. 

The pancreas is a pear-shaped gland tucked behind the stomach. The gland produces hormones to aid digestion and convert sugar into energy. 

But in people with excess body fat, especially around the abdomen, the body’s tissue can become resistant to insulin, triggering the pancreas to make more, ultimately driving cancer development – though more research is needed to understand why. 

There is also some evidence that eating a lot of red and processed meat may raise the risk of pancreatic cancer, due to the formation of nitrosamines upon cooking – compounds known to cause cancer. 

Around 10,500 people are diagnosed with pancreatic cancer in the UK each year, with the majority of patients not diagnosed until the cancer has spread. 

Lower breast and prostate cancer risk  

A vegetarian diet was also shown to protect against cancers of the reproductive system.

Women who ate a vegetarian diet were around 9 per cent less likely to develop breast cancer, and men were 12 per cent less likely to develop prostate cancer than meat-eaters. 

Around 60,000 men are diagnosed with the disease each year in the UK, making it the most commonly diagnosed cancer in men. 

On average, one in eight men will be diagnosed in their lifetime, with risk increasing with age. But experts have warned that a growing number of cases are being detected in younger people.

Additives used to cure bacon have been shown to increase prostate cancer risk by a third, according to research published in the British Medical Journal. 

The French study found that sodium nitrate was linked with a 32 per cent increased risk of prostate cancer, while potassium nitrate was associated with a 22 per cent increased risk of breast cancer.  

Breast cancer affects one in seven women in the UK, with more than 56,000 new cases every year. It is the second biggest cause of cancer death in women, behind lung cancer.

Cancer Research UK maintains that death rates could be cut if more women adopted healthier lifestyles, including maintaining a healthy body weight. 

Poultry eaters were also found to have a lower risk of prostate cancer, whilst pescatarians were less likely to develop breast cancer.

Vegetarians at lower risk of blood and kidney cancers 

Vegetarians also had a 28 per cent lower risk of kidney cancer and 31 per cent lower risk of multiple myeloma, a type of blood cancer. 

The scientists said this may be because high animal-protein intake raises levels of protein in the blood, called kidney injury molecule-1, which has been linked to kidney damage. 

Circulating concentrations of the biomarker tend to be significantly lower in vegetarians and pescatarians than in meat eaters – potentially protecting them against kidney damage, which can then lead to cancer. 

One of the fastest-rising cancers in Britain, it is often dubbed a ‘silent killer’ because it rarely causes symptoms until it is advanced.   

Experts have long warned that by the time tell-tale signs such as blood in the urine appear, the cancer is often too advanced for successful treatment. 

Blood cancer risk was also lower, which researchers linked to a healthier body weight. With obesity being a major risk factor. 

Prof Key concluded: ‘Overall, the picture for vegetarians is quite optimistic.

‘But, like everyone else, vegetarians should ensure they replace missing nutrients through supplements or fortified foods.’