Becoming a pescetarian can protect against bowel cancer, new research suggests.

People who ate a diet including fish and vegetables - but no meat - were 43 per cent less likely to develop the disease, a study found.

Vegetarians also had a 20 per cent reduced risk of developing cancer than meat-eaters.

The main risk factors for bowel cancer are consuming a lot of alcohol and red or processed meat, plus smoking and being overweight - particularly around the middle.

Vegetarians are also more likely to have a healthier diet in general therefore a reduced risk of obesity, the researchers said.

Becoming a pescetarian can protect against bowel cancer. A study found people who ate fish - but no meat - were 43 per cent less likely to develop the disease

Globally, Korea had the highest rate of colorectal cancer, followed by Slovakia and Hungary, according to the World Cancer Research Fund.

In the new study, US researchers found eating a pescetarian or a vegetarian diet was linked to lower risk of bowel cancers.

Vegetarians are less likely to be obese and evidence convincingly links increased fat around the middle to increased colorectal cancer risk.

The study involved 77,659 Seventh-Day Adventist men and women in the US - a substantial proportion vegetarians.

It identified 380 cases of colon cancer and 110 cases of rectal cancer.

Compared with non-vegetarians, pescetarians had a 43 per cent lower risk, and vegetarians had a 22 per cent lower risk.

Vegetarians had a 19 per cent lower risk for colon cancer and 29 per lower risk for rectal cancer.

HOW IS DIET LINKED TO BOWEL CANCER BOWEL CANCER? Colorectal cancer is the third most common cancer in the world, with nearly 1.4 million new cases diagnosed in 2012. Approximately 95 per cent of colorectal cancers are adenocarcinomas. Other types of cancer that can occur here include mucinous carinomas and adenosquamous carcinomas. The Continuous Update Project Panel (CUP) judged that there was convincing evidence that for men consuming red meat, processed meat and alcoholic drinks increases the risk of this type of cancer. Having a lot of body fat, abdominal fat, or being tall also increases the risk. For women, consuming alcoholic drinks increased the risk. The CUP is an ongoing project by the World Cancer Research Fund International analyses global research on how diet, nutrition, physical activity and weight affect cancer risk and survival. There was also convincing evidence that physical activity and consuming foods high in dietary fibre protect against this cancer. Garlic, milk and calcium probably protect and consuming alcoholic drinks (women) probably increase the risk of this cancer. Preventability estimates using the new findings from the Continuous Update Project show that about 47 per cent of cases of colorectal cancer in the UK can be prevented by eating and drinking healthily, being physically active and maintaining a healthy weight. Advertisement

Vegans had a 16 per cent lower risk of colorectal cancer while lacto ovo vegetarians – who eat milk and eggs – had an 18 per cent reduced risk.

Even becoming a part-time or semi-vegetarian reduced the risk by 8 per cent.

Assistant Professor Michael Orlich, of Loma Linda University, California, said: 'The results of this study seem consistent with prior evidence that often links the consumption of red meat, especially processed meats, to an increased risk of colorectal cancers.

'Although reduction in meat intake may be a primary reason for the reduced risk demonstrated in vegetarians, an increase in the consumption of various whole plant foods might also contribute to the reduction.

'In addition to reduced consumption of animal products, vegetarians ate less refined grains, added fats, sweets, snacks foods, and calorific beverages than did non-vegetarians and increased amounts of a wide variety of plant foods.

'Such a pattern might be expected to reduce hyperinsulinemia [where insulin levels in the blood are higher than normal] which has been proposed as a possible mechanism by which diet may increase colorectal cancer risk.

'In a similar manner, some research has suggested that insulin like growth factors and binding proteins may relate to cancer risk.'

Bowel cancer, also called colorectal cancer, is the third most common cancer in the world, with nearly 1.4 million new cases diagnosed in 2012.

Approximately 95 per cent of colorectal cancers are adenocarcinomas, a type of cancer that forms in mucus-secreting glands throughout the body.

Previous research from the World Cancer Research Fund International's Continuous Update Project (CUP), has found there was convincing evidence that for men, consuming red meat, processed meat and alcoholic drinks, having a lot of body fat or abdominal fat and height increase the risk of colorectal cancer.

The CUP is an ongoing programme which analyses global research on how diet, nutrition, physical activity and weight affect cancer risk and survival.

It found that in women, consuming alcoholic drinks increase the risk of cancer.

There was also convincing evidence that physical activity and consuming foods high in dietary fibre protect, as well as consuming garlic, milk and calcium, protects against the disease.

The study noted other research 'recently linked high levels of protein consumption, particularly animal protein, during middle age to an increased risk of cancer and higher mortality.

'The association between particular foods and colorectal cancers will be examined later in separate analyses.'

Researchers said pescetarians and vegetarians were more likely to eat increased amounts of a wide variety of plant foods

'Obesity could lie along a causal pathway from dietary pattern to colon cancer.'

He concluded: 'If such associations are causal, they may be important for primary prevention of colorectal cancers.

'The evidence that vegetarian diets similar to those of our study participants may be associated with a reduced risk of colorectal cancer.

'Along with prior evidence of the potential reduced risk of obesity, high blood pressure, diabetes and mortality, it should be considered carefully in making dietary choices and in giving dietary guidance.'

The new research comes just days after a British study found a diet high in fruit and vegetables helps lower the risk of heart disease and stroke.