Eating fish may lower risk of bowel cancer: study

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A new study provides stronger evidence on the health benefits of eating more fish.

Eating more fish could reduce the risk of bowel (colorectal) cancer, according to new research published in Clinical Gastroenterology and Hepatology which looked at the dietary patterns of nearly half a million people.

The new study, which was funded by World Cancer Research Fund (WCRF), followed 476,160 people for 15 years from Denmark, France, Germany, Greece, Italy, the Netherlands, Norway, Spain, Sweden and the UK.

Previous research by WCRF only found limited evidence that consuming fish may be linked with a reduced risk of bowel cancer. This study found that those who ate more than three 100g portions of fish a week had a 12% lower risk of developing bowel cancer compared to those who ate less than one portion a week.

Eating more than 51.3g of fish a day (359.1g a week) was associated with a 12% decreased risk of bowel cancer compared to those we ate less than 9.07g of fish a day (63.49g a week).

Current UK diet guidelines suggest eating at least two portions of fish a week.  

Dr Marc Gunter, the lead researcher from the International Agency for Research on Cancer (IARC), said: “Our research shows that eating fish appears to reduce the risk of bowel cancer and should be encouraged as part of a healthy diet.

“One down fall of the study is that dietary data collected from participants did not include information on fish oil supplement intake. This unmeasured fish oil supplementation may also have an effect on bowel cancer, so further studies will be needed to see if fish or fish oil influence bowel cancer risk.”

Dr Anna Diaz Font, Head of Research Funding at WCRF, said: “This large study adds to the scientific evidence suggesting that consuming fish could reduce the risk of bowel cancer. The biological reasons by which fish consumption potentially lowers risk are not fully understood but one of the theories include specific fatty acids such as omega-3, found almost exclusively in fish, being responsible for this protective effect via their anti-inflammatory properties.”

The authors of the study attempted to test this hypothesis and so also looked at intake of omega-3 in the participants diet and the same correlation was observed; higher omega-3 in the diet reduces the risk of bowel cancer. This supports the theory that omega-3 may be responsible for the potential protective effect of fish against bowel cancer. The study found no link between eating shellfish alone and bowel cancer.

Bowel cancer is the fourth most common cancer in the UK and the cancer with the second highest death rate. In 2015, 43,178 cases of bowel cancer were diagnosed in the country. Around 40% of all cancer cases could be prevented if everyone had healthier lifestyles, said the WCRF, this includes being a healthy weight, doing more exercise and eating a balanced diet.

Rising cases of bowel cancer in young

A separate study added to the evidence suggesting the number of young people developing bowel cancer around the world may be increasing.

The incidence of bowel cancer in younger people has risen by a fifth in a decade, according to a US study published in the journal Cancer

The study by the University of Texas at Austin analysed trends in bowel cancer and examined information from the National Cancer Database registry, which includes more than 70% of new cases in the US.

From 2004 to 2015, the year the most recent data is available, 130,165 patients under 50 and 1,055,598 patients over 50 were diagnosed with bowel cancer. More than half (51.6%) of younger adults being diagnosed when they were in the most advanced stages.

Deborah Alsina MBE, Chief Executive of Bowel Cancer UK, said: “This study further adds to the growing body of evidence that shows more younger people are developing early onset bowel cancer around the world. Although the disease is much more common in those over 50, each year in the UK over 2,500 younger people will be diagnosed.

Source: Clinical Gastroenterology and Hepatology

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