Eating fish three times a week cuts the risk of bowel cancer by 12% ‘by reducing inflammation in the body’
- Applies to all types of fish; eating just oily varieties cuts the risk by 10%
- Fish contains fatty acids that are thought to reduce inflammation in the body
- Inflammation may trigger cancer by damaging DNA; it then fuels its growth
Eating fish three times a week cuts the risk of bowel cancer, research suggests.
A study found those who consume three or more portions are 12 per cent less likely to develop the disease than those who have just one serving.
The finding applied to all types of fish, but those who just eat oily varieties, like salmon or mackerel, only cut their risk by 10 per cent.
Fish contains fatty acids that are thought to reduce inflammation in the body, the University of Oxford researchers claim.
Inflammation may trigger cancer by damaging DNA, past studies suggest.
The inflammatory process also produces molecules called cytokines, which stimulate the growth of blood vessels that ‘feed’ a tumour.
Eating fish three times a week cuts the risk of bowel cancer, research suggests (stock)
The research was a collaboration between the University of Oxford and the International Agency for Research on Cancer (IARC) in Lyon.
It was led by Dr Marc Gunter, head of the nutritional epidemiology group at the IARC.
‘Our research shows eating fish appears to reduce the risk of bowel cancer and should be encouraged as part of a healthy diet,’ Dr Gunter said.
Bowel, or colorectal, cancer is the fourth most common cancer in the UK, with around 42,000 people being diagnosed every year, Bowel Cancer UK statistics show.
And in the US, bowel tumours are the third most diagnosed type of cancer, according to the American Cancer Society.
Some 145,600 Americans are expected to be told they have the condition this year.
Experts predict around 40 per cent of cancer cases could be avoided if people quit smoking, lost weight and ate better.
To uncover whether fish has any benefits, the researchers analysed the diets of 476,160 people who completed food questionnaires.
After an average follow-up of nearly 15 years, 6,291 of the participants had developed bowel cancer.
WHAT IS BOWEL CANCER? AND WHAT ARE ITS SYMPTOMS?
Bowel, or colorectal, cancer affects the large bowel, which is made up of the colon and rectum.
Such tumours usually develop from pre-cancerous growths, called polyps.
- Bleeding from the bottom
- Blood in stools
- A change in bowel habits lasting at least three weeks
- Unexplained weight loss
- Extreme, unexplained tiredness
- Abdominal pain
Most cases have no clear cause, however, people are more at risk if they:
- Are over 50
- Have a family history of the condition
- Have a personal history of polyps in their bowel
- Suffer from inflammatory bowel disease, such as Crohn’s disease
- Lead an unhealthy lifestyle
Treatment usually involves surgery, and chemo- and radiotherapy.
More than nine out of 10 people with stage one bowel cancer survive five years or more after their diagnosis.
This drops significantly if it is diagnosed in later stages.
According to Bowel Cancer UK figures, more than 41,200 people are diagnosed with bowel cancer every year in the UK.
It affects around 40 per 100,000 adults per year in the US, according to the National Cancer Institute.
Results – published in the journal Clinical Gastroenterology and Hepatology – revealed eating 359.1g of any type of fish a week reduced the risk of bowel cancer by 12 per cent.
This was compared to consuming less than 63.49g. A typical portion of fish is around 100g.
Eating 123.9g of oily fish alone every seven days lowers the risk by 10 per cent.
Oily fish contains the fatty acid omega-3, which has been shown to inhibit the growth of cancerous and pre-cancerous cells but not healthy ones.
Shellfish was not found to have any effect on a person’s bowel cancer odds, the study adds.
‘Consumption of fish appears to reduce the risk of colorectal (bowel) cancer and should be encouraged as part of a healthy diet,’ the authors wrote.
The researchers acknowledge, however, that the potential benefits of fish supplements are unclear.
‘One downfall of the study is dietary data collected from participants did not include information on fish oil supplement intake,’ Dr Gunter said
‘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.’
The study was funded by the World Cancer Research Fund (WCRF).
Dr Anna Diaz Font, head of research funding at the 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 includes specific fatty acids such as omega-3, found almost exclusively in fish.
‘[These may be] responsible for this protective effect via their anti-inflammatory properties.’
Lisa Wilde, director of research and external affairs at Bowel Cancer UK welcomed the study but called for further research.
‘Making simple changes to your lifestyle can help stack the odds against bowel cancer,’ she said.
‘Including wholegrains, fibre and fish in your diet; being of a healthy body weight; having regular physical activity; avoiding processed meats and limiting red meat, can all make a real difference.’
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