Bowel cancer patients could significantly increase their survival chances by eating oily fish once a week, according to researchers.
The omega-3 fatty acids in sardines, salmon and trout helped supress tumour growth and cut blood supply to cancer cells.
US experts have found that regularly eating small amounts of these beneficial fish after a diagnosis of bowel cancer could cut the risk of dying from the disease by up to 70 per cent.
More than 41,000 people are diagnosed with bowel cancer in the UK every year, making it the country's fourth most common cancer.
The disease kills 16,000 people in the UK every year.
According to the researchers from Harvard Medical School and Massachusetts General Hospital in Boston, their findings needed to be reproduced in further studies in case they were replicated, patients with bowel cancer might benefit from boosting their oily fish intake.
They analysed the health records of 170,000 US citizens monitored for at least a decade, 1,659 of whom developed bowel cancer.
Of those, 561 had died during the study period, and 169 of those deaths were specifically attributable to their cancer.
What was remarkable was that even small amounts of fish oil seemed to make a difference. A normal portion of oily fish contained around 1.8g of omega-3 but just 0.3g a day cut the risk of death within 10 years of diagnoses by 41 per cent.
It suggests that just a few mouthfuls a day, or one or two portions a week might be beneficial.
Those people who upped their intake by a further 0.15g after diagnosis lowered their risk by 70 per cent. However those who cut the amount of fish raised their risk of death by 10 per cent.
Although the researchers said the findings were observational and no firm conclusions could be drawn, they concluded that it provided the first evidence that omega-3 fatty acids could impact bowel cancer survival.
''If replicated by other studies, our results support the clinical recommendation of increasing marine omega-3 fatty acids among patients with bowel cancer,'' said lead researcher Dr Andrew Chan, Clinical and Translational Epidemiology Unit, Massachusetts General Hospital, Boston.