Eating plenty of oily fish like salmon or mackerel can slash the risk of a premature death by up to a third, according to new research.
A study of 2,500 older people found those who had the highest amounts of omega-3 were 34 percent less likely to die within the next seven years.
They were also 39 percent less likely to suffer a heart attack or stroke.
The fatty acids – found in oily seafood such as salmon, mackerel and sardines – were a better predictor of good health than cholesterol levels.
Scientists found those who had the highest amounts of omega-3 were 34 percent less likely to die in that time
Lead author Dr William Harris, of the University of South Dakota, said: ‘We all know the serum cholesterol level is a major risk factor for cardiovascular disease.
‘Since the latter is a major cause of death in the Western world, it would be reasonable to expect a high cholesterol level would portend higher risk for premature death. This did not turn out to be the case here.
‘When baseline serum cholesterol levels were substituted for the Omega-3 Index in the same multi-variable models, the former was not significantly associated with any of the tracked outcomes whereas the latter was related to four of the five outcomes assessed.’
The study funded by the US National Institutes of Health found a diet rich in oily fish was associated with a lower risk for heart attacks, strokes, coronary heart disease and deaths from all other causes.
This would suggest a wide spectrum of beneficial actions of the key omega-3 acids EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid).
Dr Harris said their actions in the body are not just linked with one pathological process, such as a build up of plaque in the arteries.
The study published in the Journal of Clinical Lipidology analysed the value of measuring blood levels of EPA and DHA to assess an individual’s risk for developing certain diseases.
It used a scale known as the ‘omega-3 Index’ to measure levels of the fatty acids in the red blood cells of participants in the Framingham Heart Study which has followed residents of the Massachusetts town since 1948.
Dr Harris said: ‘Those in the highest compared to those in the lowest fifth had a 34 percent lower risk for stroke or heart attack.
‘When total cholesterol was compared with the omega-3 Index in the same models, the latter was significantly related with these outcomes, but the former was not.’
He added: ‘The causes of death most strongly associated with the omega-3 Index were non-cardiovascular disease and non cancer, in other words, ‘other’ causes.’
All individuals were free of known cardiovascular disease at the outset, when they were aged 66.
The researchers mainly focused on total mortality, or death from any cause, but also tracked death from cardiovascular disease, cancer and other illnesses.
In addition, they reported the associations between omega-3 Index levels and a risk for any heart attack or stroke, fatal or not.
The participants were followed until they were about 73, with lifestyle factors such as alcohol consumption and smoking and socioeconomic status that may have affected the results taken into account.
Dr Harris said the link between higher omega-3 blood levels and lower risk for death has been reported in at least three other studies.
But what was unique about the latest study published in the Journal of Clinical Lipidology was the comparison between blood cholesterol and omega-3 levels, two ‘risk factors’ for heart disease.
Dr Harris said future studies are required to try to replicate the finding and to determine if it is time to begin including the omega-3 Index in routine blood screens along with cholesterol and glucose.
Omega-3 has previously been found to be high in people who live longest. It is believed to reduced inflammation in the brain, cardiovascular system and other cells.
The fats are essential for brain development both in the womb and in early childhood. They are considered so important they are now added to baby milk formula.
A healthy diet should include at least two portions of fish a week, including one of oily fish. Most of us aren’t eating this much. A portion is around 140g (4.9oz).