GCXZ

The study did not prove a causal link between eating nuts and longer life, but researchers said their findings backed up previous research on the health benefits of nuts.

They contain unsaturated fatty acids, high-quality protein, fibre, vitamins, minerals, and phytochemicals, all of which "may confer cardioprotective, anti-carcinogenic, anti-inflammatory, and antioxidant properties," they said.

The study, which was sponsored by the International Tree Nut Council as well as the US National Institutes of Health, used data on people's diets, lifestyles and health from two large databases compiled between 1980 and 2010.

They answered detailed questionnaires on a range of foods every two to four years, including estimating how often they ate an ounce – or about a handful – of nuts.

Results published in the New England Journal of Medicine showed that deaths from any cause were reduced by 11 per cent for people who ate nuts once per week, 13 per cent for those eating nuts two to four times per week, 15 per cent in people who ate them five to six times per week, and 20 per cent for those who ate nuts every day.

Dr Charles Fuchs from the Dana-Farber Cancer Institute in Boston, who led the study, said: "The most obvious benefit was a reduction of 29 per cent in deaths from heart disease – the major killer of people in America.

"But we also saw a significant reduction – 11 per cent – in the risk of dying from cancer."

Previous studies have suggested that eating nuts could lower the risk of conditions including heart disease, diabetes and bowel cancer but the new study was the first to examine their effect on mortality among a large group.

The study was not able to distinguish between different types of nut to determine which were the healthiest, but it did show that peanuts, which are in fact a type of bean, had a similar effect on death rates to "tree nuts" including walnuts, hazelnuts, cashews, almonds, Brazil nuts, pecans and pistachios.

The researchers said the findings were consistent with "a wealth of existing observational and clinical trial data to support health benefits of nut consumption on many chronic diseases".

In 2003, the American Food and Drug Administration decided there was sufficient evidence to advise that eating 1.5oz (43g) per day of most types of nut "may reduce the risk of heart disease".