A handful of nuts a day can slash your risk of heart disease and cancer.
Eating just 20 grams of nuts every day could reduce the chances of dying early by more than a fifth, scientists found.
Nuts, particularly walnuts, sunflower seeds and pecans, are high in antioxidants, thought to protect the body against cell damage.
Peanuts – technically a legume – are so healthy that a review suggests even peanut butter could help us live longer, although the sugar and salt it contains may cancel out some benefits.
An analysis of 20 studies by Imperial College London found people who ate a daily ounce of nuts slashed their risk of coronary heart disease by almost a third and their cancer risk by 15 per cent.
The findings suggest they may also prevent people dying from respiratory disease and diabetes, although there is less evidence.
Co-author Dr Dagfinn Aune, from the School of Public Health at Imperial, said: ‘We found a consistent reduction in risk across many different diseases, which is a strong indication that there is a real underlying relationship between nut consumption and different health outcomes. It’s quite a substantial effect for such a small amount of food.’
Previous studies have suggested that nuts protect the heart and prevent premature death, but there had been little evidence on cancer risk or other disease.
The review highlights that walnuts may be particularly good at warding off cancer, and peanuts at reducing the risk of stroke.
The handful of nuts a day can include tree nuts, defined as dry fruit containing one seed within the ovary wall which becomes hard at maturity. These include walnuts, almonds, hazelnuts, cashews, pistachios and pecans.
However Brazil nuts, which are actually seeds, and peanuts, classified as legumes, were incorporated within the studies as they have similar nutritional properties.
Despite being high in fat, all these nuts are healthy because they contain poly-unsaturated fat, while also packing in fibre, magnesium and vitamin E. It is believed they protect against heart and blood vessel disease by helping the body break down cholesterol and cutting the body’s resistance to insulin.
The nuts in the bottom of Christmas stockings this month may also reduce cancer risk by helping the body develop new blood vessels and maintaining cells.
An average of at least 20 grams of daily nut consumption was found by the review to cut the odds of dying from respiratory disease almost in half, and cut diabetes risk by nearly 40 percent, although the researchers noted more data is needed.
There may be no need to eat any more, as the researchers found little evidence of further improvement in health by consuming above the 20 grams.
Dr Aune said: ‘Nuts and peanuts are high in fibre, magnesium, and polyunsaturated fats - nutrients that are beneficial for cutting cardiovascular disease risk and which can reduce cholesterol levels.
‘Some nuts, particularly walnuts and pecan nuts, are also high in antioxidants, which can fight oxidative stress and possibly reduce cancer risk.
‘Even though nuts are quite high in fat, they are also high in fibre and protein, and there is some evidence that suggests nuts might actually reduce your risk of obesity over time.’
The study, led by researchers from Imperial College London and the Norwegian University of Science and Technology, is published in the journal BMC Medicine.