A daily handful of any type of nuts slashes the risk of heart disease and cancer, Britain's biggest killers.
Just 20 grammes - 0.7oz- of walnuts, almonds, hazelnuts, cashews, pistachios, pecans, Brazil nuts and peanuts cuts risk of coronary heart disease by nearly 30 per cent and stroke by seven per cent.
They also cut the risk of cancer by 15 per cent and the risk of premature death by 22 per cent.
The snack also reduced risk of dying from respiratory disease by about a half, diabetes by nearly 40 per cent and deaths from infectious disease by 75 per cent.
Scientists said a handful was all that was needed as there was little evidence eating more than 20g per day further improved the protection against diseases.
And the health benefits of nuts, whether tree nuts such as walnuts or Brazil nuts and peanuts were down to their nutritional value.
While the intake of both peanuts and tree nuts was associated with a reduced risk of coronary heart disease, cardiovascular disease, and mortality only peanuts were associated with reduced risk of stroke, while tree nuts was associated with reduced cancer risk.
Previous studies found growing evidence a high intake of nuts was linked to reducing the risk of coronary heart disease and death but their impact on risk of stroke or overall cancer risk was unclear.
So Imperial College London and the Norwegian University of Science and Technology scientists analysed 29 published studies from around the world.
These involved up to 819,000 participants, including more than 12,000 cases of coronary heart disease, 9,000 cases of stroke, 18,000 cases of cardiovascular disease and cancer, and more than 85,000 deaths.
While there was some variation between the populations , the sexes and regions, nut consumption was associated with a reduction in disease risk across most of them.
Co-author Dr Dagfinn Aune at Imperial's School of Public Health said: "In nutritional studies, so far much of the research has been on the big killers such as heart diseases, stroke and cancer, but now we're starting to see data for other diseases.
"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.
"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."
However he warned people should avoid peanut butter as they can be high in sugar or salt.
But if everyone ate at least a handful of nuts a day 4.4 million premature deaths globally could be avoided.
Dr Aune added: "For specific causes of death, we estimated that 1.19 million deaths due to coronary heart disease, 469,000 due to cancer, 1.07 million due to respiratory disease, and 138,000 due to diabetes may be caused by a nut intake below 20 grammes per day.
"In conclusion, our results provide further evidence that nut consumption may reduce the risk of coronary heart disease, stroke, cardiovascular disease, total cancer, and all cause mortality, and possibly mortality from diabetes, respiratory disease, and infectious disease. I
"These findings support dietary recommendations to increase nut consumption to reduce chronic disease risk and mortality."
The study was published in the journal BMC Medicine.