By Dr. Brian McDonough, Medical Editor

PHILADELPHIA (CBS) – Here is a great argument for eating plenty of fruits and vegetables.

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We know an apple a day was good for you – but now we know exactly how good. A single daily serving of fruits or vegetables is linked to a 5% lower risk of dying early – from any cause.

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Think about that. All you have to do is add a single serving every day.

But even more interesting – each fruit or vegetable that you add to your daily intake is tied to a 5 percent additional drop in that risk, up to five servings a day.

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The information is from the NIH and Harvard – two very reliable sources.