There seems to be some truth in the old saying: "An apple a day keeps the doctor away."

A new study in the Chinese population said Wednesday that people who eat fresh fruit on most days are at lower risk of heart attack and stroke than people who rarely eat fresh fruit.

The findings, published by the New England Journal of Medicine, came from a seven-year study of half a million adults in China, where fresh fruit consumption is much lower than in countries like the UK or the United States.

Researchers from the University of Oxford and Chinese Academy of Medical Sciences conducted a large, nationwide study of 500,000 adults from 10 urban and rural localities across China, tracking health for seven years through death records and electronic hospital records of illness.

The participants did not have a history of cardiovascular diseases or anti-hypertensive treatments when they first joined the study.

The study found that eating fruits, mainly apples or oranges, was strongly associated with many other factors, such as education, lower blood pressure, lower blood glucose, and not smoking in China.

But, after allowing for what was known of these and other factors, a 100-gram portion of fruit per day was associated with about one-third less cardiovascular mortality and the association was similar across different study areas and in both men and women.

"The association between fruit consumption and cardiovascular risk seems to be stronger in China, where many still eat little fruit, than in high-income countries where daily consumption of fruit is more common," study author Huaidong Du of the University of Oxford said.

Also, fruit in China is almost exclusively consumed raw, whereas much of the fruit in high-income countries is processed, and many previous studies combined fresh and processed fruit, said Du.

Senior author Zhengming Chen, professor at the University of Oxford, noted that it's difficult to know whether the lower risk in people who eat more fresh fruit is because of a real protective effect.

"If it is, then widespread consumption of fresh fruit in China could prevent about half a million cardiovascular deaths a year, including 200,000 before age 70, and even larger numbers of non-fatal strokes and heart attacks," Chen added.