An Australian study proves the truth of the old saying, "An apple a day keeps the doctor away." Researchers at the University of Western Australia found that eating a small apple every day cut the risk of dying early by 35 percent.

Researchers examined the health habits of 1,456 women aged 70 to 85 years for 15 years. They found that women who ate more than 100 grams of apple a day (the equivalent of a small apple) lived longer than women who ate an average of less than 5 grams a day.

While the study found that a variety of fruits provided health benefits, apples scored particularly high because of the fiber and flavonoids found in their skin. Flavonoids are a type of antioxidant that help prevent cell damage.

In addition to flavonoids, apples also contain vitamin C, potassium, and magnesium.

Researcher Dr. Jonathan Hodgson said the reduction in mortality may be due to a combination of factors, such as the interaction between flavonoids and fiber, that aren't yet understood.

In an earlier study, Dr. Hodgson found that apples improved heart health. Men and women were given a meal that was enriched with apple flavonoids or a meal that wasn't enriched.

"We found that flavonoid-rich apples improve blood vessel relaxation and enhance nitric oxide status — the molecule that causes blood vessel relaxation," Hodgson said. "A reduced ability of the blood vessels to relax may cause high blood pressure and heart disease."

The earlier study found that the Pink Lady variety of apple was highest in flavonoids.

"We now know that apples have the potential to contribute to a direct and measurable effect on human health," he said.

The current study is published in the British Journal of Nutrition.