We all know that an apple a day keeps the doctor away – but which type of apples helps the most? According to Canadian researchers, that distinction belongs to Red Delicious, Northern Spy and Ida Red. Of the eight popular varieties of the fruit analyzed, these three pack the greatest wallop of disease-fighting antioxidants, they say.

Researchers have long known that apples are a good source of antioxidants, a group of chemicals that scavenge and neutralize unstable molecules called free radicals. Free radicals, which can wreak havoc on cells and tissues, appear to play a role in the onset of heart disease and prostate, colon and other cancers.

Polyphenols — phytochemicals that act like astringents — are major sources of antioxidants in apples, but which polyphenols are most active in the fruit has perplexed scientists. The researchers found:

– polyphenols were five times more prevalent in the skin than the flesh of the apples.

– two polyphenols, epicatechin and procyanidin B2, were the greatest contributors to total antioxidant activity of the apples.

– Red Delicious apples had two times more antioxidant activity than Empire apples, which had the least activity of any of the apples studied.

Three other recent studies by researchers at Cornell University offer plenty of other reasons to eat more apples. In rats, quercetin – another potent antioxidant abundant in apples –– appears to protect brain cells against oxidative stress, a process associated with Alzheimer’s and other neurodegenerative disorders. Antioxidants found in apple extracts could also potentially lower “bad” cholesterol by stimulating the production of LDL receptors in the liver, which help remove cholesterol from the blood. Finally, rats exposed to a known carcinogen and then fed the human equivalent of up to six apples a day were up to 44% less likely to develop breast tumours.

American Chemical Society, May 20, 2005