Apples

The one a day "forbidden fruit" habit does more than keep the doctor away.
Apples are a great package, they're full of vitaminC, which we know is a powerful antioxidant, are a good source of dietary fibre and have a low GI, so provide lasting energy."
According to experts, eating apples as nature intended - skin and all - is best for boosting your intake of the vitamins and nutrients that they're renowned for.  Like many vegetable, the skin is where a lot of the nutrients are concentrated.  Infact, a study released last year by Cornell University in New York found that apple's peel contains at least a dozen compounds - called triterpenoids - that either inhibit or kill cancer cells.
Cancer
From cancer, Alzheimer's disease and asthma to heart disease, obesity and diabetes, the humble apple is an illness-fighting powerhouse.  Several studies have linked apple consumption to a reduced risk of cancer - particularly lung cancer by as much as 50 per cent - making them one of the few foods specifically identified for this benefit.  And Italian researchers found that people who eat a least one apple a day have a reduced incidence of several types of cancer including oral, breast, ovarian and prostate.