Oranges...

Oranges are rich in citrus limonoids, proven to help fight a number of varieties of cancer including that of the skin, lung, breast, stomach and colon.
Drinking orange juice regularly prevents kidney diseases and reduces the risk of kidney stones.
Note: drink juice in moderate amounts. The high sugar content of fruit juices can cause tooth decay and the high acid content can wear away enamel if consumed in excess.
According to two studies in Japan eating mandarin oranges reduces liver cancer. This may be due in part to vitamin A compounds known as carotenoids. Oranges are full of potassium, an electrolyte mineral responsible for helping the heart function well. When potassium levels get too low, you may develop an abnormal heart rhythm, known as an arrhythmia.
Oranges are full of vitamin C, which protects cells by neutralizing free radicals. Free radicals cause chronic diseases, like cancer and heart disease. Studies show that the abundance of polyphenols in oranges protects against viral infections. Oranges are full of dietary fiber, which stimulates digestive juices and relieves constipation.
Oranges are rich in carotenoid compounds, which are converted to vitamin A and help prevent macular degeneration.
The flavonoid hesperidin found in oranges helps regulate high blood pressure, and the magnesium in oranges helps maintain blood pressure.
Oranges are full of beta-carotene, which is a powerful antioxidant that protects the cells from damage. Beta-carotene protects the skin from free radicals and helps prevent the signs of aging.
Although oranges are acidic before you digest them, they contain many alkaline minerals that help to balance out the body after they are digested. In this respect, they are similar to lemons, which are one of the most alkaline foods available.
Oranges like all fruits have simple sugars in them, but the orange has a glycemic index of 40. Anything under 55 is considered low. This means as long as you don’t eat too many oranges at one time, they won’t spike your blood sugar and cause problems with insulin or weight gain. Oranges have a wealth of nutrients including vitamin C, vitamin A precursors, calcium, potassium and pectin.