Apples, to me, are like the forgotten anti-oxident. It seems blueberries and cranberries (and the suddenly famous acai-berry) make it to the top of every anti-oxident, anti-cancer, pro-health, super foods list, but apples could easily be considered just as good.
The "apple a day keeps the doctor away" rhyme likely stems (no pun intended) from the apple's contribution to digestive regularity. They are a good sorce of both "soluble fiber" and "insoluble fiber" which means they boost immunity and help with regularity.
Also, the juice in apples helps kill bacteria that leads to tooth decay.
Washington, the state where I live, is the biggest producer of apples in the US so I encourage you to eat lots of apples.
In addition to the benefits described in the first post, apples are also good for regulating your blood sugar. This is beneficial to keeping you feeling good throughout the day (no low blood sugar "crashes"). Apples have been found in some studies to reduce the amount of fat in a person's blood as well.
Second pohnpei's home state plug in the post above, as I live in the same state not far from him, right in the middle of the Yakima Valley apple country. Apples are a great source of fiber, help to keep your gums and teeth healthy, average about 80 calories and have elements of natural appetite suppressant too. The skins are chock full of vitamins too.
Eating apples is not only tasteful but it is also a good habit for the health.
The apple is recommended to be eaten with skin, since in this part is found 2 times the amount of vitamin C and pentatonic acid than in it's pulp.
The apple is increasing the gastric secretions and if it is eaten with skin has a mild laxative effect, but if it's eaten without skin, it fights against children's diarrhea.
The apple acts like a calmant of the nervous system if it's eaten before going to bed.