I think all of the degenerative diseases of aging will be minimized by a good diet. We get our vitamins and micronutrients from fruits and vegetables in a balanced diet. 1 don't think it's the whole story, but it will be a major factor in aging and therefore in all of these degenerative diseases. It's inexpensive insurance, and telling people to take a multivitamin is pretty conservative advice. A little extra vitamin E and C is more likely to help than harm, in my view - perhaps in the range of 400 units of vitamin E and 250 mg of vitamin C, but this is still somewhat controversial.
Beta carotene is probably better to get from fruit and vegetables.
But for anyone who wants to take an additional small amount, that's probably all right. Eventually we will. But that's why some people feel that you shouldn't just be taking vitamins without eating fruits and vegetables. Eventually we also will determine proper dosages for nutritional supplements, and I suspect it will be useful to take more than we're getting now. People who eat more fruits and vegetables get half the lung cancer per given amount of smoking compared with the people who eat less.