Much of the cell damage in human body is caused by highly destructive chemical group known as free radicals. 
These are the products of oxidation, a process which occurs naturally as we breathe. The modern civilization has caused more unnatural elements in the air, thus more free radicals than ever. In small quantities, free radicals can fight bacteria and viruses; in larger quantities they encourage the aging process and cause damage to our cells.
Fortunately, these can be battled by antioxidants – the ACE vitamins (vitamin A in the form of beta carotene, vitamin C, and vitamin E), the minerals selenium and zinc, and to a lesser extent manganese and copper. Antioxidants protect other substances from oxidation. Many experiments have shown that additional antioxidant vitamins-such as 2,000mg. of vitamin C and 400 mg. of E daily – can significantly reduce the incidence of heart attacks, strokes, and other diseases, and slow down the process of aging.