In a sense, the generation of a free radical is starting point of the aging process. When a cell in the hypothalamus gets damaged, then it no longer sends an appropriate signal to the pituitary gland to release growth hormone, or luteinizing hormone (which in turn leads to lower testosterone levels).
Likewise, a damaged cell in the testicles cannot respond as well to the LH signal, which in turn also contributes to the age-related decline in testosterone levels. This occurs in many of our important signaling tissues and together creates the changes of aging. This process causes the aging process in non-signaling tissues as well. For example, cataracts are the result of free radical damage to the molecules in the lens of the eye; collagen and elastin in the skin are damaged by free radicals generated by sun damage.
Maintaining good levels of antioxidants has been shown in many studies to decrease the incidence and severity of the diseases of aging. Here are a few of the most popular antioxidants- vitamins, especially vitamin c and vitamin e, garlic, omega-3, selenium, and lycopene. Although vitamins can definitely add the extra boost we may need, some of the richest sources are found through food intake and maintaining a balanced diet.