"...Excess iron's role in infectious diseases is now well established, and many recent studies show that it is involved in degenerative brain diseases, such as Parkinson's, ALS (Lou Gehrig's disease), Huntington's chorea, and Alzheimer's disease. Iron is now believed to have a role in skin aging, atherosclerosis, and cataracts of the lenses of the eyes, largely through its formation of the 'age pigment.'
"During aging, our tissues tend to store an excess of iron. There is a remarkably close association between the amount of iron stored in our tissues and the risk of death from cancer, heart disease, or from all causes. This relationship between iron and death rate exists even during childhood, but the curve is downward until the age of 12, and then it rises steadily until death. The shape of this curve, representing the iron burden, is amazingly similar to the curves representing the rate of death in general, and the rate of death from cancer. There is no other relationship in biology that I know of that has this peculiar shape, with its minimum at the age of 12, and its maximum in old age at the time of death.
"One of the major lines of aging research, going back to the early part of this century, was based on the accumulation of a brown material in the tissues known as 'age-pigment.' The technical name for this material, 'lipofuscin,' means "fatty brown stuff." In the 1960s, the 'free radical theory' of aging was introduced by Denham Harman, and this theory has converged with the age-pigment theory, since we now know that the age-pigment is an oxidized mass of unsaturated fat and iron, formed by uncontrolled free radicals."
Dr. Ray Peat
from "Iron's Dangers."