Monday, August 17, 2009

Free Radicals in Death and Health

An interesting section in Nick Lanes book bears comment. In the 1950's Denham Harman, a chemist with the oil industry, proposed that free radicals may attack critical biological molecules. This would ultimately lead to ageing and disease. Much in the media today and in CAM community still touts this basic idea. We have all heard of foods that have antioxidants and supposedly lead to better and longer health. A lot has changed in the half century since that idea was first put forth. Several things Harman did not or could not have known. Free radicals are used by cells to optimise respirations and as a danger signal. They don't attack proteins and DNA at random, but activate or disable the activity of hundreds of proteins and genes. They are central to the cell physiology. So antioxidants actually do as much harm as good. Antioxidant levels in the blood are strictly controlled within tight limits. Large doses of them are simple excreted or not absorbed in the first place. Antioxidants levels remain at a roughly constant level. Another factor is free radicals are released from mitochondria via an enhance leak from them when programmed cell death is signaled. It is this that determines longevity and has been shown experimentaly in different animals. To find out more get and read Nick Lanes book "Life Ascending; The Ten Great Inventions of Evolution."
Skeptical DoDo

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