Confused Apostate

Sunburn is a fat going rancid inside you, and the compound it produces has a name. 4-hydroxynonenal. An aldehyde. Measurable, published, sitting in the literature for forty years. It does not come from nowhere. It is a breakdown product of omega-6. Specifically linoleic acid and the arachidonic acid your body makes from it. Linoleic acid has two double bonds. Every double bond is a weak point where oxygen gets in. Saturated fat has none. Monounsaturated has one and it is hard to reach. Your cell membranes are built from whatever fat you have been eating, on a turnover of roughly two years. Ultraviolet light hits the skin and strips a hydrogen off one of those weak points. That starts a chain reaction called lipid peroxidation, and a chain reaction does not need more light to continue. It propagates on its own. The chain breaks the fatty acid apart. Out come 4-hydroxynonenal and malondialdehyde. Those aldehydes cross-link proteins, damage DNA and trigger the inflammatory cascade. The redness, the heat, the swelling, the peeling. That is the immune response to the wreckage, not the sunlight itself. More linoleic acid in the membrane means more fuel in the fire. Linoleic acid in American body fat ran at about 9 per cent in 1959 and reached 21 per cent by 2008. Your grandfather worked outdoors all day in a vest and came home brown, on membranes built from lard, butter and dripping. He was less flammable, and nobody had told him he was doing anything brave. Four grams of omega-3 a day let volunteers take 36 per cent more UV before burning. Fish oil cut the inflammatory signal in irradiated human skin by more than 60 per cent. Sunlight is not the accelerant. It is the ignition. Fifty years of advice about what to spread on your skin, and not one word about what you built it out of.