A paper by Nicola Veronese studied 4,440 people (ages 45-79) over an 8 year period to see if the quantity of potato products ate by the participants had an effect on mortality.
During the 8 years, 236 of them died. A study of their eating patterns did not show any significance to the quantity of potato foods, but did show that people who regularly ate fried potato foods (such as chips, hash browns, crisps, wedges) were twice as likely to die in that period than any other people.
The paper does not speculate as to why this would be so, but I can make two guesses: trans fats, and free radicals.
Potatoes are usually fried in fatty products, which can contain trans fats. There is a myth that trans fats are produced by the very act of frying, but that’s all it is – a myth.
Potatoes don’t contain much fat at all. They are mostly carbohydrate. When you fry them, though, they absorb the oil, and therefore the oil’s fats, including trans fats.
Trans fats kill people. Denmark banned the sale of products containing trans fats in 2003, which caused a drop of 70% in cardiovascular deaths measured between 1985 and 2009.
Some restaurants claim that their chips are trans-fat-free. When the Indiana Academy of Sciences tested this claim, they found that most of these claims were false.
Free radicals are molecules that are formed when oil molecules are heated and start ripping atoms from each other. This forms molecules that are “radical”, in that they have an unpaired electron which they try to resolve by attaching to other molecules.
When radicals are free in the body, they can cause damage. Anti-oxidants can mitigate this damage by attaching to the radicals before they do damage, but if the radicals outmatch the anti-oxidant protection, then damage can occur which is cumulative over your lifetime.
In short, if you’re working on your longevity, baked chips are better for you than fried chips.