Fats, iodine, vitamin A make a triangle. Beta-carotent is NOT vitamin A, hahaha, lobbyists paid big moolah long time ago, to "allow" carotent to be labelled as vitamin A, haha. Most suffer avitaminosis A subclinically. Eating the wrong fats, not good, so what are the right fats ? haha. Lack of considering all three I'd imagine, is why so many negative reports by some in the past. Lipids, Iodine and the retinoic acid family of molecules...are wonderful stuff !! Longevity depends on soooo much !! Lipids are a huge factor, don't eat the bad ones :)