Since I can’t see why people would be upset to know how diet can affect your skin’s ability to defend against radiations.

A lot of your downvotes probably come from people misinterpreting your message as some woo woo bunk about replacing sunscreen with a proper diet and you won't get sunburned, which clearly isn't what you're saying. However, its very easy for small, flippant comments to come across with wildly different connotations from the reader. Not really sure how to get around that, outside of way too much context.