Sugar is bad for you, right? Everybody knows that. But it's very good for one thing--cancer cells. According to Science Magazine, cancer tissues have extra sugars that bind to the protein Siglec-9 on natural killer cells.
In doing so, they quiet the immune response and make the body less able to fight off the deadly enemies. To our defense system, cell-surface sugars are a molecular fingerprint--and a type of Harry Potter-like invisibility cloak--telling a roving immune cell, "This one's OK. Move along." Certain pathogens, such as the bacteria that cause gonorrhea or streptococcal infections, have taken advantage. They coat themselves with sialic acids to hide from the immune system.