sugar

These soil-dwelling microbes fix nitrogen for specialized plants like legumes in return for sugars and protection.

“If I drink really good tequila and I don’t do any sugar — no margaritas — I can get as drunk as I want, and I’ll have no hangover.”

The result is massive health costs, with sugars linked to obesity around the world.

Although the underlying mechanisms are not fully understood, scientists think that some of the hallmarks of diabetes -- such as high blood sugar, insulin resistance, and inflammation -- may encourage the development of dementia in the brain.

"For this study, we often had to reach out to participants to ask what kind of meat they'd put in their sandwich, or whether their coffee had sugar in it," Dr. Kleinberg explains.