Spot the Error.

Most of us do not yet understand that news is to the mind what sugar is to the body

The sentence is grammatically correct, with no spelling, punctuation or grammar errors. It compares news and sugar, stating that news affects the mind similarly to how sugar affects the body. The use of "to" is correct in both instances: "sugar is to the body" and "news is to the mind". The phrase "do not yet understand" is also grammatically correct and conveys the meaning that most people still have not realised or comprehended the comparison being made. Therefore, there is no error in the sentence.