Q. Whenever my sister has a low-glycemic episode (she has a pre-diabetic condition), we always give her a glass of orange juice. So, why isn’t that good for everyone?

A. As you know, a pre-diabetic condition indicates that a person tends to have higher than normal blood sugar levels but has not yet been diagnosed with type 2 diabetes. If her blood sugar falls too low—that can be dangerous to one’s brain function—drinking a glass of orange juice typically raises the blood sugar. In individuals without links to diabetes, the orange juice will also raise blood sugar. They are better off eating an orange. The whole fruit contains fiber and other ingredients that help to prevent a sugar spike. Blood sugar highs and lows are not good for the brain. Think about riding a roller coaster that you do not enjoy. Well, your brain is riding a roller coaster that it does not enjoy.