12/10/2002

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Chow Line: Caffeine, carbs work differently in body (for 12/22/02)

Writer:

Martha Filipic
filipic.3@osu.edu
(614)292-9833

Source:

Sharron Coplin

My sister-in-law told me she heard that apples have more caffeine than coffee. I'm suspicious -- can that be true?

Um, no. I hope this doesn't cause one of those never-ending in-law squabbles, but you (and everyone else) should know that there's no caffeine in apples.

Maybe your sister-in-law heard that apples can give you a pretty good energy boost. A medium-sized apple averages 20 grams of carbohydrates -- not nearly as much as in a sugary snack, but the apple would certainly be a more nutritious choice than, say, a candy bar. And this year, you could get even a bigger boost from locally grown apples: The Midwest's dry summer decreased apples' moisture content, which concentrates the sugars in each fruit, making them delightfully sweet. Who wouldn't feel refreshed munching on a crisp, sweet apple?

Still, that's not the same kind of boost people get from caffeine. They work in totally different ways.

Simply put, food boosts your energy by helping form ATP (adenosine triphosphate). Cells use ATP whenever they need energy, whether it's chemical energy to store for later use; mechanical energy used in muscle movement; electrical energy for nerve transmissions; or osmotic energy to balance sodium, potassium and other ions within the cell. When ATP is tapped for use, it breaks down. It's in that breakdown that energy is released, from the bonds that hold ATP together. ATP continually is broken down and re-formed in the body.

Coincidentally, adenosine (the "A" in ATP) also shows up in the explanation for how caffeine works. Again, simply put: When adenosine binds to receptors in the brain -- as cyclic adenosine monophosphate, or cAMP, it calms nerve cell activity and makes us drowsy. Caffeine happens to be structured very much like cAMP and can bind to those receptors. When it does, it blocks cAMP and keeps us from getting tired. Other factors also play a role, but already you can see that caffeine and carbs play very different roles in energy balances in the body.

Chow Line is a service of Ohio State University Extension and the Ohio Agricultural Research and Development Center. Send questions to Chow Line, c/o Martha Filipic, 2021 Coffey Road, Columbus, OH 43210-1044, or filipic.3@osu.edu.

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Editor:

This column was reviewed by Sharron Coplin, registered dietitian and Ohio State University Extension nutrition associate in the College of Human Ecology.