If you're looking for that early morning or late afternoon pick-me-up, that coffee or soda you rely on may not give you the boost you need.
A new study shows that people who drink a lot of caffeine ultimately develop a tolerance to its ability to increase alertness. That means if you need more get-up-and-go, then you need to drink more caffeine than you normally do.
Study results also suggest that if you regularly consume caffeine and give it up for a while, you'll start to experience withdrawal symptoms. In that case, you'll need to drink the amount you regularly drink in order to feel normal again.
While we may be worried that our daily intake of caffeine won't give us the jolt we crave after all, some experts warn against rushing to judgment.
"I don't think a conclusion can be drawn based on the results of one study," said Keri Gans, a nutritionist and spokesperson for the American Dietetic Association.
"I think it's too soon to call it a myth," she added.
Still, the possibility that one of the most widely held food beliefs may indeed be untrue may have some people wondering about whether some other things we've heard about the food we eat are fact or fiction.
At the first appearance of a pimple, many people are quick to blame the food they ate recently, especially if it's greasy and fattening.
Nutrition experts say that's not true.
"The myth probably came about because there's grease in certain foods and oily skin causes acne, so someone just kind of made the connection," said Karen Ansel, also a spokesperson for the American Dietetic Association.
In fact, they say there's no link at all between any specific food and acne.
"There's really no research that's found a connection between diet and acne. It's not there," Gans said.
"The take home point is that acne is hereditary and hormonal. It's an internal thing you really can't control," said Heidi Skolnik, a New Jersey-based nutritionist and fitness instructor.
But there are some studies that do suggest a connection between high glycemic index foods and acne.
"High sugar foods can cause acne, because foods that have a high glycemic index increase insulin levels, and that makes your body produce androgens, which cause acne," said Ansel.
As it turns out, everyone's favorite comfort food does have health benefits -- but only the dark kind. Cocoa contains flavonoids, which can help lower blood pressure.
But that doesn't mean you should go out and indulge your sweet tooth by eating lots of dark chocolate. The bars of chocolate you see in the supermarket usually don't contain enough cocoa to be really heart-healthy.
"You've got to have something that has a substantial amount of cocoa in it, not your standard dark chocolate bars," said Ansel.
The kind that is good for you is extremely dark and can taste very bitter. There is a way you can get the benefits from it, though.
"You can take a little and add it to your coffee," said Ansel.
But if you've just got to have your dark chocolate fix, nutritionists say there's no reason you can't.