Sure, you know you're supposed to eat well to live a long and healthy life. But what do we really know about how the foods you eat affect how you feel right now? Can red wine give you a headache, does candy make you and the kids spin out of control, and will pizza really make your face break out?
Yes and no. Experts say that when it comes to eating for everyday wellness, sometimes the myths about how some foods affect health may be more powerful than the truth.
In fact, researchers may never be able to definitively separate the effects of the food from other factors to prove or disprove many of these common myths.
Just take sugar, for example.
"A lot of people think sugar causes hyperactivity, but it's actually the circumstances in which it's given in large doses like at a fun party, Halloween, or a birthday that causes hyperactivity," says Nelda Mercer, RD, spokeswoman for the American Dietetic Association. "The hyperactivity link simply hasn't been proven."
'Oh My Aching Head'
Many people avoid also certain foods such as chocolate or red wine because they're afraid it's going to give them a headache.
However, headache expert Seymour Diamond, MD, director of the Diamond Headache Clinic in Chicago, says several studies have unequivocally shown that there is no link between food and headaches. But that doesn't mean the myth still won't hold true for some people, especially those who suffer from recurring migraine headaches.
"I've been doing this for almost 40 years, and I believe people. And people routinely tell us about certain foods triggering migraines," Diamond tells WebMD. "But only about 30% of migraineurs are really sensitive to anything."
The National Headache Foundation recommends that people who experience recurring headaches keep a diary of foods eaten before migraine attacks to determine any possible food sensitivities. Foods frequently reported as headache triggers include:
Diamond says alcohol can also trigger a headache, as anyone who has suffered a hangover after drinking too much can attest. That's because alcohol causes blood vessels to widen, causes dehydration, and even can decrease your blood sugar, all of which can lead to a headache. In addition, certain drinks that have been aged or processed in a flask or barrel, such as red wine, may also contain certain byproducts that can cause headaches.
'But It'll Make Me Break Out'
What teenager hasn't been told to stay away from pizza or other greasy foods because it'll make their face break out with pimples?
But the American Academy of Dermatology says the truth is that extensive scientific research has yet to find a connection between diet and acne. In other words, foods don't cause breakouts.
Dermatologist Doris Day, MD, says some studies are being done that are starting to show that there might be something to the food-acne link, but the problem is that it's a difficult link to prove.
"The question is, do you eat certain foods because you're stressed, and that stress is the same thing that causes acne?" says Day, assistant professor of medicine at New York University. "Or around your period when you want to eat chocolate. ... Is it the hormones that are creating those cravings that are also creating the acne, or is it the food itself?"
Day says that until researchers can prove otherwise, it's best to follow your gut.
"You know your own body, and you know what happens to you when you eat certain things," says Day. "So that's true for you, and you need to avoid those triggers."
Day says that some people may also confuse food-related flare-ups of a skin condition called rosacea with acne. Rosacea is a skin disease that can cause redness and swelling, usually on the face. Spicy foods, hot drinks, and alcoholic beverages are known to cause flare-ups of this condition.
'It'll Help You Sleep'
A warm glass of milk before bed may soothe your nerves, but it won't necessarily send you off to dreamland.
"There is no scientific data that suggests that bananas, turkey, or any of those high tryptophan foods makes you sleepy," says Roth, director of research at Henry Ford Hospital Sleep Disorders and Research Center in Detroit. Tryptophan is a chemical found in milk and other foods that some believe has sleep-inducing effects.
But Roth says foods and drinks containing alcohol or caffeineare known to affect the quality of sleep a person gets. Many people may not realize how much caffeine they get during the course of a day because they only consider coffee or tea as sources, but soft drinks and chocolate also contain significant amounts of caffeine.
Alcohol is often thought of as a sedative, but although it may help people fall asleep faster, the quality of sleep suffers as the number of sleep disturbances increases with alcohol use.
Researchers say food and sleep are also linked in another way -- eating too much of any food or eating too late can make it harder to fall or stay asleep.
"I know from personal experience that if I eat too late, I can't sleep," says dietitian Mercer. "Many people who aren't used to eating after eight o'clock may find it difficult because they're too full to sleep."
Going to bed on a full stomach can also cause gastrointestinal discomfort, and propping yourself on several pillows may be necessary to let gravity help food make its way down to where it needs to go.