You’ve always heard the saying, “gum stays in your stomach for seven years”, or “you shouldn’t swim for an hour after eating.” And our personal favorite here at Food University, “an apple a day keeps the doctor away.” But are these common phrases food fact or food fiction?  CNN and Realsimple.com help debunk these 12 health myths. Here are some of our favorites:

An Apple a Day Keeps the Doctor Away.

The truth is: A handful of blueberries a day will keep the doctor away more effectively. Blueberries are a nutritional jackpot, rich in antioxidants and fiber, and they’re also easy to toss into cereal and yogurt. That said, eating a variety of fruits and vegetables is important to prevent many chronic illnesses, such as heart disease, high blood pressure, and diabetes, down the road. (To find out how much earth-grown goodness your child should be getting, enter his or her age, sex, and level of physical activity at fruitsandveggiesmatter.gov.)

Gum Stays in Your Stomach for Seven Years.

The truth is: Your Little Leaguer’s wad of Big League Chew won’t (literally) stick around until high school graduation. “As with most nonfood objects that kids swallow, fluids carry gum through the intestinal tract, and within days it passes,” says David Pollack, a senior physician in the Children’s Hospital of Philadelphia Care Network. And even though gum isn’t easily broken down in the digestive system, it probably won’t cause a stomachache, either.

You Shouldn’t Swim for an Hour After Eating.

The truth is: Splash away. “After you eat, more blood flows to the digestive system and away from the muscles,” says Cohen. “The thinking was that if you exercised strenuously right after eating, that lack of blood would cause you to cramp up and drown.” But that won’t happen. Sears concurs: “You might have less energy to swim vigorously, but it shouldn’t inhibit your ability to tread water or play.”

Warm Milk Will Help You Fall Asleep.

The truth is: Milk contains small amounts of tryptophan (the same amino acid in turkey), “but you would have to drink gallons to get any soporific effect,” says Michael Breus, a clinical psychologist in Scottsdale, Arizona, who specializes in sleep disorders. “What is effective is a routine to help kids wind down,” he says. And if a glass of warm milk is part of the process, it can have a placebo effect, regardless of science.

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You’ve heard it all before: turkey makes you sleepy, sugar makes kids crazy. But are these food-mood myths for real or just real fake? With a little help from the folks at the LA Times, we’re here to set the record straight, once and for all!

1. Turkey makes you sleepy.

False.

This Thanksgiving, when a relative tries to tell you turkey makes you sleepy because of tryptophan, tell ‘em they’re wrong. Turkey, as well as milk, are rich in tryptophan- an amino acid that is often cited as the culprit in after-dinner lethargy. “Each molecule of tryptophan has to compete with many other amino acids in the brain”, says Elizabeth Somer, a registered dietitian and author of “Eat Your Way to Happiness.” So if it isn’t the tryptophan, what makes us so tired after a turkey dinner? “Eating any big meal, especially if you drink alcohol, is likely to make you feel sleepy”, Somer goes on to say. “A Thanksgiving feast will make you feel groggy, but tryptophan isn’t the reason.” Stay away from a food comatose this Thanksgiving and hold off on that second serving of mashed potatoes and stuffing.

2. Sugar makes kids hyperactive.

False.

Seing your child storm through the front door with a pillow case full of sweets is concerning for any parent. How on earth am I going to get my kid to sleep when he’s all hopped up on candy? Well, it’s not the sugar that’s causing this, but really just the excitement and unrestricted environment surrounding the festivities. Robin Kanarek, who directs the nutrition and behavior laboratory at Tufts University in Medford, Mass claims that sugar has nothing to do with how children behave. “The fact that parents expect their kids to bounce off the walls after they eat sweets is what perpetuates the behavior. Moreover, many parents don’t realize that the body can’t tell the difference between the sugar in a glass of apple juice or the sugar in a large cookie.” Kanarek might have a point here, but good luck telling that to some parents…

3. Chocolate brings out good feelings

False (well, for the most part)

What’s not to love about chocolate? It tastes great, enhances mood and is known as an aphrodisiac. Chocolate has many components that can enhance mood, but the chemical effect of them is minimal. “Whatever mood boost chocolate gives you is all in your head- and thats OK”, says Marcia Pelchat, a food researcher at Monell Chemical Senses Center in Philadelphia. “It does have low levels of stimulants, but you can get a lot more from other substances,” she explains. “The caffeine content is very low, so coffee is better for that kind of kick. The sugar might give a temporary lift, but it’s subtle. And the phenylethylamine that people say is supposed to make you feel in love — well, many foods, including salami, are much higher in phenylethylamine.” Chocolate might be able to improve your mood, but the effects are mostly just mental.

4. Omega 3 fatty acids found in fish help depression.

True!

We recently tweeted about the best foods for your heart. Finishing at #1 was salmon- its high dosage of omega 3 fatty acids makes it great for your heart and blood vessels. Turns out, that’s not the only thing omega 3 is good for. Joseph Hibbeln, psychiatrist and acting chief for the Section on Nutritional Neurosciences studied the effects of omega three fatty acids on depression. “These nutrients are as effective as antidepressants in treating people with clinical depression,” Hibbeln says. For those with clinical depression, the recommended dose is three 6-ounce servings of salmon, tuna, herring or sardines each week. Not a fan of seafood? The American Psychiatric Assn. recommends that people with major depression consume a daily omega-3 supplement.