7 Health-Food Myths Your Mom Got Wrong (and 3 Times She was So, so Right)

Of all our cultural myths and misunderstandings, food fallacies seem to run especially rampant. We absorb "guidance" from our families ("Eat your margarine"), fad-diet books ("Bread is the root of all evil"), the nightly news ("Milk saves the world!"), and that beacon of frequently off-the-wall information, the Internet. "People are extremely confused about what to eat," acknowledges New York-based physician Jana Klauer, M.D., author of "How the Rich Get Thin". She and other prominent nutrition experts helped us set the record straight, exposing seven myths you might have heard -- but shouldn't believe.

Related: 35 Pantry Staples for Healthy Eating

Myth: A calorie is a calorie.

In fact, our bodies can distinguish one type of calorie from another. "We handle fat calories, carb calories, and protein calories differently," says Andrew Weil, M.D., author of "Eating Well for Optimal Health." "Some tend to be stored as fat; some tend to be digested more quickly." Knowing the distinction (and, moreover, eating accordingly) can help ease blood-sugar woes and protect your health.

Take simple carbohydrates such as sugar, white bread, and white rice, for example. The body breaks down and quickly absorbs these foods; this process causes a spike in insulin. Over time, this pattern can cause insulin resistance in some people. Complex carbohydrates and protein, however, "take longer to digest and don't cause that spike in blood sugar, so insulin is released in a more desirable, gradual manner," explains Klauer. And while taking in fewer calories than you expend is still the way to lose weight, it's important to choose the right foods. "I see people counting calories and eating junk," Klauer says. "If those calories aren't from nutritious food, they may be thin, but they won't feel or look their best." Weil's perfect mix? Forty to 50 percent of calories from good carbohydrates (beans, winter squashes, whole grains, berries), 30 percent from good fats (olive oil, nuts, avocados), and 20 to 30 percent from healthy proteins (fish, soy, reduced-fat dairy products).

Myth: The less fat I eat, the better.

"There are still people who believe that fat intake should be kept as low as possible, Weil says. "What's more important are the kinds of fats you eat." Good fats like omega-3 fatty acids, which the body can't produce on its own, help with brain function and children's development, and they may stave off heart disease and arthritis.

In the kitchen, use extra-virgin olive oil for dressings and low-heat dishes and grapeseed or expeller-pressed, organic canola oil for high-heat cooking. "A lot of refined vegetable oils (corn, safflower) are high in omega-6s, which are pro-inflammatory," says Weil, adding that low-level inflammation may contribute to disease.

Packaged foods are a major source of unhealthy oils, so read ingredient lists carefully. "Avoid soy oil," he warns. "It may be one of the major pro-inflammatory fats in the American diet." And when it comes to anything generic like "vegetable oil," Weil says, there's no telling what's inside, so it's best to steer clear. How do you make the transition from a bad-fat diet to a good-fat diet? "Minimize your consumption of meat and full-fat dairy products, fast food, and products made with coconut and palm-kernel oil, partially hydrogenated oils, vegetable shortening, and common vegetable oils," Weil says. "Eat more wild salmon, flaxseed, olive oil, nuts, and avocados."

Myth: If it says "organic," it must be nutritious.

When the label appears on a packaged food, buyer beware. Many manufacturers capitalize on the word to sell nutritionally deficient products, say experts. "Organic junk food is still junk food," explains Marion Nestle, Ph.D., M.P.H., professor of nutrition at New York University and author of "What to Eat." Take organic Oreo-like cookies. "They sound healthier, but with all the sugar and oil, they are just a disguised version of the same thing," says Klauer -- albeit minus the pesticides. So how can you avoid the organic trap? First, read labels. And use common sense. "Ask yourself before you eat something, 'What benefit does it have to my body?' If you can't come up with anything, don't eat it."

Myth: Whole-grain products are always beneficial.

When you buy products labeled "whole grain," says Nestle, you may assume you're getting a healthy dose of fiber, which helps keep your digestive system running smoothly and reduces your risk of numerous diseases. But like "organic," terms like "whole grain" can be misleading on packaged foods; always check the fiber content, says Nestle.

Weil encourages people to go for actual grains -- wild rice, quinoa, barley, and brown rice -- over flour-based foods as often as possible because grains tend to have a lower glycemic load (GL), a measure of how quickly carbohydrates turn into sugar in your body. "When you pulverize starch into flour, it has a huge surface area for enzymes to react on and turns quickly into sugar," he says. High GL foods cause blood sugar to spike and insulin secretion to surge, says Weil; over time this pattern may lead to insulin resistance, obesity, and other health problems.

This doesn't render bread off-limits. But pay close attention to texture; if you see big pieces of grain, says Weil, that's a good sign that it has a lower GL. As for pasta, he recommends Japanese soba and Italian whole wheat and stresses the importance of cooking all pasta al dente.

Related: 25 New Ways to Eat Avocados

Myth: If a label says "zero trans fats," then it contains no trans fats.

In this case, the ingredient list reveals more than the nutrition label. "A product can say zero trans fats and still have a small percentage," says Weil.

How so? The Food and Drug Administration allows for up to half a gram of trans fat under the "zero" label. The Institute of Medicine, however, maintains that there's no safe minimum level of trans fat. Look for ingredients such as shortening or partially hydrogenated oil to tip you off that the food has some trans fat.

Myth: If some soy is good, all-soy-all-the-time is better.

We hear a lot about the benefits of soy, but as with most things, moderation is key. "You can eat too much soy," Weil says. Moreover, he explains, the type of soy you eat matters greatly.

"It's desirable to eat moderate regular portions of whole-soy foods like edamame, soy milk, tofu, and tempeh," -- traditional foods whose health benefits have been shown in Asian population studies, says Weil. But when it comes to highly refined soy products, such as fractionated soy foods, soy protein isolate, or added soy isoflavones -- found in certain protein powders and energy bars -- there's no comparable evidence for health benefits, he explains. Soy isoflavones, in fact, may carry risks associated with thyroid dysfunction, so Weil advises staying away from them.

Myth: Healthy food always costs more.

"The manufacturers of junk foods would love for you to think that," says Nestle. But if you look closely (and shop wisely) you'll see that some of the healthiest foods don't cost much.

In general, the less packaging, the less you'll pay. A pound of granola from a health-food-store bulk aisle in Virginia, for example, is $1.79 a pound, while a pound of packaged granola at a nearby supermarket costs $5.79.

In the produce aisle, keep in mind that eating seasonally and locally can help your bottom line; midwinter blueberries in Boston, for instance, cost up to $4.99 a pint, but local summer berries are about half that price. Bargains also abound at farmers' markets due to reduced transport costs and the fact that there's no middle man.

Some processed foods, of course, are downright cheap. But consider why, says Weil. "Many are made with government-subsidized ingredients like corn oil and high-fructose corn syrup." Even if they're inexpensive on the shelf, he emphasizes, they're no bargain health-wise.

Three Times Mom Was Right
An apple a day...
Studies have shown that the polyphenols in apples may protect brain from neurodegenerative diseases such as Alzheimer's by helping to prevent oxidative damage. (Apple juice has been shown to have a healthy dose of polyphenols, too, but the highest concentration is in the skin.)

Breakfast is the most important meal of the day.
A healthy breakfast is essential for weight maintenance and mental energy, says Klauer. "But don't spike your insulin in the morning with sugary cereal, a bagel, or a Danish, because you'll just be tired and hungry later." Instead, opt for a breakfast that is rich in protein and complex carbohydrates.

You are what you eat.
Though often referred to as the body's fuel, food is really much more. "Digestion, absorption, and metabolism convert everything you eat into small molecules that are reassembled to construct your own body parts," Nestle says. "So you are made from molecules that were first assembled by the plants and animals you eat." Of course, your diet isn't the only determinant of health, notes Weil. "But it's something you potentially have control over."

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No myths here -- just healthy, delicious comfort food.