Medically Reviewed On: July 09, 2008

ANNOUNCER: Many people eat a healthy diet. They know the nutritional value of foods, they read food labels carefully and they follow dietary recommendations to the tee. Others are clueless. Which one are you? Test your nutrition knowledge by taking this short quiz.

Which contains more fat, margarine or butter?

BONNIE TAUB-DIX, MA, RD: Margarine and butter actually both have equal amounts of fat, so it's not as if one has less than the other. They could also be the same amount of calories. However, butter is more of a saturated fat than margarine is. If you're choosing margarines, be sure that you choose margarines that do not have trans fatty acids in them, because they act as saturated fats do, and they are not recommended for the prevention of heart disease.

ANNOUNCER: Which vegetables contain the most vitamins: fresh, canned or frozen?

BONNIE TAUB-DIX, MA, RD: Many people are under the misconception that canned or frozen vegetables have less vitamins and minerals than fresh and that sometimes is actually not true. Because, sometimes, when fresh vegetables are picked, let's say, in California and they're put on a truck and they have to travel across the country in the heat, in the cold, coming to New York, for example. Well, those vegetables could lose a lot of vitamins and minerals in transit. Whereas if they were picked in California and flash-frozen and then sent here on a frozen-food truck, then that vegetable could actually have more vitamins and minerals in it than fresh.

ANNOUNCER: Which foods pack a punch of iron?

BONNIE TAUB-DIX, MA, RD: To pack a punch of iron in your diet, you might want to eat enriched whole grain breads and cereals; spinach is high in iron. Believe it or not, prune juice is loaded with iron and also canned beans and dried fruits, such as dried apricots. What's important to also know about foods that are high in iron is that, when you eat them at the same time that you eat foods that are high in vitamin C-so, for example, if you're eating spinach, which is high in iron, and you have it with a grapefruit for dessert, that the vitamin C enhances the absorption of iron.

ANNOUNCER: You can get protein only from meat. True or false.

BONNIE TAUB-DIX, MA, RD: It's a misconception to think that protein only comes from meat. Poultry is a great source of protein, so is fish and egg and cheese and milk and also beans are also a very good source of protein, especially when you couple them with grains, such as rice and beans combined together. Peanut butter has protein, tofu has protein. Many soy products also have protein.

ANNOUNCER: Salads are a low calorie food. True or false.

BONNIE TAUB-DIX, MA, RD: I think that, when it comes to eating in restaurants, a lot of people think that, if they order a salad, that that's really going to be low in calories. And there are some salads, like a chef salad with a nice, thick blue cheese dressing could be a thousand calories as opposed to something like a-a meal that has chicken and, you know, meat that could even be lower in calories. So I think that, if you're ordering a salad, it's a good idea to ask for dressing on the side. And if you put a spoon of your favorite dressing on, even if it is high in fat, but just a spoon of it and put some balsamic vinegar over it, that's a good way to dilute down the flavor of something that you really like.

ANNOUNCER: A healthy diet should contain no fat. True or false.

BONNIE TAUB-DIX, MA, RD: There are many different sources of fat in the diet, and I think that fat has gotten a bad rap over the years. So fat is not necessarily the bad guy. A lot has to do with where the fat is coming from, whether it's a saturated fat, polyunsaturated, monounsaturated. For example, saturated fats, if you want to put it graphically, they're the fats that will stick to your arteries the fastest. They are usually fat that is solid at room temperature, like shortening and butter, the fat that's on meat. So those are the fats that are usually not recommended when you're trying to prevent heart disease and have a healthier diet. And the monounsaturated fats are in products like olive oil, canola oil, they're in olives, they're in avocado. So monounsaturated fats are usually recommended in terms of heart disease prevention.

ANNOUNCER: A bagel is equivalent to how many slices of bread: 2, 4, 6, 8?

BONNIE TAUB-DIX, MA, RD: One of the most popular foods, especially here, is a bagel. And one bagel is actually, if you put it on the scale and weighed it, a bagel could weigh 6 ounces. Well, that would be just like eating six pieces of bread, so most people don't realize that one bagel could be six pieces of bread. And if each piece of bread is 80 calories, you could do the math, that's a lot of calories to have and that's a plain bagel with nothing on it.

ANNOUNCER: The body can live without carbohydrates. True or false.

BONNIE TAUB-DIX, MA, RD: We need carbohydrates for energy, because they're the best source of energy that we have. We need carbohydrates for vitamins and minerals. We need carbohydrates for fiber, to help things moving along. So they're really important in the diet. Carbohydrates could be fattening if you're eating an excessive amount of carbohydrates. But if you eat the proper amount for your particular body, for your level of energy, then I think that, not only will you enjoy them, but you'll enjoy the benefits that they bring.

ANNOUNCER: Which foods contain a lot of vitamin C?

BONNIE TAUB-DIX, MA, RD: Foods that are high in vitamin C would be citrus fruits like oranges, grapefruits, orange juice, grapefruit juice. But, also, broccoli is high in vitamin C. Believe it or not, a baked potato is high in vitamin C. Cherries and strawberries are also high in vitamin C and so is cantaloupe.

ANNOUNCER: All fiber is alike. True or false.

BONNIE TAUB-DIX, MA, RD: There are many sources of fiber in the diet and there is soluble fiber and insoluble fiber. Soluble fiber would be foods like oats and apples and carrots, and these are foods that may actually help lower cholesterol levels. And insoluble fiber would be food like bran-type of products, and they actually help you to move your bowels more readily and help prevent constipation.

ANNOUNCER: If you are finding that your nutrition knowledge is not perfect don't fret, dietitians have some guiding principles that everyone can follow.

BONNIE TAUB-DIX, MA, RD: There's no one food or nutrient that's going to be magical. If you just try to think of a concert, if you went to hear just one instrument playing, it's nothing like hearing a whole, you know, a symphony. So there is a symphony of fruits and vegetables and vitamins and minerals and proteins and carbohydrates and fats out there. The key is trying to learn how to be a good conductor and put them all in your diet so that you know that you're meeting your needs, no matter what age you are.