An egg is an egg — or is it?

Sen. Blanche Lincoln, D-Ark., right, picks up a basket of chicken eggs as Heifer International President and CEO Jo Luck looks on Monday, Dec. 16, 2002. A flock of chicks will be given in the names of her 99 Senate colleagues to needy families in some of 47 countries around the world this holiday season. (AP Photo/Danny Johnston)Danny Johnston / AP

Most people think of eggs as being about the same — some are bigger than others but generally they all have the same stuff inside of them. But now, eggs are becoming available in different varieties, including some packed with heart-healthy, omega-3 fatty acids. But do the benefits outweigh the extra cholesterol? Nutrition Notes columnist Karen Collins offers answers to these and other reader questions.

Q: Is it true that some eggs have the same healthy type of fat in salmon?
Yes. The type of fat chickens are fed affects the type of fat in their eggs. Several brands of eggs are available from hens given a diet that includes ground flaxseed, a source of omega-3 fat. Compared to a traditional egg that has essentially no omega-3 fat, these eggs may have about 0.4 grams of omega-3 fat each. That amount is similar to the omega-3 content of a three-ounce portion of fish moderate in omega-3 fat. A two-egg serving would contain as much omega-3 fat as a portion of fish high on the omega-3 scale, like rainbow trout, sea bass and sockeye salmon. (Other types of salmon contain even more omega-3 fat.)

Although the saturated fat in two eggs would only be a little more than in a serving of fish, there is one point you should consider. People sensitive to cholesterol may be concerned about the 370 milligrams of cholesterol in two eggs since that amount exceeds the recommendation for a whole day.

Q: Are egg white omelets healthier than regular omelets?If an omelet made from four to six egg whites was prepared in the same way as one made with two to three whole eggs, the egg white omelet would contain 80 to 120 fewer calories. An egg white omelet is also significantly lower in fat and cholesterol than one made with whole eggs. But be aware that some so-called "egg white omelets" are actually made with a mixture of whole eggs and egg whites.

Furthermore, although whole eggs are commonly considered bad for your health, the cholesterol-raising saturated fat content of whole eggs is not particularly high. Egg yolks are high in cholesterol, but studies show that saturated fat is a much greater risk for many people than cholesterol in food. A whole egg omelet does provide more iron than an egg white one.

Whichever form of omelet you choose, for a healthful version, limit any added cheese or use a reduced-fat kind. The total number of calories in any omelet depends on how much oil is added to the pan and whether cheese is added. By including plenty of vegetables, like onions, mushrooms, peppers, and spinach, you'll have the best nutritional balance.

Q: Are brown eggs more nutritious than white eggs?A: The breed of hen determines the color of the eggshell. White hens lay white eggs and dark hens lay brown eggs. Shell color has nothing to do with egg quality, flavor, nutritional value or cooking characteristics.