Q. Do all eggs contain omega-3 fatty acids, or only the eggs labeled as such? What gives eggs a high omega-3 content?

A. In this case, the chicken came before the egg. Egg producers now feed their hens special diets to produce eggs with enhanced amounts of the omega-3 fatty acids alpha-linolenic acid (ALA) and docosahexaenoic acid (DHA). Flaxseed is loaded with ALA, so eggs produced by flaxseed-fed hens have a higher ALA content. An Eggland's Best egg, for example, has 100 mg of the omega-3s ALA and DHA.That's three times the amount in an ordinary egg. Other egg manufacturers, such as Gold Circle Farms, feed their hens a diet rich in DHA (found primarily in fatty fish and fish oil) from cold-water algae. Each of their eggs has approximately 150 mg of DHA, versus 18 mg in an ordinary egg.

Should you opt for omega-3-enhanced eggs? It certainly wouldn't hurt: The American diet is typically low in these polyunsaturated oils, which are important to cardiovascular and nervous system health. Keep in mind, however, that these eggs provide only a modest boost of omega-3s and probably shouldn't be your only source. Most adults would benefit from 1 to 2 grams of omega-3s per day, preferably in the form of fish (a 3-ounce serving of salmon provides approximately 1.7 grams).

This Ask the Expert was written by Heather Jones, a registered dietitian, freelance writer, and nutrition professional based in Washington, D.C.