Milk and eggs have earned their place in the American diet because they're good sources of calcium and protein, respectively. These days, some brands are also being touted as a good source of another nutrient: omega-3s.
Omega-3 fatty acids are in demand because of their proven beneficial effects on heart health. The Institute of Medicine, which advises the government on health issues, recommends 1,100 milligrams of omega-3s per day for women and 1,600 mg for men.
Two types of omega-3s — docosahexanoic acid (DHA) and eicosapentaenoic acid ( EPA) — have been shown in rigorous, large-scale studies to slow the buildup of plaque in the arteries, lower triglycerides in the blood, and reduce the risk of irregular heartbeat and of cardiac events in people who have already suffered a heart attack.
A third type of omega-3, alpha-linolenic acid (ALA), may be beneficial for heart health too, though it hasn't been studied as extensively. Found in canola and soybean oils, ALA is already abundant in the American diet. In the body, about 5% of it gets converted into DHA and EPA.
In order to be useful, omega-3s must be consumed in fairly large doses that can be difficult — and expensive — to get through fortified foods such as eggs and milk, says Dr. Donald Hensrud, chief of the division of preventive medicine at the Mayo Clinic in Rochester, Minn.
Omega-3 eggs were developed in 1990 by a Canadian food scientist who was looking for a way to reverse declining consumption of eggs, which had gone out of favor due to their high cholesterol content. Producing an egg enriched with omega-3s turned out to be easy: All he had to do was feed hens flaxseed or another natural source of the fats and they ended up in the eggs.
Flaxseed contains ALA, so that ends up being the predominant omega-3 in fortified eggs. Few egg cartons reveal as much, however.
Land O Lakes Omega-3 All-Natural Eggs claim to contain 350 milligrams of omega-3s per egg, but the types and amounts of omega-3 aren't specified on the carton. Ditto for Organic Valley Omega-3 Extra Large Eggs, which boast 225 mg of the fats — types not specified — per egg.
Smart Balance, by contrast, reveals that its Omega-3 Grade A Natural Large Eggs each contain 160 mg of ALA and 32 mg of DHA.
That information is important, since ALA, DHA and EPA may differ greatly in their effects on cardiovascular health, says Dr. Freny Mody, director of cardiology for the Greater Los Angeles Veterans Affairs Health Care System.
In eggs, levels of the two omega-3s known to be useful — DHA and EPA — are generally lower than levels of ALA, which is found in affordable chicken feeds like flax and canola. Feeding hens fishmeal and algae, two good sources of DHA and EPA, is a pricier proposition.
Working omega-3s into milk is considerably more difficult, but food scientists have figured out how to suspend DHA and EPA in milk by encapsulating the fats in a gel, says Joy Dubost, a Washington, D.C., nutritionist and member of the Institute of Food Technologists. (The suspension technology also keeps the milk from tasting like fish, the source of the omega-3s, according to Organic Valley's website.)
Omega-3-fortified milks may provide the "right" type of omega-3s, but amounts vary from one brand to another, and between fat and skim varieties, Hensrud says.
Smart Balance Fat Free and Low Fat Milk and Omega-3s, for instance, contain a combined 32 mg of EPA and DHA per serving. Organic Valley Omega-3 Whole Milk, meanwhile, provides 50 mg of EPA and DHA, plus 50 mg of ALA.
Consumers should note that all these amounts in fortified foods pale in comparison with the quantities found naturally in fatty fish, says Susan Bowerman, assistant director of the ULCA Center for Human Nutrition. Three ounces of wild Alaska salmon provide 1,000 to 1,500 mgs of EPA and DHA combined; the same goes for 3 ounces of sardines.
That means it's a lot easier to meet one's daily requirement by eating fish than by drinking enriched milk. One would have to gulp down five glasses of Organic Valley Omega-3 Whole Milk, for example, to consume 500 milligrams of omega-3s.
And the number of eggs it would take to meet that minimum is even greater, Bowerman says. It would take a dozen Smart Balance Omega-3 Grade A Natural Large Eggs to provide 500 mg of EPA and DHA.
All those eggs and glasses of milk come with a significant amount of saturated fat and cholesterol, Hensrud says. Fortified milk poses a particular challenge: Because omega-3s are more easily soluble in fat, enriched whole milk usually contains more omega-3s than the skim or low-fat versions.
"So you're starting out with products that may not be the best for heart health to begin with," he says. "I'd approach them with a bit of skepticism."