The skinny on healthful fats

Health claims on food are proliferating, and one that's particularly popular is using omega-3 fatty acids to improve cardiovascular health, in addition to other health benefits.

Here's the lowdown on this healthy fat.

Q: What are omega-3s, and is there a difference between the omega-3s in fish and those in walnuts?

A: Omega-3 fatty acids are a type of polyunsaturated fat. There are a few types of omega-3s: EPA (eicosapentaenoic acid), DHA (docosahexaenoic acid) and ALA (alpha linolenic acid).

"They are not the same thing — we have to stop talking about omega-3s and talk about DHA and EPA and ALA as separate fatty acids," says Debra Palmer Keenan, Ph.D., a nutrition professor at Rutgers University in New Jersey. EPA and DHA are the most valuable to health and wellness. They come from fish oils. Both play an important role in normal function of the heart, brain, eyes, nervous system, kidney and liver. These "essential" fats also have been proved to reduce the risk of cardiovascular disease and inflammation.

"If you get ALA from walnuts, flaxseed or canola oil, it can be beneficial because it gets converted to DHA and EPA, but that's only if ALA is already lacking in your diet, which it probably isn't," says Jay Whelan, a professor of nutrition and omega-3 researcher at the University of Tennessee.

Eating more ALA just for it to be converted to EPA and DHA is not recommended. "The amounts converted are very small, and in the long run, ALA starts to replace the needed DHA in the tissues — not a good thing," adds Whelan.

Q: Why are omega-3s getting so much attention?

A: One of the key health benefits is that they significantly reduce the risk for sudden death caused by cardiac arrhythmias and decrease all-cause mortality in patients with known coronary heart disease.

In fact, last year the FDA allowed the following claim to be placed on certain foods: "Supportive but not conclusive research shows that consumption of EPA and DHA omega-3 fatty acids may reduce the risk of coronary heart disease. One serving of [name of food] provides [x] grams of EPA and DHA omega-3 fatty acids." The label must state the quantity of omega-3 fatty acids the product contains; however, the FDA did not require the food to contain a minimum amount of omega-3s to carry the claim.

A: "This could be one of those nutrients that becomes a 'magic bullet,' but we don't say things are conclusive until there have been many more studies — yes, the evidence looks strong, but we are not quite there yet," says Keenan.

Omega-3s (specifically DHA and EPA) are being examined for other health benefits, including treating rheumatoid arthritis, ulcerative colitis and Crohn's (because of their anti-inflammatory properties); treating depression and other psychological disorders (because they may boost levels of serotonin and dopamine, decreasing depression and violent behavior); reducing the risk of diabetes, insulin resistance in people with diabetes, psoriasis and other skin conditions; helping osteoporosis (because they may enhance bone density); and fighting cancer (they may inhibit cancer cells in the breast, prostate and colon). In infants, omega-3s may improve cognition and visual acuity.

Q: What are some other sources of omega-3s?

A: Soybeans and soybean oil, canola oil, walnuts and flaxseeds and their oils are rich sources of ALA.

Fatty fish, such as salmon and tuna, and fish oil are rich sources of EPA and DHA. For a complete list of omega-3s and where to find them, check out www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=hstat1a.table.38454

The FDA advises not to eat shark, swordfish, king mackerel or tilefish because of mercury. Albacore ("white") tuna, another commonly eaten fish, has more mercury than canned light tuna. Review mercury levels at www.cfsan.fda.gov/~frf/sea-mehg.html.

Q: Can you get omega-3s without eating fish?

A: There are new products on the market made with encapsulated fish oil (e.g., Arnold Smart & Healthy Omega-3 bread), so it doesn't smell or taste like fish. If you're not getting omega-3s from any other fish sources, these are a good option, but we don't know enough to say that the fish doesn't have other properties working in conjunction with the omega-3s to create these purported health benefits.

Q: What about omega-3 supplements?

A: Some research has shown positive outcomes for omega-3 fish supplements over a placebo. Plus, "So far, fish-oil supplements have lacked contaminants such as mercury and PCBs," says Dr. Tod Cooperman, ConsumerLab.com's president.

For information on fish-oil supplements, see: www.consumerlab.com/results/omega3.asp; and for omega-3 seed oils, visit www.consumerlab.com/results/flaxseed.asp.

Q: How much do I need to reap the benefits?

A: The American Heart Association's (AHA) recommendations:

• If you don't have documented Coronary Heart Disease (CHD), eat at least two servings of fatty fish per week, along with other foods rich in omega-3s.

• With CHD, eat at least one daily meal that includes a fatty fish, or take a daily fish-oil supplement (0.9 gram per day of EPA).

• The AHA suggests consulting your physician before taking any supplement.

Charles Stuart Platkin is a nutrition and public health advocate, author of the best seller "Breaking the Pattern" (Plume, 2005) and founder of Integrated Wellness Solutions. Copyright 2005 by Charles Stuart Platkin.