12 March 2010

You've likely heard this advice: eat fatty fish twice a week. Fatty fish like salmon and trout are particularly high in omega 3 fats. These fats seem to do many good things for our bodies. But you may also have heard that there are dangerous levels of mercury and PCB's in some fish.

Here's what Omega 3's may do for you:

Research is most supportive of omega 3's in the area of heart health.

Best Picks for Omega 3 Fatty Acids:

• Canola oil
• Flaxseeds
• Walnuts
• Salmon
• Herring
• Trout
• Sardines
• Pacific Oysters
  

The omega 3's in fish seem to have a bigger health benefit than those from plant sources, which is why the American Heart Association recommends eating two servings  of fish a week. "EPA" and "DHA" are the specific omega 3's in fish.

One of the problems with eating more fish is contamination with toxic chemicals. The two toxins of greatest concern are PCB's (polychlorinated biphenyls) and mercury. But if you plan which fish to eat carefully, you should be able to avoid dangerous levels of PCB's and mercury.

One of the safest fish to eat is wild Alaskan salmon - either fresh or canned. Check out the Environmental Defense Fund's recommendations for which fish is safe to eat and how often:    http://www.edf.org/page.cfm?tagID=17694

But what if you don't like fish? You can take supplements, but you need to be careful not to overdose.

Should You Supplement?

If you eat fatty fish regularly and do not have heart disease, I don't recommend taking omega 3 pills. Healthy people without heart disease who do not eat fish regularly, can take up to 1000 mg (1g) of EPA/DHA a day safely. But this is where it gets tricky. That's 1 gram of EPA and DHA - not 1 gram of fish oil a day. Most of the labels on fish oil supplements simply say "1000 mg fish oil". That's not 1000 mg of DHA + EPA.  You have to read the label very carefully to find out how many pills equal 1000 mg of DHA + EPA. For most brands of supplements, it will be three pills.

Just like fish, fish oil supplements can be contaminated with toxins - particularly PCB's. Most supplement makers do a good job of purifying their products and getting those toxins out. However, not all are safe. Check out the fish oil supplements that are safe at the Environmental Defense Fund's website: http://www.edf.org/page.cfm?tagID=16536

If you have heart disease, you may need more DHA and EPA to get heart health benefits. But talk to your doctor before you take high doses. DHA and EPA act as blood thinners and can cause bleeding in high doses. High doses of fish oil can also increase blood sugar.

Do not take fish oil pills without talking to your doctor first if you are taking:

Blood Thinning Medicines These include:

• Aspirin
• warfarin (Coumadin)
• clopedigrel (Plavix).

Diabetes Medicines These include:

• Insulin
• glipizide (Glucatrol)
• glyburide (Micronase or Diabeta)
• glucophage (Metformin).

 
Beth Kitchin MS RD
Assistant Professor
UAB Department of Nutrition Sciences

Abbreviations: EPA = eicosoapentaenoic acid
DHA = docosahexaenoic acid
mg = milligrams
g = grams