The primary benefits of fish oil are due to the essential fatty acids the supplements provide. Much research has been conducted about DHA and EPA. Some of the latest research focuses on a lesser known omega-3 called DPA.

Docosapentaenoic acid or DPA is one of the long-chained omega-3 fatty acids found in a few species of cold water fish and ocean mammals. It has been theorized that the presence of DPA contributed to the overall cardiovascular health seen in native Inuit populations. They ate a lot of seal. The fatty meat is rich in DPA.

More common species contain little if any DPA. For example, most of the supplements manufactured in the US (even the prescription supplement) are derived from the menhaden. Not a coldwater species, it is not a source of DPA.

DPA is not the longest of the long-chained fatty acids. That would be DHA or Docosahexaenoic acid. DHA is now recognized as being essential for normal brain development in infants. It is present in human breast milk, but not cow's milk or soy. It is believed that the absence of DHA may explain why breast-fed children typically score higher on IQ tests than formula-fed children.

Some fish oil supplements provide mostly the shorter-chained omega-3 called EPA or Eicosapentaenoic acid. The omega-3s found in flax and most other vegan sources are the shortest of the long-chained fatty acids. They are called ALA (alpha-linolenic acid).

The human body has the ability to produce the longer chained omega-3s from the shorter chained ones, although the process is generally described as inefficient. The closer the omega-3 is to DHA, the easier it can be converted. DPA is the closest to DHA. All of the longer chained omega-3s can be converted into the shorter ones if the body needs them. That process is simpler and much more efficient.

The best fish oil supplements contain a large amount of DHA, a reasonable amount of EPA and a small amount of DPA. You do not have to choose seal oil to get DPA.

Researchers recently confirmed that the presence of DPA increased the triglyceride lowering benefits and provided greater improvement in good HDL cholesterol levels. This study seems to confirm the theory about why the Inuit populations had such healthy hearts.

A coldwater species called hoki seems to provide the ideal amount of each of the important omega-3s. You might get some of the benefits of fish oil from menhaden, but hoki is the best choice. Look for the species name on the label.