Gretchen Vannice

Dyerberg J, et al. Bioavailability of marine n-3 fatty acid formulations. Prostaglandins, Leukotrienes and Essential Fatty Acids, 2010; 83 (3):137-141.

In this study, they gave 3.3 grams of EPA and DHA to 72 people for 2 weeks, from 6 different sources/forms (one was corn oil placebo).  Serum levels of EPA and DHA increased in all 5 forms of fish oil used (non-concentrate/regular fish oil; cod liver oil; free fatty acid; ethyl ester concentrate; or re-esterified TG concentrate).

The results from taking regular fish oil and cod liver oil were similar; both had similar blood level increases. How they reported the results was instead of comparing the results to placebo, they took the position of comparing the other forms to regular fish oil and cod liver oil, “as if” regular fish oil and cod liver oil were “the standard” by which to compare the others.  With this approach, the re-esterified TG concentrate form improved blood levels better than regular fish oil and cod liver oil, and the result of consuming the EE concentrate on blood levels was less than regular fish oil and cod liver oil.

Issues with this study include: 2 weeks is a short time frame; levels in serum fluctuate and are not as meaningful a measure for physiological benefit (red blood cell membrane is better). They also did not know if the subjects consumed the supplements with food or not; consuming fish oil capsules with a fat-containing meal is known to improve absorption.

Neubronner, et al. Enhanced increase of omega-3 index in response to long-term n-3 fatty acid supplementation from triacylglycerides versus ethyl esters. Euro J Clin Nutrition, 2010;1-8.

In this study, 150 adults who had dyslipidemia and were on statin meds, volunteered to have their omega-3 blood levels tested 3 times (beginning, at 3 months, at 6 months). Subjects consumed 1.68 grams of EPA and DHA as either re-esterified TG fish oil concentrate or ethyl ester concentrate or a corn oil placebo (no EPA and DHA). They were instructed to consume the capsules with food.

At the end of 6 months, increases in EPA and DHA were significantly higher in both fish oil groups, yet blood levels of the re-esterified TG fish oil were higher, and it was significant compared to the ethyl ester group.

Six months is adequate to see real change in tissue levels. Compliance of subjects was measured and was good. The subjects, living in Germany, started the study with an average omega-3 red blood cell membrane level of 7%; this is higher than North American average. Even so, blood levels increased.

The response from clinicians has been “omega-3 tissue levels improve nicely with both forms. That is good news”.

Of interest, most of the fish oil used in clinical research, that used concentrated fish oil, has been completed using ethyl ester concentrate form.

It was also good to see a study where a naturally-derived product (fish oil) was to people taking a Rx drug. We know that taking fish oil has additive benefit for people on statin drugs, but that is another subject.