Fish oil capsules may be as beneficial as oily fish

By Lorraine L. Janeczko

NEW YORK (Reuters Health) - Fish oil capsules may have the same health benefits as oily fish, according to new research from Serbia.

Omega-3 (n-3) fatty acids from fish oil and from oily fish both modulate platelet lipid profiles efficiently, the authors wrote online January 6 in Nutrition Research.

Either oily fish or fish oil capsules taken at recommended levels increased eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in both red blood cells (RBCs) and platelets in healthy volunteers who didn't eat a lot of fish, they wrote.

"These findings suggest that public-aimed dietary recommendations for long-chain n-3 polyunsaturated fatty acids (LC n-3-PUFAs) had moderate cardioprotection, according to the analysis of selected cardiovascular risk markers," wrote lead author Ivana Djuricic, of the University of Belgrade in Serbia, by email to Reuters Health.

"Eating oily fish and taking fish oil supplements in recommended doses had only moderate cardioprotection after eight weeks, but six months or more should provide better results," she added.

To compare the relative effectiveness of oily fish with fish oil supplement in changing EPA and DHA levels in RBCs and platelets, Ms. Djuricic and her colleagues conducted a randomized, crossover trial in healthy middle-aged volunteers who did not eat more than one fish meal per week.

They enrolled 33 volunteers between 44 and 64 years of age who were not taking any regular medications or dietary supplements containing omega-3 fatty acids, calcium, or vitamin D. Their body mass index (BMI) was <30 kg/m and their blood pressure was <140/90 mmHg.

Two participants dropped out for reasons unrelated to the study.

The researchers randomly assigned participants to one of two groups. During the first eight weeks, the salmon group ate 150 g cold smoked skinned fillet of Norwegian Atlantic farmed salmon twice per week, while the fish oil capsule group took a commercial fish oil capsule with meals.

The salmon provided 274 mg EPA + 671 mg DHA per day, while the commercial fish oil supplement provided 396 mg EPA + 250 mg DHA per day.

After a six-month washout period, the participants switched groups and repeated the study for the second eight weeks. Over the course of the study, both groups received the same total doses of EPA and DHA.

All participants made four visits to the clinic, one before and one after each eight-week period, to have their blood samples collected and their RBCs and platelets analyzed for fatty acids.

In the end, both the salmon and fish oil capsule groups had significant increases in the EPA and DHA content in their RBCs and platelets. The increase in EPA in both RBCs and platelets was higher with capsules, and the increase in DHA in both RBCs and platelets was higher with salmon. The overall incorporation of EPA and DHA into RBCs and platelets did not differ (p>0.05).

The sum of EPA + DHA content in platelets increased 38% in the salmon group and 31% in the fish oil capsule group.

In a secondary analysis, the researchers found that the average EPA + DHA content in RBCs was 6.7%. While this was lower than the 8% they considered to be cardioprotective, they suggested that 8% might be reached after a longer intervention or a higher dietary intake of LC n-3 PUFAs.

They say their study used the highest-quality fish and fish oil capsules, and that other fish species and supplements with lower EPA and DHA content and bioavailability may yield lower results.

"The authors have clearly demonstrated that there doesn't appear to be much difference between eating fish or consuming fish oil as a means to increase your bodily EPA and DHA content. Both routes of administration work equally well," wrote Dr. Mark K. Larson, of the Biology Department of Augustana College in Sioux Falls, South Dakota, in an email to Reuters Health.

"EPA and DHA are the same no matter how they are consumed, and it would be highly unlikely that the body would process and metabolize these fatty acids any differently from fish or from fish oil," he said.

As to whether these findings should affect the advice doctors give their patients, Dr. Larson commented, "Possibly. It might be that more EPA and DHA are required to achieve the levels associated with cardioprotection."

"However," he added, "it's worth noting that the study looked at averages of the whole group, rather than individuals. Our research group and others have found that there is substantial variability from person to person in how they incorporate EPA and DHA from their diet. It's possible that not all individuals can reach the cardioprotective level, regardless of how much they ingest."

SOURCE: http://bit.ly/1mLaaCu

Nut Res 2014.

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