Fish linked to heart failure risk, omega-3 results mixed

For people conscious about their heart health, a new study suggests it may be best to eat fish instead of taking individual omega-3 fatty acids in supplement form.

After reviewing information on the habits and fatty-acid blood levels of more than 20,000 male doctors, researchers found mixed results when it came to omega-3 supplements and the men’s likelihood of heart failure, but eating fish regularly was linked to a lower risk.

According to the study’s senior researcher, the results are consistent with the American Heart Association’s (AHA) recommendations.

“Our findings showed a lower risk of heart failure in men consuming any amount of fish per week,” Dr. Luc Djoussé, a professor at Harvard Medical School in Boston said in an email. “Given current AHA recommendations, we do not believe that any change should be made based on our findings.”

The current recommendations are for people to eat two servings of fatty fish per week. Salmon, herring, sardines and albacore tuna are some of the fish considered the most beneficial, according to the AHA.

Some people, however, may prefer to take omega-3 fatty acid supplements that are available over the counter, but their benefits for heart health remain unclear.

One recent study, for instance, analyzed data from multiple past studies and found no link between omega-3 supplements and overall death rates (see Reuters Health story from September 11, 2012).

For the new study, published in the American Journal of Clinical Nutrition, Djoussé‘s group wanted to see if there was any connection between taking individual omega-3 fatty acids and one’s risk of heart failure.

They used information from the Physicians’ Health Study, an ongoing study of male doctors that began in 1982.

The researchers analyzed how much omega-3 fatty acid the doctors had in their bodies based on blood samples and food questionnaires, which also indicated how much fish the doctors ate.

They found that about 7 in 1,000 men who reported eating fish less than once per month suffered heart failure. That’s compared to about 4 in 1,000 men who reported eating more than one serving of fish per month.

Djoussé said that works out to be “about 30 percent lower risk of heart failure than that of men not consuming fish.”


As for the individual omega-3 fatty acids, things were a little more complicated.

Specifically, the researchers looked at eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and docosapentaenoic acid (DPA) in the men’s diets and bloodstreams.

Overall, the researchers did not see an effect for blood levels of EPA or DHA, which are the two fatty acids thought to be responsible for fish’s benefits and most often sold in the form of “fish oil” supplements.

There was a link between lowered heart failure risk and DPA, which is made in the body from EPA and can then be converted into DHA, according to Djoussé.

He told Reuters Health that their findings suggest DPA acts differently than the other fatty acids, but that needs to be confirmed by more research.

Also, while the researchers did see a link between eating fish and a lower heart failure risk, the study cannot prove whether or not the fish caused the lower risk.

Alice Lichtenstein, director of the Cardiovascular Nutrition Laboratory at Tufts University in Boston, told Reuters Health the study shows that the hope for a “quick fix” is fading.

“What we need to do - and I think this maybe reinforces it - is to put more effort on modifying the diet of people who are at an increased risk,” she said.

For example, eating fish may not be just beneficial thanks to the omega-3 fatty acids, but also because it displaces less healthy foods from a person’s diet.

Djoussé said until more studies are done, people should not change their diets as long as they’re already following the AHA’s guidelines.

SOURCE: American Journal of Clinical Nutrition, online September 5, 2012


Plasma and dietary omega-3 fatty acids, fish intake, and heart failure risk in the Physicians’ Health Study

The mean age was 58.7 y at blood collection. In a multivariable model, plasma α-linolenic acid (ALA) was associated with a lower risk of HF in a nonlinear fashion (P-quadratic trend = 0.02), and the lowest OR was observed in quintile 4 (0.66; 95% CI: 0.47, 0.94). Plasma EPA and DHA were not associated with HF, whereas plasma docosapentaenoic acid (DPA) showed a nonlinear inverse relation with HF for quintile 2 (OR: 0.55; 95% CI: 0.39, 0.79). Dietary marine n−3 FAs showed a trend toward a lower risk of HF in quintile 4 (HR: 0.81; 95% CI: 0.64, 1.02) and a nonlinear pattern across quintiles. Fish intake was associated with a lower risk of HF, with RRs of ∼0.70 for all categories of fish consumption greater than one serving per month.

: Our data are consistent with an inverse and nonlinear relation of plasma phospholipid ALA and DPA, but not EPA or DHA, with HF risk. Fish consumption greater than once per month was associated with a lower HF risk.
  Jemma B Wilk,
  Michael Y Tsai,
  Naomi Q Hanson,
  J Michael Gaziano, and
  Luc Djoussé

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