Should men eat fatty fish once a week?

Yes, according to researchers who studied rates of heart failure among older Swedish men.

But not because the data support that conclusion.

First, the details.

• Diet in 39,367 middle aged and older Swedish men was measured using food-frequency questionnaires.
• Hazard ratios were calculated.
  • A hazard ratio is the difference between 2 survival curves, representing the reduction in the risk of death in a group getting treatment vs. a control group.

And, the results.

• Men who ate fatty fish (herring, mackerel, salmon, whitefish, and char) once a week were 12% less likely to develop heart failure compared to men who never ate fatty fish.
  • However, this association did not reach statistical significance.
• Eating more fatty fish did not give a greater benefit.
  • In fact, the risk of heart failure was the same as in men who never ate fatty fish or fish oils.
• Men who consumed 0.36 grams a day of fatty acids had a significant 33% reduced risk of heart failure.
  • But men who consumed more (0.46 or 0.71 grams per day) had the same risk as men who are none or very little.

The bottom line?
The authors concluded, “Moderate intake of fatty fish and marine omega-3 fatty acids is associated with lower rates of heart failure in men, but… the men did not gain a greater benefit by eating more of these foods.”

I think the researchers had difficulty deviating from the conventional wisdom that fatty fish is good for you.

Actually, none of the men benefited by eating fatty fish, according to the results. It was only the intake of omega-3 that was important in achieving cardiovascular benefit.

The authors explain that the reason the benefits of eating fatty fish failed to achieved statistical significance, while  omega-3 did, was a consequence of the break points for the 5 levels of fish intake that were decided on before the study started. Different groupings might have resulted in statistical significant findings.

Based on the evidence from 189 other studies, there remains modest evidence of an association between reduced risk of heart disease and increased consumption of fish and omega-3 fatty acids.

4/23/09 17:30 JR