How much fish oil is enough?

This post just furthers this line of thinking out loud: How much fish oil is "enough"?

Observations over the last 30 years followed this path: If a little bit of omega-3 fatty acids from fish are beneficial in reducing cardiovascular events, and a moderate intake is even better, is even more better? When have we reached a plateau? When do adverse effects outweigh the benefits?

Some insight can be gained through studies that examined blood levels of omega-3s. Let's take a look at some data from 2002, a comparison of men dying from heart disease vs. controls in the Physicians' Health Study, Blood Levels of Long-Chain n–3 Fatty Acids and the Risk of Sudden Death.

This is a table that shows the blood levels of various fatty acids Group with sudden death vs Control Group:

Several observations jump out:

--The total omega-3 blood content differed significantly, 4.82 vs 5.24% ("Total long-chain n-3 polyunsaturated")
--Total omega-6 content did not differ
--Arachidonic acid (AA) content did not differ
--Linolenic acid content did not differ (i.e., plant sourced omega-3)

The fact that neither omega-6 nor arachidonic acid content differed counters the argument that Simopoulos has made that the omega-6 to omega-3 ratio (intake, not blood levels) is what counts. It also argues against the EPA to AA ratio (and similar manipulations) that some have argued is important. In this study, only the omega-3 level itself made a difference; no ratio was necessary to distinguish sudden death victims vs controls.

Further, quartiles of omega-3 blood levels showed graded reductions of risk:

An omega-3 blood level of 6.87% conferred greatest risk reduction. Depending on the model of statistical analysis, risk reductions of up to 81-90% were observed. Wow.

Taken at face value, this study would argue that:

--An omega-3 fatty acid blood level of 6.87% (or greater?) is ideal
--The omega-3 fatty acid blood level stands alone as a predictor without resorting to any further manipulation of numbers, such as relating EPA and/or DHA to AA levels.

Of course, this is just one study, though an important one. It is also not a study based on any intervention, just an observational effort. But it does add to our understanding.

We will develop these issues further in our upcoming Track Your Plaque Webinar on Wednesday, August 20th, 2008.

Comments (7) -

  • Anonymous

    8/9/2008 5:50:00 PM |

    I get the pharma grade fish oil pill called Lavasa.

    These are really expensive and can one buy similar good fish oil pills over the counter.  I take 4 per day?


  • Anonymous

    8/9/2008 6:34:00 PM |

    So to get a level of 6.8%, how many mg must you consume in a day?

  • AJL

    8/9/2008 7:05:00 PM |

    Great info!

    Is there a lab blood test (low cost) to have one's own DHA/EPA level tested to confirm the level is optimal?

  • M. Levin

    8/11/2008 2:39:00 PM |

    A couple of observations.

    One is that trans fats do not appear to be associated with sudden cardiac arrest. This does not say that they aren't associated with heart disease or that they are healthy.

    The other is that the Cordain et. al estimate of 21% of calories from fat (from primitive man) has been challenged by various sources as being too low based on observations of various recent primitive native cultures, especially based on observations that the parts of the animal that contained the most saturated fat were preferentially consumed. I've included a few references. Other can be found on the net. The point is that this is not established fact, but a guess or a scientific hypothesis.

    from Michael Eades Protein Power Blog  January 30, 2008

    ....Loren Cordain’s seminal paper ( on the plant/animal subsistence ratios of hunter/gatherers, ......
    ... Loren emailed me when I sent him this paper

    Nowhere in that paper do we give the numbers he quoted. We provided these ranges of macronutrient estimations are being most likely (protein 19-35% energy, carb 22-40% energy, and fat (28-58% energy).

    Other references

  • Tom

    8/11/2008 8:33:00 PM |

    Interesting topic. A couple of years ago a Dr. Leaf of Harvard Medical School made a statement that for those of us with angina fish oil could be deadly.
    I wonder if this idea has been disproven or is it still valid ?

  • Peter Silverman

    8/15/2008 3:02:00 PM |

    Scientists have shown that zero percent of cave men ate food from factories and feed lots.

  • buy jeans

    11/3/2010 8:46:40 PM |

    Of course, this is just one study, though an important one. It is also not a study based on any intervention, just an observational effort. But it does add to our understanding.