Sink or swim: fish oil
supplements and human
In 1970, two Danish researchers heard what sounded like a fish tale: Despite consuming a
high-fat diet consisting mainly of seal and whale meat and blubber, the Inuit people of northern
Greenland had a remarkably low rate of coronary artery disease (CAD) and almost nonexistent
diabetes mellitus. Highly carnivorous, the traditional Inuit diet supplies about 280 grams of
animal protein and 135 grams of fat per day, with few or no vegetables (Bang, H. O., et al.,
Lancet, 1971)—in other words, exactly the opposite of what most nutritionists recommend.
Intrigued by these reports, Hans Olaf Bang and Jørn Dyerberg mounted
an expedition to the northwest coast of Greenland, traveling across an ice
sheet by dog sled to reach a remote village of approximately 1,350 Inuit.
The researchers collected and analyzed blood samples from 61 male and
69 female Inuit and compared their plasma lipid profiles to those of healthy
Danes. Their finding: The Inuit had lower levels of several types of lipids,
including total cholesterol and plasma triglycerides, than Danish controls
(Bang, H. O., et al., Lancet, 1971). Bang and Dyerberg later discovered that the
Inuit had higher-than-normal amounts of two omega- 3 fatty acids—
docosahexaenoic acid (DHA, C22:6n- 3) and eicosapentaenoic acid (EPA, C20:sn- 3)—in
their plasma and platelet lipids that increased blood clotting time, leading
the researchers to hypothesize that omega-3s could protect the Inuit from
the cardiovascular consequences of their high-fat diet (Dyerberg, J., and
Bang, H. O., Lancet, 1979).
Bang and Dyerberg’s hypothesis spawned an entire industry that sought
to encapsulate the protective components of the Inuit diet in a convenient pill
that would obviate the need to consume seal or whale blubber or even fish,
which many people find unpalatable. Omega-3s were hailed as the panacea
for all of Western society’s ills, from cardiovascular disease to cancer to cognitive decline. Although early clinical trials seemed to reinforce the cardioprotective effects of omega-3s, more recent trials have produced mixed results,
at best. Some researchers have even suggested that a high intake of omega-3s
could be harmful to certain populations.
A 2014 report questioned the entire premise behind Bang and Dyerberg’s work, claiming that the Danish researchers vastly underestimated the
prevalence of CAD in the Inuit (Fodor, J. G., et al., http://dx.doi.org/10.1016/j.
cjca.2014.04.007). According to the study, not only did Inuit in the 1970s have
rates of CAD similar to or greater than non-Inuit populations, they also had
excessive mortality from stroke and an overall mortality rate twice as high
as that of non-Inuit. “Considering the dismal health status of Eskimos [Inuit],
it is remarkable that instead of labeling their diet as dangerous to health, a
hypothesis has been construed that dietary intake of marine fats prevents
CAD and reduces atherosclerotic burden,” the researchers write.
• the omega- 3 fatty acids DHA and
EpA have physiological effects that
may improve cardiovascular and
• clinical trials of fish oil supplements
containing DHA and EpA have
produced mixed results.
• Researchers are still divided on
whether omega- 3 fatty acid
supplements are beneficial, neutral,
or even harmful to human health.