Flaxseed and other plant-based foods including walnuts, canola oil, and
soybeans are rich in an omega-3 fatty acid called ALA.
But flaxseed lacks the omega-3 fatty acids EPA and DHA, which have shown
cardiovascular benefits in past studies. EPA and DHA are found in fatty fish
such as salmon and mackerel, fish oil supplements, and some
Does ALA deliver the same benefits as EPA and DHA? The jury's still out on
that, note the researchers, who included James Friel, PhD, of Canada's
University of Manitoba. The optimal dose of ALA is also not known.
Flaxseed and Firefighters
Friel's team studied 62 male firefighters in the Canadian city of
Why firefighters? The researchers explain that firefighters tend to have
risk factors for coronary heart disease, including high stress levels, high-fat diets, little exercise while in the fire hall,
and being older than 40.
The researchers gave the firefighters flaxseed oil supplements in various
doses, fish oil supplements, or a placebo to take daily for 12 weeks.
As expected, blood levels of EPA and DHA rose in the fish oil group, and ALA
rose in the flaxseed oil group. EPA levels also rose in the flaxseed oil group,
but only at the higher doses (2.4 to 3.6 grams per day). The researchers write
that it's "quite attainable" to get that much ALA from foods without
Since flaxseed oil doesn't contain EPA, the firefighters' bodies must have
converted some of the ALA into EPA. That didn't seem to happen at the lower
doses of flaxseed oil.
DHA was a different story. The flaxseed oil group didn't get any increase in
DHA levels; DHA only rose in the fish oil group.
None of the groups gained any advantage in terms of lowering total or LDL
("bad") cholesterol, raising HDL
("good") cholesterol, or reducing blood levels of inflammatory
chemicals. The experiment was too short to track long-term health benefits.
The study was funded, in part, by the Canadian Flax Council and Flax