Four capsules (about 1tsp) of flax oil, containing a total of 2.4g of alphalinolenic acid (ALA) and taken daily for as little as two weeks, are sufficient to produce a significant increase in the ALA and eicosapentaenoic acid (EPA) content of red blood cell (RBC) phospholipids. These findings were published at the University of Manitoba in Winnipeg, Canada, and the University of North Dakota in Grand Forks. The researchers worked with a cohort of firefighters and paramedics living in the Winnipeg area. Firefighters were studied because their high-stress jobs and typical high-fat diets place them at increased risk of cardiovascular disease (CVD). Sixty-two adults, nearly all men, were recruited and assigned randomly to one of six treatment groups: 1.2g (2 capsules) of flax oil; 2.4g (4 capsules) of flax oil; 3.6g (6 capsules) of flax oil; 0.6g (1 capsule) of fish oil; 1.2g (2 capsules) of fish oil; or placebo (2 capsules of sunflower oil). Subjects were instructed to take the assigned number of capsules daily for 12 weeks.

In general, the ALA content of RBC phospholipids increased significantly in the 2.4g and 3.6g flax oil/day, but not in the fish oil groups. The ALA content of RBC phospholipids increased 1.7-fold and 2-fold from baseline in the 2.4g and 3.6g flax oil groups, respectively. The EPA content of RBC phospholipids increased significantly in groups taking 2.4g and 3.6g of flax oil daily and in both fish oil groups. The DPA content increased in the 2.4 g flax oil group and in both fish oil groups, but not in the 3.6 g flax oil group. The DHA content increased only in the fish oil groups.

Overall, the lowest dose of flax oil (1.2g/day) did not change the fatty acid composition of RBC phospholipids, whereas the 2.4g had a greater total omega-3 concentration, mainly due to elevated levels of ALA, EPA and DPA. Fish oil consumption increased the EPA, DPA and DHA concentrations of RBC phospholipids. The researchers concluded that an intake of 2.4g (about 1tsp) of flax oil, added to the daily diet, is sufficient to achieve important changes in the fatty acid content of RBC phospholipids. The suggested amount is easily obtained by regularly consuming oil seeds like flax, nuts and green, leafy vegetables. Flax Council of Canada, www.flaxcouncil.ca/

From the April 13, 2009, Prepared Foods E-dition