Men with elevated levels of triglycerides in their blood (hypertriglyceridaemia) had lower levels of markers in their blood, such as C-reactive protein (CRP), and interleukin-6 (IL-6), following daily supplements of a DHA oil, compared to men receiving olive oil.
“The anti-inflammatory effects of docosahexaenoic acid (DHA) in hypertriglyceridemic men have not been previously reported, to our knowledge, and were the focus of this study,” explained lead author Darshan Kelley from the USDA’s Agricultural Research Service.
Hypertriglyceridaemia has been linked to an increased risk of hardening of the arteries (atherosclerosis), a major risk factor for cardiovascular disease (CVD) - the causes almost 50 per cent of deaths in Europe, and is reported to cost the EU economy about €169bn ($202bn) per year.
The results of the new study, published in this month's Journal of Nutrition, reflect well for algae-derived DHA marketers, such as the manufacturer of the LifesDHA brand used in the trials, Martek Biosciences.
Omega-3 fatty acids, most notably DHA and EPA (eicosapentaenoic acid), have been linked to a wide-range of health benefits, including reduced risk of cardiovascular disease (CVD) and certain cancers, good development of a baby during pregnancy, joint health, and improved behaviour and mood.
Kelley, in collaboration with scientists from the University of California, Davis, and the Veterans Affairs Northern California Health Care System, recruited 34 men with hyperrtriglyceridaemia (age range 39 to 66) and randomly assigned them to receive with DHA supplements (3 grams per day) or olive oil placebo for 90 days.
The double-blind, randomized, placebo-controlled parallel study showed that supplementation with DHA for 45 days resulted in decreased levels of the number of circulating white blood cells (neutrophils) by 11.7 per cent, and these reductions were maintained until the end of the 90-day study (10.5 per cent reduction).
The number of circulating neutrophils was positively linked to the concentration of omega-6 fatty acids in red blood cells, and negatively linked to levels of both EPA and DHA in the red blood cells.
While no other markers of inflammation changed during the first 45 days, at the end of the study Kelley and her co-workers report that levels of C-reactive protein (CRP) had decreased by 15 per cent, and IL-6 had decreased by 23 per cent.
Furthermore, levels of the anti-inflammatory matrix metalloproteinase-2 rose by 7 per cent, they said.
“In conclusion, DHA may lessen the inflammatory response by altering blood lipids and their fatty acid composition,” wrote Kelley and her co-workers.
The results build on earlier data from the same study (American Journal of Clinical Nutrition, August 2007, Vol. 86, pp. 324-333), which reported that the DHA supplementation was associated with decreased fasting levels of triacylglycerol (24 per cent), very low density lipoproteins (92 per cent), and intermediate-density lipoproteins (53 per cent).
Source: Journal of Nutrition 2009, Volume 139, Pages 495-501, doi:10.3945/jn.108.100354"DHA Supplementation Decreases Serum C-Reactive Protein and Other Markers of Inflammation in Hypertriglyceridemic Men” Authors: Darshan S. Kelley, D. Siegel, D.M. Fedor, Y. Adkins, B.E. Mackey