A daily DHA dose of 540 mg, equivalent to two servings of fish per week, was associated with significant increases in the Omega-3 Index (EPA + DHA) from about 5.3% at the start of the study to over 7.5% after eight weeks. In contrast, the O3I for the control group did not change significantly.
“This current study demonstrated that a low supplemental intake of fish oil results in an increased O3I which is reflective of the preferential incorporation of DHA into myocardial membranes,” wrote researchers from the University of Wollongong in the Journal of the American College of Nutrition.
“In young and healthy adults who were free from CVD, resting HR [heart rate] was slowed, yet no appreciable modification of HRV [heart rate variability] responsiveness was evident in either the resting bradycardia or during cardiovascular reflex challenges (parasympathetic or sympathetic dominant) meaning that there was no change to the homeostatic process requiring rapid HR perturbations.
“This provides some support for the direct influence of long-chain ω-3 PUFA [omega-3 polyunsaturated fatty acids] on cardiac intrinsic beat rate independent of the autonomic nervous system in this group of healthy adults.”
Cardiovascular health
The study adds to a large body of evidence supporting the potential cardiovascular benefits of omega-3s, first reported by Dr Jorn Dyerberg, Hans Olaf Bang, and Aase Brøndum Nielsen in landmark papers on the topic in the The Lancet in 1971 The American Journal of Clinical Nutrition in 1975.