Omega-3 index – do you know yours?

January 29 2015

by Emily Ryan

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There is a large volume of research regarding the importance of long chain omega 3 fatty acid levels in our bodies, with reference to cardiovascular risk reduction as well as neurologic health and joint health. EPA and DHA are the specific long chain omega 3 fatty acids that are often at inadequate levels. The measurement of levels in your blood is a relatively inexpensive test that can help you to determine if your intake is adequate or not. Omnivores usually consume fish or fish oil, while vegans (and vegetarians) can supplement with EPA and DHA from marine algae. Here are a couple of recent studies:


Higher omega-3 index is associated with increased insulin sensitivity and more favourable metabolic profile in middle-aged overweight men.

Albert BB1, Derraik JG1, Brennan CM1, Biggs JB1, Smith GC2, Garg ML3, Cameron-Smith D1, Hofman PL4, Cutfield WS4.
Sci Rep. 2014 Oct 21;4:6697. doi: 10.1038/srep06697.


We assessed whether omega-3 index (red blood cell concentrations of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)) was associated with insulin sensitivity and other metabolic outcomes in 47 overweight men aged 46.5 ± 5.1 years. Participants were assessed twice, 16 weeks apart. Insulin sensitivity was assessed by the Matsuda method from an oral glucose tolerance test. Linear associations were examined; stratified analyses were carried out with participants separated according to the omega-3 index: lower tertiles (LOI; n = 31) and highest tertile (HOI; n = 16). Increasing omega-3 index was correlated with higher insulin sensitivity (r = 0.23; p = 0.025), higher disposition index (r = 0.20; p = 0.054), and lower CRP concentrations (r = -0.39; p < 0.0001). Insulin sensitivity was 43% higher in HOI than in LOI men (Matsuda index 6.83 vs 4.78; p = 0.009). Similarly, HOI men had disposition index that was 70% higher (p = 0.013) and fasting insulin concentrations 25% lower (p = 0.038). HOI men displayed lower nocturnal systolic blood pressure (-6.0 mmHg; p = 0.025) and greater systolic blood pressure dip (14.7 vs 10.8%; p = 0.039). Men in the HOI group also had lower concentrations of CRP (41% lower; p = 0.033) and free fatty acids (21% lower, p = 0.024). In conclusion, higher omega-3 index is associated with increased insulin sensitivity and a more favourable metabolic profile in middle-aged overweight men.

PMID: 25331725
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Intrinsic heart rate recovery after dynamic exercise is improved with an increased omega-3 index in healthy males

Macartney MJ1, Hingley L1, Brown MA1, Peoples GE1, McLennan PL2.
Br J Nutr. 2014 Dec;112(12):1984-92. doi: 10.1017/S0007114514003146. Epub 2014 Oct 30.


Dietary fish consumption contributes to a reduced risk of cardiac mortality. In the present study, the effect of low-dose fish oil (FO) supplementation on heart rate (HR) response to intense exercise and recovery was investigated in physically fit males. The subjects (n 26) were supplemented (double-blind, parallel design) with (2 × 1 g/d) soya bean oil (control) or tuna FO providing the long-chain n-3 PUFA DHA (560 mg) and EPA (140 mg). Erythrocyte omega-3 index (%EPA+DHA), HR, HR variability and HR recovery were analysed during rest, intense exercise and recovery at baseline and after 8 weeks of supplementation. The mean erythrocyte omega-3 index, which did not differ between the groups at baseline (control 4.2 (sem 0.2), n 13; FO 4.7 (sem 0.2), n 13), remained unchanged in the control group (3.9 (sem 0.2)), but increased in the FO group (6.3 (sem 0.3); P< 0.01). The mean HR during supine resting conditions (control 56 (sem 10); FO 59 (sem 9)) was not affected by FO supplementation. Poincaré analysis of HR variability at rest exhibited a decreasing trend in parasympathetic activity in the FO group (SD1 (standard deviation of points perpendicular to the axis of line of identity)/SD2 (standard deviation of points along the axis of line of identity): control 0.02 (sem 0.01); FO – 0.05 (sem 0.02); P= 0.18). Peak HR was not affected by supplementation. However, during submaximal exercise over 5 min, fewer total heart beats were recorded in the FO group (-22 (sem 6) ( = -4.5 beats/min)), but not in the control group (+1 (sem 4)) (P< 0.05). Supine HR recovery (half-time) after cycling was significantly faster after FO supplementation (control – 0.4 (sem 1.2) s; FO – 8.0 (sem 1.7) s; P< 0.05). A low intake of FO increased the omega-3 index and reduced the mean exercise HR and improved HR recovery without compromising the peak HR. A direct influence of DHA via reductions in the cardiac intrinsic beat rate was balanced by a reciprocal decrease in vagal tone.

PMID: 25355484