Omega-3 fatty acids and risk of cardiovascular disease in Inuit: First prospective cohort study

No prospective study have ever assessed if marine n-3 polyunsaturated fatty acids protect Inuit against cardiovascular disease as claimed. It is highly relevant as cardiovascular disease (CVD) incidence rates are rising concurrent with a westernization of diet. We aimed to assess the association between blood cell membrane phospholipid content of eicosapentaenoic acid and docosahexaenoic acid (EPA + DHA) on CVD risk in Inuit.

We used data from a cohort of adult Greenlanders with follow-up in national registers. The main outcome was fatal and non-fatal CVD incidence among participants without previous CVD. The continuous effect of EPA + DHA was calculated as incidence rate ratios (IRRs) using Poisson regression with age as time scale, adjusting for age, sex, genetic admixture, lifestyle and dietary risk factors.

Out of 3095 eligible participants, 2924 were included. During a median follow-up of 9.7 years, 216 had their first CVD event (8.3 events/1000 person years). No association between EPA + DHA and CVD risk was seen, with IRR = 0.99 per percentage point EPA + DHA increase (95% CI: 0.95-1.03, p = 0.59). No association was seen with risk of ischemic heart disease (IHD) (IRR = 1.03, 95% CI: 0.97-1.09) and stroke (IRR = 0.98, 95% CI: 0.93-1.03) as separate outcomes or for intake of EPA and DHA.

We can exclude that the CVD risk reduction is larger than 21% for individuals at the 75% EPA + DHA percentile compared to the 25% percentile. We need a larger sample size and/or longer follow-up to detect smaller effects and associations with IHD and/or stroke.