Diet of canadian indigenous people is traditionally composed with large amount of fish, which are rich in omega-3 polyunsaturated fatty acids (n3-PUFAs), essentially EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). High levels of those n3-PUFAs in membrane phospholipids have been associated with decreased coronary heart disease (CHD) risk, and some studies have found a positive effect on HDL and triacylglycerol, but their effects on LDL- or total-CHOL are not consistent. Recent data suggest that apolipoproteins ApoA1 and ApoB may improve CHD risk assessment by identifying more high-risk individuals than the usual lipid profile alone. Our objective was to assess the association of n3-PUFA relative concentrations in RBC with apolipoproteins ApoA1 and ApoB100 in the Cree population from the James Bay Territories.
Our study population consisted of 790 subjects ≥18y who participated in the Multi-community Environment and Health longitudinal study in Iiyiyiu Aschii conducted among the Cree population in seven communities of James Bay from 2005 to 2009. Clinical questionnaires and examinations have been completed. Fatty acid composition of RBC membrane phospholipids and plasma lipid levels were measured in blood samples. Analysis of covariance was used to compare n3-PUFA mean relative concentrations between groups, and multiple regression analyses were performed to assess the association of n3-PUFA concentrations with CVD risk factor levels adjusting for potential confounders.
The mean relative concentration of combined EPA+DHA and n3-PUFA accounted for 4.1 and 6.3% of total fatty acids, respectively, and differed significantly according to the age and the community (P < 0.0001). Coastal residents showed higher relative concentrations of EPA, DHA and DPA and a lower n-6:n-3 ratio than inland residents, but the difference was not significant. In contrary, trans fat was significantly higher among inland residents (P < 0.0001). EPA+DHA was not associated with Apo-B or Apo-A1 levels, but higher concentrations of total n3-PUFAs were positively associated with higher levels of Apo-A1 (β = 0.0412, P = 0.0002), and lower concentrations of Apo-B (β = −0.0505, P = <0.0001) levels. The n-6:n-3 ratio was significantly associated with Apo-B100 (β = 0.2792, P = 0.0002) and inversely associated with Apo-A1 (β = −0.2494, P = 0.0003) levels.
Our results showed that n3-PUFA may have a positive influence on non-HDL-C risk factors responsible of CHD. Since high levels of Apo-B are related to heart disease, diet is a significant factor that should not be ignored. Sustained efforts should also be done to maintain traditional diet based on fish and games, which primarily provides the Cree population with n3-PUFAs and their cardioprotective effects.
© 2011 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.