Carole Blanchet

Impact of Waist Circumference on the Relationship Between Blood Pressure and Insulin: The Quebec Health Survey

Hyperinsulinemia has been suggested to be involved in the etiology of obesity-associated hypertension. The objective of the present study was to quantify, in a population-based study, the respective contributions of excess adiposity (body mass index [BMI]), waist circumference (WC), fasting insulin levels, and insulin sensitivity to the variation of resting blood pressure. The Quebec Health Survey was used to obtain fasting plasma insulin and glucose levels and resting blood pressure as well as anthropometric measurements in a representative sample of 907 men and 937 women. When the sample was divided into tertiles of BMI and further stratified on the basis of the 50th percentile of WC (88 cm in men), nonobese men in the first BMI tertile (<23.2 kg/m2) but with abdominal obesity were characterized by an increased systolic blood pressure (SBP) compared with nonobese men with low WC (130±18 versus 120±11 mm Hg; mean±SD; P=0.075). The SBP was comparable to SBP values measured among men in the top BMI tertile (129±14 mm Hg for BMI ≥26.6 kg/m2). When subjects were classified into tertiles of fasting insulin and WC, no association between insulin levels and blood pressure was noted, once the variation in WC was considered. Insulin sensitivity (estimated with homeostasis model assessment [HOMA]) did not explain variation in blood pressure in men, whereas the contribution of HOMA in women was of marginal clinical significance (R2 of <1.3%; P<0.0001). These results suggest that the documented association between obesity, fasting insulin, insulin sensitivity, and blood pressure is largely explained by concomitant variation in WC.

Fatty acid composition of wild and farmed Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss).

The goal of this study was to examine the FA composition of wild and farmed Atlantic salmon (AS) and rainbow trout (RT). FA profiles were obtained by GC/FID. Results showed that lipid and n−3 highly unsaturated FA contents of farmed and wild AS were similar. Total n−3 and n−6 PUFA were significantly higher in farmed AS than in wild AS. Farmed RT contained more fat and less n−3 PUFA than wild RT. Our results show that farmed salmonids provide high levels of n−3 HUFA to consumers.

Fish Consumption and Blood Lipids in Three Ethnic Groups of Québec (Canada)

The purpose of this study was to compare fish intake and plasma phospholipid concentrations of n−3 fatty acids, in particular of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), among representative population samples of Québecers, James Bay Cree, and Inuit of Nunavik (Canada). The relationships between these concentrations and cardiovascular disease (CVD) risk factors were also investigated and compared in the three populations. In 1990–1992, the study subjects had participated in the extensive Santé Québec health surveys conducted in southern Québec, James Bay, and Nunavik. Significant differences in levels of CVD risk factors were found among these three populations. Globally, Inuit showed the lowest risk status for CVD compared with Cree and Québecers, despite the high prevalence of cigarette smoking and obesity. Daily fish intakes varied significantly among the three groups, averaging 13, 60, and 131 g for Québecers, Cree, and Inuit, respectively. Concentrations of EPA+DHA in plasma phospholipids were highest among Inuit (8.0%), second-highest among Cree (3.9%), and lowest among Québecers (1.8%). When the three populations were grouped together, there was a positive association between concentrations of EPA+DHA stratified into quartiles and HDL cholesterol, with a significant relation in quartile 4 (EPA+DHA ≥4.04%). An inverse relation was also found betwen EPA+DHA and triacylglycerols in quartile 4. Our results indicate that increased consumption of fish as a source of n−3 fatty acids is beneficially associated with levels of HDL cholesterol and triacylglycerols.

Blood pressure among the Inuit (Eskimo) populations in the Arctic.

Aims: Studies of blood pressure among various Inuit (Eskimo) populations in the Arctic have given inconsistent results. Most studies reported lower blood pressure among the Inuit as compared with the predominantly white national populations. This has been attributed to traditional subsistence practices and lifestyle. This study compared the blood pressure among the major Inuit population groups with other populations and examined the associations with factors like age, gender, obesity and smoking. Methods: The study comprised four Inuit populations from Alaska, Canada, and Greenland with participation rates ranging from 51% to 73%. In a cross-sectional design, 2,509 randomly selected adults from 31 villages were examined. Blood pressure, anthropometric measurements, smoking, and medication were recorded. Results: Mean systolic blood pressures ranged from 116 to 124 mm Hg among men and 110 to 118 among women in the four populations. Mean diastolic blood pressures ranged from 75 to 78 mm Hg among men and from 71 to 73 among women. Systolic blood pressure increased with age. Male gender, obesity, being a non-smoker, and being on anti-hypertensive treatment were associated with high systolic and diastolic blood pressure. Adjusted for age, body mass index, smoking, and anti-hypertensive treatment, blood pressure differed among the populations (p≤0.001). Mean systolic blood pressure was low among the Inuit compared with most European populations of the INTERSALT study, but higher than in several Asian populations and the Amazonian Indians. Conclusions: Inuit blood pressures rank intermediate on a global scale but low in comparison with most European populations. The Inuit population is not homogeneous, and this is reflected in blood pressure differences among the four regional subgroups. The role of the traditional diet, a rural lifestyle with a low level of psychosocial stress, and genetics must be further explored.

Plasma omega-3 and psychological distress among Nunavik Inuit (Canada).

Marine omega-3 (n-3) fatty acid eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids have been associated with beneficial effects in mental health. Cultural and social changes have been related to a decline in mental health of the Inuit, but the role of diet has received scant attention. We examined the relationship between psychological distress (PD) and plasma n-3 among 368 Nunavik Inuit aged 18-74 years who took part in a survey in 1992. Participants were categorized as high-level PD if they scored over the 80th percentile of the PD Index Santé-Québec Survey (PDISQS-14), and non-distressed subjects were those who scored less than this cutoff. Compared with the non-distressed group, n-3 concentrations in the PD group were significantly lower in women but not in men. Compared with the lowest tertile of EPA + DHA, the odds ratios for high-level PD among women were 0.32 (95% CI: 0.13-0.82) for the second, and 0.30 (95% CI: 0.10-0.90) for the third tertile, after controlling for confounders. In males, there were no significant associations between EPA+DHA and PDISQS-14 scores. Our findings suggest that marine n-3 may play a role in PD among Inuit women. The gender difference observed in our analysis must be examined more carefully in future studies.

Is marine mammal fat or fish intake most strongly associated with omega-3 blood levels among the Nunavik Inuit?

Here we determined the relationship between red blood cell (RBC) omega-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFAs) and usual dietary marine food product intake among 630 Nunavik Inuit adults. Marine food product intake was determined by a food frequency questionnaire (FFQ) and fatty acids were quantified in RBC membranes. Multiple linear regression was undertaken to determine the relationship between marine food product intake and RBC n-3 LC-PUFAs (dependent variable). Mean RBC n-3 LC-PUFA level was 9.16 ± 0.11% [SEM]. The highest correlations noted with RBC n-3 LC-PUFAs were for marine mammal fat (r(s)=0.41, P<0.0001) and fish (r(s)=0.35, P<0.0001). Age, total marine mammal fat and fish intakes were the variables that contributed the most to predicted RBC n-3 LC-PUFAs and explained 34%, 15% and 5%, respectively, of its variances. Our study indicates that marine mammal fat intake is more important than fish in accounting for RBC n-3 LC-PUFA levels among the Nunavik Inuit.

Plasma n-3 fatty acids and psychological distress in aboriginal Cree Indians (Canada)

OBJECTIVE To examine the relationship between psychological distress (PD) and plasma n-3 long-chain (LC) PUFA, i.e. EPA, docosapentaenoic acid (DPAn-3) and DHA. DESIGN Population-based, cross-sectional Santé-Québec Health Survey (1991). Participants were categorized as high-level PD if they scored over the 80th percentile of the PD Index in the Santé-Québec Survey; non-distressed subjects were those who scored less than this cut-off. Associations between tertiles of n-3 fatty acids (FA) and the risk of high-level PD were expressed as odds ratios, with the lowest tertile as the reference group. SETTING Québec, Canada. SUBJECTS Data were analysed from a representative sample of 852 James Bay Cree Indian adults aged 18 years and over. RESULTS Proportions of n-3 FA were statistically significantly lower in the PD than in the non-distressed group. After adjustment for confounders, EPA was the only individual n-3 FA significantly associated with the risk of high-level PD. Combinations of EPA + DHA or EPA + DPAn-3 + DHA or the sum of n-3 were also associated with the risk of high-level PD. Compared with the lowest tertile of EPA + DHA, the OR for high-level PD was 0.89 (95 % CI 0.59, 1.36) for the second and 0.56 (95 % CI 0.32, 0.98) for the third tertile, after controlling for confounders. CONCLUSIONS In the present retrospective, cross-sectional study, we found that proportions of n-3 LC PUFA in plasma phospholipids, markers of n-3 LC PUFA consumption from fish, were inversely associated with PD.