Island-specific differences in exposure to chronic disease risk factors
Study participants were drawn equally from Waiben, the main commercial and administrative center of the Torres Strait Islands (n = 50), and Mer, a smaller, more remote, island (n = 50). There were no island differences in participant gender (males: n = 27 in Waiben, n = 24 in Mer, p=0.548) or in the prevalence of current smokers (smokers: n = 17 in Waiben, n = 16 in Mer, p=0.832). Residents of Mer largely consumed a diet that is traditional in the Torres Strait Islands (Niccoli and Partridge, 2012), including frequent consumption of fresh seafood. In comparison, Waiben residents had a more ‘westernized’ diet, characterized by significantly higher consumption of takeaway food and alcohol, and lower consumption of seafood (Table 1). Although current dogma suggests such dietary habits would be associated with increased chronic disease risk, increased levels of chronic disease risk markers were not observed for Waiben residents. Specifically, Mer residents had significantly (p<0.05) greater systolic blood pressure, mean arterial pressure (MAP), C-reactive protein, IL-12, IL-18, and IFNγ, compared to Waiben residents. While not achieving statistical significance (p=0.100), the prevalence of T2D in Mer residents was also greater than in Waiben residents (48% versus 30%, respectively; Table 1).
Table 1.  Characteristics of Waiben and Mer residents.
Characteristic  Waiben (n = 50)  Mer (n = 50)  Unadjusted P-value *  Age-adjusted P-value †
Age [years]  40 (31, 54)  58 (36, 65)   0.003  NA
Exposure chronic disease risk factors
Sugar-sweetened beverage consumption [serves/day]  1 (0, 1)  1 (0, 1)  0.576  0.562
Fruit consumption [serves/day]  2 (1, 3)  2 (1, 2)  0.680  0.682
Vegetable consumption [serves/day]  3.5 (2.0, 5.0)  3.5 (2.0, 4.0)  0.609  0.606
Takeaway consumption [serves/week]  1 (0, 2)  0 (0, 1)   0.011   0.009
Seafood consumption [serves/week]  2 (1, 3)  2 (1, 5)   0.020   0.021
Alcoholic beverage consumption [serves/day]  0.33 (0.00, 0.99)  0.20 (0.00, 1.88)  0.597  0.592
Smoking [cigarettes/day]  0.00 (0.00, 5.25)  0.00 (0.00, 2.25)  0.804  0.800
Physical activity [min/week]  180 (90, 236)  210 (150, 360)  0.925  0.925
Biological chronic disease risk factors
Glucose [mmol/L] ‡  5.2 (4.7, 5.7)  5.6 (4.8, 6.5)  0.056   0.050
HbA1c [mmol/mol] ‡  38 (34, 42)  43 (36.5, 45)  0.127  0.109
Systolic blood pressure [mmHg]  121 (112.5, 129.5)  129 (115.3, 139.5)   0.028   0.025
Mean arterial pressure [mmHg]  87.8 (72.0–113.7)  95.8 (61.0–126.3)   0.034   0.033
Body mass index [kg/m2]  31.1 (25.8, 37.9)  32.1 (25.5, 36.5)  0.893  0.893
Waist circumference [cm]  105 (92, 116)  116 (101, 125)  0.019   0.016
Waist to hip ratio  0.62 (0.53, 0.69)  0.68 (0.61, 0.75)  0.035   0.027
Inflammatory biomarkers ‡
Interferon γ [pg/mL]  0.69 (0.61, 0.83)  0.96 (0.67, 1.18)   <0.001   <0.001
C-Reactive protein [mg/L]  0.36 (0.23, 0.51)  1.36 (0.63, 1.76)   <0.001   <0.001
Interleukin-1β [pg/mL]  0.39 (0.19, 0.61)  0.37 (0.23, 0.5)  0.534  0.536
Interleukin-12p40 [pg/mL]  1.98 (1.26, 3.47)  6.32 (3.31, 11.37)   <0.001   <0.001
Interleukin-12p70 [pg/mL]  0.46 (0.41, 0.51)  0.82 (0.62, 1.07)   <0.001   <0.001
Interleukin-13 [pg/mL]  1.72 (1.48, 1.94)  1.82 (1.82, 2.07)   0.008   0.008
Interleukin-15 [pg/mL]  7.37 (4.36, 10.7)  8.76 (6.89, 12.23)  0.281  0.272
Interleukin-18 [pg/mL]  11.34 (4.57, 18.17)  21.38 (13.26, 37.51)   <0.001   <0.001
Interleukin-4 [pg/mL]  4.97 (4.61, 6.09)  6.80 (5.95, 9.23)   <0.001   <0.001
MCP-1/CCL2 [pg/mL]  52.77 (32.89, 88.41)  111.60 (67.65, 149.9)   <0.001   <0.001
Tumor necrosis factor α [pg/mL]  0.17 (0.11, 0.30)  0.47 (0.40, 0.68)   <0.001   <0.001
Species-alpha diversity
Count [Chao1 species richness]  68.5 (64.0, 72.3)  68.0 (57.8, 73.3)  0.805  0.805
Distribution [Shannon evenness index]  0.68 (0.61, 0.71)  0.71 (0.66, 0.75)   0.027   0.026
Variety [Shannon diversity index]  2.83 (2.50, 2.98)  2.94 (2.73, 3.20)  0.061  0.060
Results are median (Q1, Q3). * ANOVA between Mer and Waiben. † ANCOVA between Mer and Waiben adjusted for age. ‡ analysis performed on log-transformed data. Abbreviations: MCP: Monocyte Chemoattractant Protein; MIP: Macrophage Inflammatory Protein. The explanation for such a proatherogenic biomarker profile in Mer residents was not immediately apparent. Mer residents were significantly older than Waiben residents (mean age [years]: 41.5 versus 51.7; p=0.003), a recognized risk factor for chronic disease (Arumugam et al., 2011). However, significant differences in measures of blood pressure and inflammatory markers remained even after adjusting for age (Table 1).