Associations between omega-3 fatty acids and 25(OH)D and psychological distress among Inuit in Canada

Figures & data

Table 1. Characteristics associated with serious psychological distress (SPD): International Polar Year Inuit Health Survey (n = 1699).

	n	% SPD	p-value*
Sex			<0.001
Male	659	7.7
Female	1.040	13.4
Mean age (years)			<0.001
<50	1.217	13.2
≥50	482	6.0
Marital status			0.002
Married/common law	602	9.4
Not married	1.091	14.5
Days out on the land:			−0.096
0–5, mean: 1.7	460	14.4
6–27, mean: 13.4	464	9.1
27–365, mean: 75.8	481	6.9
Feeling of being alone			<0.001
Yes	852	16.9
No	820	5.1
Smoking			<0.001
Yes	1160	13.6
No	534	6.0
Income			<0.001
<$20,000	776	15.6
>$20,000	783	6.4
BMI (kg m^–^2)
<30	1.066	13.4	<0.001
≥30	605	8.10
Education			−0.077
≤Elementary	404	12.8
Secondary	556	14.7
≥Secondary	711	7.6

*P-values for chi-square test for difference or Kendall’s tau.

Table 2. Mean (SD) biomarker levels by age group for participants who answered the Kessler 6 psychological distress assessment: International Polar Year Inuit Health Survey (N = 1,649).

		Total n-3*	EPA + DHA*	N-3 LC-PUFAs*	25(OH)D nmol/L
Age (years)	n	Mean (SD)	Mean (SD)	Mean (SD)	Mean (SD)
18–49	1173	4.91(2.62)	3.31(2.03)	4.62(2.58)	48.5(28.0)
≥ 50	476	8.01(4.12)	6.14(3.40)	7.77(4.10)	84.8(33.5)
Total	1649	5.80(3.43)	4.13(2.81)	5.52(3.40)	58.9(33.9)

*Fatty acids expressed as % of total RBC membrane fatty acid content.

Table 3. Variables by tertile for n-3 LC-PUFAs and 25(OH)D and test for trend.

	N-3 LC-PUFAs*				25(OH)D
Tertile	1	2	3	p-value†	1	2	3	p-value†
Age (years)	36.6(13.8)	38.4(13.0)	52.2(13.9)	<0.001	32.5(10.2)	41.3(13.9)	53.1(13.7)	<0.001
% female	63.0	60.6	60.1	0.225	64.3	60.0	59.8	0.045
% married/common law	58.7	64.4	69.7	<0.001	61.8	65.9	64.9	0.114
Days out on land (SD)	25.4(43.7)	30.4(47.5)	37.4(53.9)	0.000	21.4(37.4)	33.1(48.7)	37.9(56.2)	<0.001
% feeling being alone	54.0	50.1	47.3	0.055	55.2	51.1	46.3	0.009
% smoking	77.9	73.2	58.2	<0.001	82.6	69.3	57.4	<0.001
% highest income	44.0	44.9	52.0	0.077	39.2	51.2	51.7	<0.001
K6 score (SD)	6.5(5.3)	6.1(4.8)	4.9(4.5)	<0.001	6.8(5.1)	5.9(4.9)	4.9(4.6)	<0.001

*EPA+DHA+DPA n-3

^† Test for trend over tertiles.

Table 4. ORs for SPD by selected fatty acids and 25(OH)D with high values as reference, age specified and all observations.

	<50		≥50		All observations
	Unadjusted	Adjusted*	Unadjusted	Adjusted*	Unadjusted	Adjusted*
	n = 1173	n = 901	n = 476	n = 343	n = 1649	n = 1244
	OR (95% CI)	OR (95% CI)	OR (95% CI)	OR (95% CI)	OR (95% CI)	OR (95% CI)
Total n-3 FAs
High	1.00	1.00	1.00	1.00	1.00	1.00
Medium	1.13 (0.73–1.73)	0.97 (0.57–1.79)	4.24 (1.17–15.35)	10.15 (1.22–83.69)	1.52 (1.00–2.31)	1.00 (0.58–1.76)
Low	1.31 (0.86–1.99)	1.34 (0.81–2.45)	5.01 (1.42–17.95)	13.43 (1.64–109.82)	2.11 (1.42–3.15)	1.58 (0.92–2.68)
p-trend^†	0.202	0.210	0.012	0.008	<0.001	0.057
N-3 LC-PUFAs
High	1.00	1.00	1.00	1.00	1.00	1.00
Medium	1.08 (0.65–1.54)	1.02 (0.55–1.75)	4.59 (1.18–15.45)	10.11 (1.22–83.47)	1.44 (0.94–2.19)	0.95 (0.54–1.68)
Low	1.21 (0.85–1.93)	1.26 (0.84–2.55)	5.51 (1.42–17.96)	12.82 (1.60–104.30)	2.21 (1.49–3.28)	1.67 (0.98–2.84)
P-trend^†	0.237	0.155	0.012	0.010	<0.001	0.027
EPA+DHA
High	1.00	1.00	1.00	1.00	1.00	1.00
Medium	1.11 (0.81–1.90)	1.11 (0.61–1.88)	3.86 (1.06–14.12)	4.37 (0.87–21.92)	1.66 (1.10–2.51)	1.13 (0.65–1.97)
Low	1.23 (0.85–1.98)	1.34 (0.73–2.28)	5.55 (1.55–19.23)	6.01 (1.26–29.29)	2.06 (1.38–3.09)	1.53 (0.88–2.66)
P-trend^†	0.237	0.366	0.006	0.022	<0.001	0.104
EPA
High	1.00	1.00	1.00	1.00	1.00	1.00
Medium	1.05 (0.68–1.62)	1.26 (0.70–2.24)	1.79 (0.51–6.22)	1.66 (0.38–7.34)	1.62 (1.08–2.43)	1.09 (0.64–1.86)
Low	1.31 (0.87–1.98)	1.64 (0.94–2.88)	4.98 (1.65–15.08)	4.17 (1.10–15.84)	1.78 (1.20–2.65)	1.32 (0.77–2.26)
P-trend^†	0.197	0.080	0.002	0.021	0.005	0.287
DHA
High	1.00	1.00	1.00	1.00	1.00	1.00
Medium	1.18 (0.80–1.89)	1.24 (0.72–2.23)	1.36 (0.46–3.99)	1.28 (0.35–4.37)	1.91 (1.25–2.93)	1.44 (0.82–2.53)
Low	1.32 (0.87–2.03)	1.31 (0.73–2.30)	2.71 (1.01–7.08)	2.58 (0.77–7.69)	2.43 (1.61–3.67)	1.86 (1.07–3.23)
P-trend^†	0.184	0.396	0.037	0.111	<0.001	0.026
25(OH)D
High	1.00	1.00	1.00	1.00	1.00	1.00
Medium	1.40 (0.91–2.17)	1.49 (0.85–2.61)	2.11 (0.70–6.32)	2.42 (0.68–8.59)	1.61 (1.05–2.46)	1.31 (0.75–2.29)
Low	1.66 (1.08–2.54)	1.60 (0.89–2.89)	3.03 (1.07–8.64)	1.94 (0.54–6.95)	2.59 (1.73–3.86)	1.96 (1.10–3.49)
P-trend^†	0.020	0.118	0.035	0.378	<0.001	0.017

*Adjusted for gender, age, marital status, days spent out on the land, feeling of being alone, income and smoking.

^† Test for trend over tertiles.