Association Between Daily Dietary Eicosatetraenoic Acid Intake and the Lower Risk of Psoriasis in American Adults

Figures & data

Figure 1 Possible biosynthesis and metabolic pathway of long-chain n3 PUFA.

Figure 2 Flowchart of the screening process for the eligible participants selection from National Centre for Health Statistics (NHANES).

Table 1 Characteristics of Participants by Psoriasis

Variable	Psoriasis (n=414)	No Psoriasis (n=15,319)	P value
Age (years)	41.72 ± 11.44	38.20 ± 12.21	<0.001
BMI (kg/m^2)	30.06 ± 7.43	28.90 ± 7.12	0.001
PIR	2.64 ± 1.70	2.51 ± 1.62	0.102
ETA (g/d)	0.14 ± 0.10	0.16 ± 0.11	0.033
EPA (g/d)	0.04 ± 0.11	0.04 ± 0.09	0.131
DHA (g/d)	0.08 ± 0.16	0.07 ± 0.15	0.319
Gender			0.708
Male	190 (45.89%)	7173 (46.82%)
Female	224 (54.11%)	8146 (53.18%)
Veteran status			0.001
Yes	42 (10.14%)	960 (6.27%)
No	372 (89.86%)	14,359 (93.73%)
Marital status			<0.001
Married	253 (61.11%)	8980 (58.62%)
Widowed/ Divorced/ Separated	75 (18.12%)	2116 (13.81%)
Never married	79 (19.08%)	3462 (22.60%)
Drinking alcohol			0.082
Yes	301 (72.71%)	10,341 (67.50%)
No	86 (20.77%)	3751 (24.49%)
Smoking			<0.001
Yes	110 (26.57%)	3553 (23.19%)
No	107 (25.85%)	2607 (17.02%)

Abbreviations: g/d, gram per day; BMI, body mass index; PIR, ratio of family income to poverty; ETA, eicosatetraenoic acid (20:4 n-3); EPA, eicosapentaenoic acid (20:5 n-3); DHA, docosahexaenoic acid (22:6 n-3).

Table 2 Univariate and Multivariate Logistic Regression Model of Daily Dietary N3 Polyunsaturated Fatty Acids Intakes and Psoriasis

Exposure	Model 1 OR (95% CI) P-value	Model 2 OR (95% CI) P-value	Model 3 OR (95% CI) P-value
ETA	0.36 (0.14, 0.92) 0.033	0.35 (0.13, 0.94) 0.037	0.30 (0.12, 0.88) 0.019
EPA	1.97 (0.82, 4.76) 0.132	1.79 (0.72, 4.43) 0.208	1.92 (0.78, 4.74) 0.158
DHA	1.33 (0.76, 2.32) 0.318	1.22 (0.69, 2.17) 0.500	1.28 (0.72, 2.27) 0.408

Notes: Model 1: no covariates were adjusted. Model 2: gender, age, veteran, marital status, PIR were adjusted. Model 3: gender, age, veteran, marital status, PIR, BMI, drinking alcohol, smoking were adjusted.

Abbreviations: ETA, eicosatetraenoic acid (20:4 n-3); EPA, eicosapentaenoic acid (20:5 n-3); DHA, docosahexaenoic acid (22:6 n-3).

Figure 3 Smooth curve fittings show the relationship between daily dietary eicosatetraenoic acid (ETA, 20:4 n-3) intake and the risk of psoriasis overall (A) and within all subgroups (B–I). The red line presents the OR value of the association of ETA and psoriasis, and the blue lines present the 95% confidence interval (A). Smooth curve fittings from (B–I) show the association in different subgroups stratified by each covariate, and each line presents the OR value of the association without a 95% confidence interval. All smooth curve fittings show that the risk of psoriasis decreased linearly with the increase in daily dietary ETA intake overall and within all subgroups. The association was adjusted for gender, age, veteran, marital status, PIR, BMI, drinking alcohol, smoking except the stratified covariate.

Table 3 Trend Test of Association of Daily Dietary ETA Intakes with Psoriasis

	Model 1 OR (95% CI)	Model 2 OR (95% CI)	Model 3 OR (95% CI)
Quintiles of ETA
Q1 (0–0.07 g/d)	Reference	Reference	Reference
Q2 (0.07–0.11 g/d)	0.89 (0.66, 1.20)	0.90 (0.67, 1.21)	0.88 (0.65, 1.19)
Q3 (0.11–0.16 g/d)	0.85 (0.63, 1.15)	0.86 (0.63, 1.15)	0.83 (0.61, 1.12)
Q4 (0.16–0.23 g/d)	0.82 (0.61, 1.11)	0.82 (0.60, 1.11)	0.79 (0.58, 1.07)
Q5 (0.23–1.49 g/d)	0.71 (0.52, 0.97)	0.71 (0.51, 0.98)	0.68 (0.49, 0.94)
P for trend	0.032	0.037	0.016

Notes: Model 1: no covariates were adjusted. Model 2: gender, age, veteran, marital status, PIR were adjusted. Model 3: gender, age, veteran, marital status, PIR, BMI, drinking alcohol, smoking were adjusted.

Abbreviations: ETA, eicosatetraenoic acid (20:4 n-3).

Table 4 Interaction Test of Association of Daily Dietary ETA Intakes with Psoriasis

Subgroups	Model 1 OR (95% CI)	Model 2 OR (95% CI)	Model 3 OR (95% CI)
Stratified by gender
Male (n=7363) (0.19±0.13 g/d)	0.27 (0.08, 0.96)	0.27 (0.08, 0.96)	0.24 (0.07, 0.88)
Female (n=8370) (0.13±0.09 g/d)	0.51 (0.11, 2.39)	0.53 (0.11, 2.50)	0.42 (0.09, 2.01)
P interaction	0.529	0.501	0.600
Stratified by age
18–39 y, (n=8278) (0.16±0.11 g/d)	0.91 (0.24, 3.39)	0.91 (0.24, 3.48)	0.82 (0.21, 3.18)
40–60 y, (n=7455) (0.16±0.11 g/d)	0.16 (0.04, 0.61)	0.15 (0.04, 0.58)	0.12 (0.03, 0.49)
P interaction	0.070	0.061	0.052
Stratified by veteren
Yes (n=1002) (0.16±0.11 g/d)	0.53 (0.04, 6.82)	0.54 (0.04, 7.03)	0.56 (0.04, 7.25)
No (n=14,731) (0.16±0.11 g/d)	0.30 (0.11, 0.83)	0.33 (0.11, 0.94)	0.28 (0.09, 0.80)
P interaction	0.690	0.722	0.625
Stratified by PIR
PIR <2.50 (n=9076) (0.16±0.12 g/d)	0.20 (0.05, 0.75)	0.20 (0.05, 0.76)	0.18 (0.05, 0.70)
PIR≧2.5 (n=6657) (0.15±0.11 g/d)	0.71 (0.19, 2.73)	0.67 (0.17, 2.68)	0.55 (0.14, 2.25)
P interaction	0.184	0.207	0.251
Stratified by marital status
Married (n=9233) (0.15±0.11 g/d)	0.48 (0.14, 1.62)	0.46 (0.13, 1.59)	0.39 (0.11, 1.37)
Widowed/Divorced/Separated (n=2191) (0.15±0.12 g/d)	0.25 (0.03, 2.48)	0.21 (0.02, 2.16)	0.18 (0.02, 1.93)
Never married (n=3541) (0.16±0.12 g/d)	0.23 (0.03, 1.94)	0.21 (0.02, 1.82)	0.19 (0.02, 1.67)
P interaction	0.777	0.743	0.771
Stratified by BMI
BMI<28 kg/m^2 (n=8219) (0.15±0.11 g/d)	0.44 (0.11, 1.78)	0.45 (0.11, 1.88)	0.44 (0.11, 1.85)
BMI≧28 kg/m^2 (n=7514) (0.16±0.12 g/d)	0.27 (0.07, 0.97)	0.25 (0.07, 0.93)	0.24 (0.06, 0.91)
P interaction	0.609	0.544	0.538
Stratified by drinking alcohol
Yes (n=10,642) (0.16±0.12 g/d)	0.26 (0.09, 0.79)	0.27 (0.08, 0.84)	0.24 (0.07, 0.75)
No (n=3837) (0.14±0.10 g/d)	0.88 (0.11, 7.18)	0.99 (0.12, 8.14)	0.80 (0.09, 6.76)
P interaction	0.325	0.290	0.331
Stratified by smoking
Yes (n=3663) (0.16±0.12 g/d)	0.41 (0.07, 2.29)	0.41 (0.07, 2.40)	0.37 (0.06, 2.19)
No (n=2714) (0.16±0.11 g/d)	0.08 (0.01, 0.62)	0.09 (0.01, 0.74)	0.07 (0.01, 0.61)
P interaction	0.225	0.185	0.169

Notes: Model 1: no covariates were adjusted. Model 2: gender, age, veteran, marital status, PIR were adjusted except the covariate that was stratified in the analysis. Model 3: gender, age, veteran, marital status, PIR, BMI, drinking alcohol, smoking were adjusted except the covariate that was stratified in the analysis.

Abbreviations: g/d, gram per day; BMI, body mass index; PIR, ratio of family income to poverty; ETA, eicosatetraenoic acid (20:4 n-3).