Background
Methods
Study design
Characteristics |
N (%) | Mean ± SD (range) |
---|---|---|
All | 95 (100) | |
Males | 43 (45) | |
Females | 52 (55) | |
Age (years) | 95 (100) | 35.6 ± 10.8 (18-60) |
<30 | 31 (32.6) | |
31–40 | 41 (43.2) | |
41–50 | 9 (9.5) | |
51–60 | 14 (14.7) | |
BMI (kg/m2) | 95 (100) | 23.8 ± 3.1 (17.9-34.9) |
<25 | 68 (71.6) | |
25–30 | 23 (24.2) | |
>30 | 4 (4.2) | |
Smoking | ||
Current | 0 (0) | |
Ever | 25 (26.3) | |
In the past 5 years | 10 (9.5) | |
Never | 70 (73.7) | |
Passive smoking | ||
Yes | 25 (26.3) | |
No | 70 (73.7) | |
Alcohol consumption | ||
Never | 5 (5.3) | |
Less than 1 day per month | 30 (31.6) | |
Less than 1 day per week | 34 (35.8) | |
Up to 2 days per week | 25 (26.3) | |
3–5 days per week or more | 1 (1.1) | |
Vitamin or mineral supplements use | ||
Yes, sporadically | 34 (35.8) | |
Yes, regularly | 23 (24.2) | |
No | 38 (40.0) | |
Selenium containing supplements use in the past 6 months | ||
Yes | 5 (5.3) | |
No | 90 (94.7) |
Genotype |
N (%) | Age, years (median and range) | Sex (females/males) | BMI (median and range) | Plasma Se, µg/L (median and range) | Plasma Sepp1 ng/mL (median and range) * |
---|---|---|---|---|---|---|
GPX1 rs1050450 | ||||||
Pro/Pro | 39 (41 %) | 33.0 (18.0–60.0) | 1.29 (22/17) | 22.9 (18.0–33.1) | 63.3 (34.3–109.1) | 3.9 (0.9–26.4) |
Pro/Leu | 35 (37 %) | 37.0 (18.0–58.0) | 1.06 (18/17) | 23.7 (17.9–31.1) | 62.7 (35.8–103.2) | 4.2 (1.3–36.0) |
Leu/Leu | 21 (22 %) | 34.0 (18.0–58.0) | 1.33 (12/9) | 24.6 (20.1–34.9) | 62.5 (37.2–96.2) | 3.6 (1.0–6.4) |
SEPP1 rs3877899 | ||||||
Ala/Ala | 46 (48 %) | 33.0 (20.0–58.0) | 0.92 (22/24) | 23.4 (18.7–31.1) | 66.3 (37.2–106.1)a
| 3.1 (1.0–26.9) |
Ala/Thr | 29 (31 %) | 33.0 (18.0–58.0) | 1.90 (19/10) | 22.9 (17.9–27.7) | 68.9 (34.3–96.2)a
| 4.2 (0.9–36.0) |
Thr/Thr | 20 (21 %) | 36.5 (18.0–60.0) | 1.22 (11/9) | 23.7 (18.9–34.9) | 52.0 (35.8–109.1)a
| 4.3 (1.1–23.4) |
DNA isolation and SNP genotyping
mRNA isolation, cDNA synthesis, and gene expression
Plasma selenium concentration
Plasma selenoprotein P concentration
Activity of antioxidant enzymes
Total antioxidant capacity
Lipid peroxidation
Oxidative burst
DNA damage
Statistical analysis
Results
Course of the study
Sex and genotype differences at baseline
Se supplementation effects
Marker | Median and range, measured at four different time points |
p value (MANCOVA)** | |||
---|---|---|---|---|---|
Baseline | 2 weeks | 6 weeks | Washout | ||
Se (µg/L) | 62.65a
(34.32–109.12) |
98.00
b
(56.49–183.86) |
93.84
b
(54.92–148.76) |
74.61
c
(49.27–111.58) |
p < 0.0001
|
Sepp1 * (ng/mL) | 3.86a
(0.86–36.03) |
7.36
b
(0.97–41.60)
|
6.14
c
(0.26–34.08) |
6.00
c
(0.66–31.20) |
p < 0.0001
|
GPx1 (U/gHb) | 17.10a
(9.68–29.04) | 16.24a
(8.93–28.17) |
24.43
b
(11.95–29.88)
|
23.76
b
(14.03–29.96)
|
p < 0.0001
|
GPx3 (U/mL) | 0.18a
(0.12–0.25) | 0.18a
(0.12–0.26) |
0.20
b
(0.14–0.28)
|
0.19
c
(0.12–0.26) |
p < 0.0001
|
SOD1 (U/mg Hb) | 6.20 (3.93–8.39) | 6.12 (3.04–9.38) | 6.02 (4.34–8.50) | 6.00 (3.93–8.75) |
p = 0.21 |
Cp (g/L) | 0.46a
(0.24–0.91) |
0.49
b
(0.30–0.87)
|
0.48
b
(0.34–0.79)
|
0.49
b
(0.34–0.78)
|
p = 0.01
|
TAC * (mmol/L) | 0.85a
(0.03–5.08) |
1.18
b
(0.10–4.99)
|
1.36
c
(0.05–5.25)
|
2.02
d
(0.24–5.95)
|
p < 0.0001
|
TBARS * (mmol/mL) | 1.75a
(1.00–4.08) |
1.98
b
(1.02–4.24)
|
2.02
b
(1.02–4.52) |
2.08
b
(1.01–3.29) |
p < 0.0001
|
RFT (MFI index) | 78.90a
(22.35 ± 134.12) |
67.66
b
(32.18 ± 113.57) | na | na |
p < 0.0001
|
DNA strand breaks (% tail DNA)* | 1.86a
(0.57–5.50) | na | 1.91a
(0.63–3.90) |
2.10
b
(1.02–6.08) |
p < 0.0001
|
DNA oxidation (% tail DNA) | 2.58a
(0.00–5.74) | na | 2.35a,b
(0.00–6.23) |
3.08
c
(0.00–6.49) |
p < 0.0001
|
Gene | Mean and SD, measured at four different time points |
p value, (MANCOVA)* | |||
---|---|---|---|---|---|
Baseline | 2 weeks | 6 weeks | Washout | ||
GPX1
| 1.425 ± 0.212a
| 1.411 ± 0.187a
|
1.355 ± 0.194
b
|
1.292 ± 0.208
c
|
p < 0.0001
|
GPX4
| 1.355 ± 0.217a
|
1.294 ± 0.189
b
|
1.284 ± 0.193
b
|
1.251 ± 0.206
c
|
p = 0.002
|
TRXR1
| 1.742 ± 0.226 | 1.721 ± 0.197 | 1.748 ± 0.195 | 1.736 ± 0.208 |
p = 0.60 |
SEPP1
| 1.555 ± 0.292a,c
| 1.590 ± 0.316a,b
| 1.620 ± 0.284a,b
| 1.467 ± 0.318a,c
|
p = 0.001
|
SEP15
| 1.625 ± 0.179a
|
1.579 ± 0.181
b
|
1.526 ± 0.165
c
|
1.536 ± 0.223
c
|
p < 0.001
|
SELS
| 2.039 ± 0.274a
| 1.977 ± 0.245a
|
1.916 ± 0.217
b
|
1.886 ± 0.309
b
|
p < 0.0001
|
SELW
| 1.220 ± 0.218a
| 1.183 ± 0.218a,b
|
1.115 ± 0.213
b
|
1.125 ± 0.250
b
|
p = 0.0003
|
SBP2
| 1.470 ± 0.212 | 1.476 ± 0.183 | 1.472 ± 0.233 | 1.493 ± 0.210 |
p = 0.73 |
SNP alone effects and the interaction with Se supplementation
Parameter |
p value for genotype effect (ANCOVA)* and for time interaction (MANCOVA)* | ||
---|---|---|---|
GPX1 rs1050450 |
SEPP1 rs3877899 |
GPX1 rs1050450 × SEPP1 rs3877899 | |
Se (µg/L) |
p = 0.94 |
p = 0.08 |
p = 0.36 |
Sepp1** (ng/mL) |
p = 0.17 |
p = 0.13 |
p = 0.84 |
GPx1 (U/gHb) |
p = 0.04
(Fig. 1a) |
p = 0.33 |
p = 0.59 |
GPx3 (U/mL) |
p = 0.47 Interaction with time: |
p = 0.33 |
p = 0.48 |
SOD1 (U/mg Hb) |
p = 0.91a
|
p = 0.76 Interaction with time: |
p = 0.64 |
Cp (g/L) |
p = 0.20 |
p = 0.70 |
p = 0.33 |
TAC** (mmol/L) |
p = 0.76 |
p = 0.37 |
p = 0.97 |
TBARS** (mmol/mL) |
p = 0.09 |
p = 0.15 |
p = 0.65 |
RFT (MFI index) |
p = 0.14 |
p = 0.95 |
p = 0.74 |
DNA strand breaks (% tail DNA) |
p = 0.49 Interaction with time:
p = 0.05
(Fig. 4) |
p = 0.72 |
p = 0.47 |
DNA oxidation (% tail DNA) |
p < 0.0001
(Fig. 5) |
p = 0.62 |
p = 0.65 |