Table 1.
General characteristics of participants (n = 4494) stratified by vitamin C (quartiles1-4, umol/L) in the NHANES 2017–2018.
| Characters | Total (n = 4494) | Quartiles 1 (<30.9) (n = 1121) | Quartiles 2 (30.9–50.5) (n = 1124) | Quartiles 3 (50.5–67.0) (n = 1096) | Quartiles 4 (≥67.0) (n = 1153) | p-Value |
|---|---|---|---|---|---|---|
| Age (years) | 47.13 ± 17.49 | 45.94 ± 16.74 | 45.26 ± 16.81 | 46.20 ± 17.18 | 50.73 ± 18.49 | <0.001 |
| 18~39 | 38.37 (36.27–40.52) | 37.77 (33.67–42.04) | 43.13 (38.86–47.50) | 40.96 (36.54–45.52) | 32.43 (28.63–36.47) | |
| 40~59 | 34.09 (31.92–36.34) | 37.20 (32.88–41.74) | 34.44 (30.14–39.00) | 33.28 (28.92–37.95) | 31.60 (27.48–36.03) | |
| 60~80 | 27.53 (25.65–29.50) | 25.04 (21.62–28.80) | 22.43 (19.08–26.18) | 25.76 (22.02–29.90) | 35.97 (32.01–40.12) | |
| Gender | <0.001 | |||||
| Men | 49.15 (46.93–51.38) | 56.73 (52.36–61.00) | 54.39 (49.96–58.75) | 54.16 (49.57–58.68) | 32.74 (28.74–37.00) | |
| Women | 50.85 (48.62–53.07) | 43.27 (39.00–47.64) | 45.61 (41.25–50.04) | 45.84 (41.32–50.43) | 67.26 (63.00–71.26) | |
| Race/ethnicity | <0.001 | |||||
| Hispanic | 16.44 (15.27–17.68) | 11.94 (10.05–14.12) | 21.67 (18.95–24.66) | 18.16 (15.70–20.90) | 14.61 (12.56–16.93) | |
| Non-Hispanic White | 62.61 (60.71–64.47) | 68.11 (64.57–71.44) | 52.34 (48.01–56.64) | 59.94 (55.84–63.91) | 68.74 (65.41–71.88) | |
| Non-Hispanic Black | 10.54 (9.75–11.39) | 10.52 (9.07–12.16) | 13.43 (11.60–15.49) | 10.64 (9.05–12.48) | 7.97 (6.70–9.46) | |
| Non-Hispanic Asian | 5.67 (5.18–6.21) | 3.48 (2.76–4.38) | 7.08 (5.93–8.43) | 6.27 (5.26–7.46) | 5.99 (5.06–7.08) | |
| Other racesa | 4.74 (3.91–5.73) | 5.96 (4.23–8.35) | 5.49 (3.70–8.06) | 4.99 (3.45–7.15) | 2.69 (1.72–4.19) | |
| Education | <0.001 | |||||
| More than high school | 60.93 (58.80–63.02) | 50.49 (46.10–54.88) | 59.56 (55.24–63.74) | 64.28 (59.93–68.41) | 68.93 (65.04–72.57) | |
| High school or equivalent | 27.61 (25.66–29.64) | 35.19 (31.08–39.54) | 26.48 (22.68–30.66) | 26.54 (22.68–30.78) | 22.35 (19.02–26.09) | |
| Less than high school | 11.39 (10.40–12.46) | 14.31 (12.04–16.94) | 13.74 (11.58–16.24) | 9.13 (7.55–11.00) | 8.68 (7.18–10.46) | |
| Not recorded | 0.07 (0.03–0.16) | - | 0.21 (0.07–0.62) | 0.05 (0.01–0.21) | 0.03 (0.00–0.25) | |
| Poverty-income ratio | <0.001 | |||||
| <1.3 | 18.19 (16.85–19.61) | 22.48 (19.73–25.49) | 19.44 (16.56–22.68) | 15.73 (13.25–18.58) | 15.32 (13.02–17.94) | |
| 1.3–1.8 | 8.20 (7.35–9.15) | 9.52 (7.70–11.72) | 8.24 (6.53–10.33) | 8.24 (6.61–10.22) | 6.89 (5.51–8.58) | |
| >1.8 | 63.57 (61.60–65.51) | 57.76 (53.63–61.79) | 60.92 (56.72–64.97) | 67.96 (64.08–71.61) | 67.29 (63.57–70.81) | |
| Not recorded | 10.04 (8.88–11.32) | 10.23 (8.07–12.89) | 11.40 (8.87–14.55) | 8.07 (6.20–10.44) | 10.50 (8.32–13.17) | |
| BMI group | <0.001 | |||||
| <25 | 27.60 (25.63–29.65) | 23.73 (20.23–27.63) | 23.31 (19.68–27.37) | 25.69 (21.80–30.00) | 36.76 (32.65–41.08) | |
| 25–30 | 31.50 (29.47–33.60) | 21.96 (18.65–25.67) | 30.99 (27.07–35.19) | 39.11 (34.66–43.76) | 33.91 (29.93–38.13) | |
| ≥30 | 40.40 (38.24–42.60) | 53.36 (48.97–57.70) | 45.34 (40.98–49.78) | 34.89 (30.69–39.33) | 28.95 (25.25–32.95) | |
| Not recorded | 0.50 (0.33–0.77) | 0.96 (0.48–1.88) | 0.36 (0.14–0.92) | 0.31 (0.14–0.66) | 0.38 (0.15–1.01) | |
| Physical activity level | <0.001 | |||||
| Inactive | 50.77 (48.54–53.00) | 49.74 (45.34–54.14) | 46.94 (42.56–51.36) | 49.34 (44.73–53.96) | 56.39 (52.03–60.65) | |
| Less active | 7.43 (6.31–8.73) | 5.93 (4.27–8.18) | 7.94 (5.71–10.94) | 8.61 (6.25–11.75) | 7.33 (5.30–10.05) | |
| Active | 41.80 (39.61–44.02) | 44.33 (40.00–48.75) | 45.12 (40.74–49.58) | 42.05 (37.56–46.68) | 36.28 (32.19–40.58) | |
| Daily alcohol drinking status | <0.001 | |||||
| Non-drinkers | 7.53 (6.50–8.71) | 7.49 (5.52–10.08) | 6.82 (5.25–8.82) | 7.22 (5.18–9.98) | 8.48 (6.48–11.03) | |
| Moderate-drinkers | 29.66 (27.58–31.82) | 26.48 (22.50–30.89) | 27.55 (23.53–31.97) | 31.72 (27.43–36.34) | 32.58 (28.64–36.79) | |
| Heavy-drinkers | 14.48 (13.00–16.09) | 14.77 (11.84–18.27) | 15.70 (12.65–19.32) | 12.95 (10.37–16.07) | 14.57 (11.85–17.79) | |
| Binge-drinkers | 32.79 (30.72–34.94) | 34.86 (30.89–39.05) | 36.68 (32.46–41.12) | 33.61 (29.29–38.22) | 26.7 (22.92–30.86) | |
| Not recorded | 15.54 (14.15–17.03) | 16.40 (13.62–19.61) | 13.25 (11.17–15.64) | 14.50 (11.94–17.50) | 17.66 (14.69–21.09) | |
| History of diabetes | <0.001 | |||||
| Yes | 12.82 (11.54–14.22) | 16.57 (13.68–19.93) | 12.87 (10.62–15.51) | 11.31 (8.96–14.19) | 10.62 (8.43–13.29) | |
| Having HBV infection | 0.105 | |||||
| Yes | 0.94 (0.62–1.41) | 0.70 (0.39–1.28) | 1.31 (0.52–3.27) | 1.33 (0.66–2.66) | 0.47 (0.25–0.87) | |
| Having HCV infection | 0.011 | |||||
| Yes | 2.49 (1.83–3.38) | 2.36 (1.57–3.53) | 3.09 (1.67–5.64) | 1.58 (0.79–3.13) | 2.95 (1.52–5.64) | |
| Dietary VC supplement | <0.001 | |||||
| Yes | 38.03 (35.85–40.27) | 13.24 (10.29–16.87) | 33.25 (29.05–37.74) | 40.6 (36.08–45.29) | 63.37 (59.19–67.36) | |
| Daily dose of supplement of VC, mg | <0.001 | |||||
| None | 74.68 (72.60–76.65) | 94.96 (92.92–96.44) | 82.60 (78.57–86.01) | 74.21 (69.83–78.16) | 48.96 (44.65–53.28) | |
| 1–60 | 10.08 (8.81–11.52) | 2.73 (1.70–4.36) | 9.67 (7.21–12.86) | 11.48 (8.88–14.72) | 16.13 (13.17–19.61) | |
| 60–120 | 5.03 (4.04–6.26) | 0.86 (0.37–2.00) | 3.85 (2.28–6.44) | 6.71 (4.46–9.96) | 8.45 (6.17–11.48) | |
| 121–500 | 5.62 (4.60–6.84) | 0.58 (0.25–1.32) | 2.21 (1.01–4.77) | 5.29 (3.45–8.05) | 13.65 (10.81–17.09) | |
| >500 | 4.59 (3.70–5.68) | 0.87 (0.34–2.20) | 1.66 (0.82–3.34) | 2.30 (1.42–3.71) | 12.81 (9.97–16.30) | |
| Monthly dose of supplement of VC, mg | <0.001 | |||||
| None | 67.90 (65.74–69.98) | 89.95 (86.74–92.45) | 71.67 (67.40–75.58) | 65.05 (60.46–69.37) | 46.31 (42.04–50.63) | |
| 1–1800 | 15.28 (13.75–16.94) | 7.32 (5.18–10.26) | 16.58 (13.59–20.09) | 17.08 (13.93–20.76) | 20.05 (16.85–23.69) | |
| 1800–3600 | 5.79 (4.75–7.06) | 1.55 (0.71–3.36) | 6.19 (4.13–9.18) | 8.07 (5.59–11.50) | 7.38 (5.42–9.96) | |
| >3600 | 11.03 (9.66–12.57) | 1.18 (0.57–2.42) | 5.56 (3.76–8.16) | 9.81 (7.42–12.86) | 26.27 (22.49–30.43) | |
| Dietary VC intake by food, mg/d | <0.001 | |||||
| 0–18.5 | 22.73 (20.96–24.61) | 36.05 (31.97–40.33) | 23.24 (19.63–27.27) | 18.21 (15.08–21.82) | 13.86 (11.23–16.97) | |
| 18.5–47.1 | 25.62 (23.66–27.68) | 33.68 (29.63–37.99) | 29.16 (25.25–33.40) | 23.15 (19.16–27.67) | 17.19 (14.00–20.94) | |
| 47.1–106.5 | 24.44 (22.53–26.45) | 17.65 (14.52–21.29) | 26.48 (22.51–30.86) | 24.37 (20.68–28.49) | 29.20 (25.31–33.41) | |
| >106.5 | 21.68 (19.94–23.52) | 8.27 (6.13–11.08) | 15.62 (13.08–18.55) | 28.66 (24.65–33.03) | 33.16 (29.29–37.26) | |
| Not recorded | 5.53 (4.72–6.47) | 4.35 (2.81–6.67) | 5.51 (4.26–7.11) | 5.62 (4.22–7.43) | 6.60 (4.88–8.86) | |
| Laboratory parameters | ||||||
| Smoking (serum cotinine levels, ng/ml) | <0.001 | |||||
| <0.015 | 38.17 (35.97–40.42) | 27.60 (23.52–32.09) | 34.35 (30.23–38.71) | 42.38 (37.80–47.09) | 47.61 (43.29–51.97) | |
| 0.015–3 | 37.41 (35.31–39.56) | 35.32 (31.24–39.62) | 40.29 (36.04–44.69) | 36.37 (32.13–40.84) | 37.90 (33.88–42.09) | |
| ≥3 | 24.04 (22.27–25.90) | 36.86 (32.89–41.01) | 24.47 (20.95–28.37) | 20.83 (17.43–24.70) | 14.47 (11.77–17.68) | |
| Not recorded | 0.37 (0.15–0.90) | 0.23 (0.09–0.58) | 0.89 (0.20–4.00) | 0.42 (0.18–0.95) | 0.01 (0.00–0.10) | |
| ALT (U/L) | 23.26 ± 17.77 | 25.13 ± 22.03 | 24.21 ± 17.75 | 22.14 ± 12.84 | 21.71 ± 16.99 | <0.001 |
| AST (U/L) | 22.31 ± 13.41 | 22.96 ± 18.55 | 22.15 ± 11.94 | 22.06 ± 10.16 | 22.05 ± 11.24 | 0.304 |
| ALB (g/L) | 41.02 ± 3.21 | 40.36 ± 3.36 | 40.99 ± 3.26 | 41.30 ± 3.00 | 41.40 ± 3.12 | <0.001 |
| ALP (U/L) | 76.34 ± 25.33 | 82.37 ± 30.58 | 77.45 ± 24.94 | 73.62 ± 21.67 | 72.19 ± 21.92 | <0.001 |
| GGT (U/L) | 29.71 ± 40.06 | 36.16 ± 55.87 | 34.02 ± 43.07 | 24.79 ± 25.32 | 24.46 ± 27.20 | <0.001 |
| TC (mmol/L) | 4.88 ± 1.04 | 4.89 ± 1.07 | 4.92 ± 1.11 | 4.80 ± 0.97 | 4.91 ± 1.02 | 0.017 |
| TB (umol/L) | 8.14 ± 4.83 | 7.89 ± 4.81 | 8.11 ± 4.62 | 8.40 ± 4.98 | 8.17 ± 4.88 | 0.095 |
| CRP (mg/L) | 3.72 ± 7.16 | 5.14 ± 9.05 | 3.99 ± 8.43 | 3.10 ± 5.64 | 2.72 ± 4.46 | <0.001 |
| Platelet ( ×10∧9/L) | 244.79 ± 61.42 | 247.07 ± 62.84 | 248.08 ± 62.13 | 244.39 ± 63.13 | 240.15 ± 57.40 | 0.010 |
| Transient Elastography | ||||||
| Median stiffness (kPa) | 5.66 ± 4.73 | 6.64 ± 6.79 | 5.48 ± 3.97 | 5.34 ± 4.36 | 5.18 ± 2.71 | <0.001 |
| Controlled attenuation parameter (dB/m) | 262.47 ± 62.70 | 277.89 ± 66.53 | 266.90 ± 60.68 | 257.71 ± 58.25 | 248.41 ± 60.94 | <0.001 |
| NAFLD | <0.001 | |||||
| Yes | 37.23 (35.13–39.39) | 43.76 (39.44–48.18) | 37.25 (33.21–41.48) | 33.91 (29.79–38.28) | 34.11 (30.10–38.37) | |
| MAFLD | <0.001 | |||||
| Yes | 47.98 (45.76–50.21) | 57.39 (52.98–61.68) | 51.24 (46.80–55.66) | 44.13 (39.65–48.71) | 39.81 (35.63–44.15) | |
| Liver fibrosis | <0.001 | |||||
| Yes | 21.23 (19.48–23.08) | 30.58 (26.72–34.74) | 20.47 (17.41–23.90) | 17.15 (14.01–20.83) | 16.79 (13.55–20.62) | |
| Liver cirrhosis | <0.001 | |||||
| Yes | 3.08 (2.35–4.02) | 6.41 (4.44–9.16) | 2.26 (1.28–3.96) | 1.66 (0.98–2.80) | 1.93 (0.82–4.51) | |
Values are weighted mean ± SD or weighted % (95% confidence interval). P-values are weighted.
a
Other races include American Indian or Alaska Native, Native Hawaiian or other Pacific Islander, and multiracial persons.
ALT, alanine aminotransferase; AST, aspartate aminotransferase; ALP, alkaline Phosphatase; ALB, albumin; BMI, body mass index; CRP, C reactive protein; GGT, gamma glutamyl transferase; HBV, hepatitis B virus; HCV, hepatitis C virus; MAFLD, metabolic dysfunction-associated fatty liver disease; NHANES, National Health and Nutrition Examination Survey; NAFLD, non-alcoholic fatty liver disease; TC, total cholesterol; TB, total bilirubin; VC, vitamin C.