Table 1.
For the US population 20 years and older, weighted prevalence (in percent) of vitamin C deficiency (serum vitamin C <11.4 μmol/L) and weighted mean serum vitamin C concentrations, National Health and Nutrition Examination Survey, 2017–2018
| Variables | Variable Categories | n | Prevalence (95% CI)1 | Wald F | Mean (95% CI)1 | Wald F |
|---|---|---|---|---|---|---|
| (%) | p-value2 | (μmol/L) | p-value2 | |||
| Age (years) | Overall ≥20 | 4,932 | 6.8 (5.0, 9.0) | 0.69 | 51.2 (48.3, 54.1) | 0.0005 |
| 20–39 | 1,463 | 6.2 (4.1, 9.3) | 48.4 (45.3, 51.6)a | |||
| 40–59 | 1,563 | 7.0 (5.1, 9.5) | 49.4 (46.3, 52.5)a | |||
| ≥60 | 1,906 | 7.2 (5.1, 9.9) | 56.8 (53.0, 60.6)b | |||
| Sex | Men | 2,377 | 7.7 (5.5, 10.6) | 0.10 | 46.1 (43.2, 48.9)a | <0.0001 |
| Women | 2,555 | 5.9 (4.3, 8.1) | 56.0 (52.8, 59.3)b | |||
| Race/Hispanic Origin | Mexican American | 675 | 4.5 (2.6, 7.7)a,b | 0.0313 | 49.7 (45.0, 54.4)a,b | 0.0085 |
| Non-Hispanic Asian | 693 | 3.0 (2.2, 4.1)b | 54.6 (51.6, 57.6)b | |||
| Non-Hispanic Black | 1,117 | 6.0 (3.5, 10.0)a,b | 47.4 (44.0, 50.8)a | |||
| Non-Hispanic White | 1,728 | 7.7 (5.5, 10.6)a | 52.2 (48.8, 55.6)a,b | |||
| Poverty Income Ratio | Low (0 – 1.85) | 1,893 | 9.8 (6.9, 13.6)a | 0.002 | 46.3 (42.5, 50.1)a | 0.0004 |
| Middle (1.86 – 3.5) | 1,095 | 6.7 (4.5, 10.0)a,b | 52.1 (47.9, 56.4)b | |||
| High (>3.5) | 1,304 | 4.6 (3.0, 6.8)b | 54.2 (50.6, 57.8)b | |||
| Body Mass Index3 (kg/m2) | Healthy (18.5 – 24.99) | 1,173 | 7.6 (5.2, 11.1)a,b | 0.0154 | 56.1 (51.7, 60.5)a | <0.0001 |
| Overweight (25 – 29.99) | 1,563 | 4.4 (3.0, 6.4)a | 55.9 (53.4, 58.3)a | |||
| Obesity (≥30) | 2,049 | 7.7 (5.5, 10.5)b | 45.4 (42.3, 48.5)b | |||
| Dietary Intake Quartiles (mg/day) | (0 – <20) | 1,163 | 13.9 (10.5, 18.3)a | <0.0001 | 41.2 (37.3, 45.0)a | <0.0001 |
| (20 – <50) | 1,139 | 7.4 (5.2, 10.4)b | 45.5 (41.9, 49.2)b | |||
| (50 – <110) | 1,095 | 2.9 (1.9, 4.6)c | 56.2 (53.4, 59.0)c | |||
| ≥110 | 1,085 | 2.2 (1.1, 4.2)c | 63.3 (59.8, 66.7)d | |||
| Vitamin C-containing Supplement Use | Yes | 1,133 | 0.5 (0.2, 1.5)a | <0.0001 | 70.6 (67.5, 73.7)a | <0.0001 |
| No | 3,336 | 9.2 (6.9, 12.1)b | 43.5 (40.9, 46.2)b | |||
| Smoking Status | Non-smokers | 3,751 | 4.4 (3.2, 5.9)a | 0.0002 | 54.7 (51.6, 57.7)a | <0.0001 |
| Smokers | 1,162 | 14.6 (10.6, 19.8)b | 39.9 (36.8, 43.1)b |
Compact letter display is used to show statistically significant differences between pairwise comparisons after Bonferroni adjustment. Categories sharing one or more letters were not significantly different. Pairwise comparisons were only assessed if the null hypothesis of equality among the prevalences across the categories was rejected at 0.05 significance level.
P-value based on Wald F test, which tests whether at least one of the prevalences or means across the categories were significantly different
Relative CI width for underweight was greater than 130%. Estimate was suppressed (23).