Table 3.
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, 2003–2006. And estimated mean difference between National Health and Nutrition Examination Survey 2017–2018 and 2003–2006.
| Variables | Variable Categories | n1 | 2003–06 Prevalence (95% CI) | 2003–06 Mean (95% CI) | Mean Difference 2017–18 minus 2003–06 (95% CI) | p-value of Mean Differences2 |
|---|---|---|---|---|---|---|
| (%) | (μmol/L) | (μmol/L) | ||||
| Age (years) | Overall ≥20 | 8,892 | 7.0 (5.7, 8.5) | 54.0 (52.4, 55.5) | −2.74 (−5.89, 0.41) | 0.09 |
| 20–39 | 3,233 | 6.9 (5.4, 8.9) | 51.0 (48.8, 53.2) | −2.55 (−6.24, 1.14) | 0.17 | |
| 40–59 | 2,635 | 8.1 (6.3, 10.5) | 51.6 (49.7, 53.4) | −2.19 (−5.66, 1.28) | 0.21 | |
| ≥60 | 3,024 | 5.1 (3.8, 6.8) | 63.0 (61.5, 64.6) | −6.23 (−10.1, −2.35) | 0.0023 | |
| Sex | Men | 4,296 | 8.7 (7.0, 10.7) | 49.4 (47.7, 51.0) | −3.31 (−6.48, −0.13) | 0.0415 |
| Women | 4,596 | 5.4 (4.3, 6.8) | 58.3 (56.5, 60.0) | −2.23 (−5.77, 1.30) | 0.21 | |
| Race/Hispanic Origin | Mexican American | 1,799 | 3.9 (2.6, 5.8) | 51.3 (48.9, 53.8) | −1.61 (−6.53, 3.32) | 0.51 |
| Non-Hispanic Black | 1,840 | 5.7 (4.3, 7.6) | 50.3 (48.3, 52.2) | −2.87 (−6.59, 0.86) | 0.13 | |
| Non-Hispanic White | 4,616 | 8.0 (6.5, 9.8) | 54.9 (52.9, 56.9) | −2.15 (−6.64, 2.34) | 0.15 | |
| Poverty Income Ratio | Low (0 – 1.85) | 3,455 | 9.7 (8.0, 11.6) | 49.2 (47.4, 51.1) | −2.94 (−6.99, 1.11) | 0.15 |
| Middle (1.86 – 3.5) | 2,246 | 7.6 (5.9, 9.8) | 53.6 (51.6, 55.6) | −1.46 (−5.91, 2.99) | 0.51 | |
| High (>3.5) | 2,749 | 4.7 (3.6, 6.1) | 57.6 (55.9, 59.3) | −3.41 (−7.21, 0.39) | 0.08 | |
| Body Mass Index3 (kg/m2) | Healthy (18.5 – 24.99) | 2,552 | 6.2 (4.9, 7.9) | 59.6 (57.6, 61.7) | −3.50 (−8.12, 1.12) | 0.13 |
| Overweight (25 – 29.99) | 3,053 | 5.8 (4.7, 7.3) | 55.4 (53.7, 57.2) | 0.43 (−2.45, 3.32) | 0.76 | |
| Obesity (≥30) | 2,996 | 8.5 (6.6, 10.8) | 47.4 (45.7, 49) | −1.97 (−5.32, 1.39) | 0.24 | |
| Dietary Intake Quartiles (mg/day) | (0 – <20) | 1,775 | 14.2 (11.6, 17.2) | 43.2 (40.7, 45.7) | −2.01 (−6.43, 2.42) | 0.37 |
| (20 – <50) | 2,068 | 9.0 (7.2, 11.1) | 48.2 (46.1, 50.2) | −2.63 (−6.62, 1.35) | 0.19 | |
| (50 – <110) | 2,084 | 4.2 (3.0, 5.8) | 57.2 (55.7, 58.7) | −1.03 (−4.06, 2.00) | 0.50 | |
| ≥110 | 2,551 | 1.7 (1.1, 2.6) | 65.8 (64.1, 67.5) | −2.54 (−6.22, 1.13) | 0.17 | |
| Vitamin C-containing Supplement Use | Yes | 3,603 | 1.7 (1.3, 2.3) | 66.7 (65.4, 68.1) | −0.39 (−3.29, 2.51) | 0.79 |
| No | 5,176 | 11.2 (9.2, 13.6) | 43.8 (41.9, 45.8) | −1.32 (−4.52, 1.88) | 0.41 | |
| Smoking Status | Non-smokers | 6,562 | 3.6 (2.8, 4.6) | 58.8 (57.5, 60.0) | −4.07 (−7.21, −0.93) | 0.0122 |
| Smokers | 2,324 | 15.4 (13.1, 18.0) | 42.1 (40.2, 44.1) | −2.19 (−5.72, 1.34) | 0.22 |
1
n refers to sample size in NHANES 2003–2006
2
Student’s t statistic with 45 degrees of freedom
3
Relative CI width for underweight was greater than 130%. Estimate was suppressed (23).