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Table 1 Characteristics of participants aged 50 years and older in NHANES 2011–14 based on serum zinc concentration tertile (total n = 1136)

From: Association between serum zinc levels and basic physical functioning: secondary data analysis of NHANES 2011–14

Variables+ Low Zn tertile (N = 404) Middle Zn tertile (N = 380) High Zn tertile (N = 352) P value
Mean Zn level (+/−SE) (μg/mL)§ 0.67 (±0.01) 0.81 (±0.01) 0.98 (±0.01)  
range 0.409–0.748 0.749–0.870 0.872–1.698  
Basic physical functioning difficulty     0.036
 Yes (n = 283) 102 (34.2%) 105 (40.0%) 76 (25.8%)  
 No (n = 853) 302 (33.8%) 275 (30.7%) 276 (35.5%)  
Age (+/− SE) years 67.3+/− 0.5 66.9+/− 0.7 66.1+/− 0.4 0.186
(95% CI) (66.2–68.4) (65.5–68.4) (65.4–66.9)  
Sex     0.016
 Male (n = 561) 203 (32.5%) 172 (27.2%) 186 (40.4%)  
 Female (n = 575) 201 (35.2%) 208 (37.7%) 166 (27.1%)  
BMI
 Under (n = 19) 6 (15.8%)+ 10 (69.1%)+ 3 (15.1%)+ 0.031
 Normal (n = 301) 108 (35.1%) 98 (33.3%) 95 (31.6%)  
 Overweight (n = 400) 131 (29.5%) 136(33.0%) 133 (37.4%)  
 Obese (n = 416) 159 (38.6%) 136(30.2%) 121 (31.2%)  
Race/ethnicity     0.516
 Non-Hispanic White (n = 533) 186 (33.7%) 174(32.0%) 173 (34.3%)  
 Non-Hispanic Black (n = 261) 102 (39.3%) 87 (31.4%) 72 (29.3%)  
 Others (n = 342) 116 (31.8%) 119 (37.6%) 107 (30.6%)  
Education     0.786
  < High school (n = 352) 125 (31.6%) 118(37.0%) 109 (31.5%)  
  = High school (n = 253) 87 (34.0%) 83 (31.8%) 83 (34.2%)  
  > High school (n = 531) 192 (34.6%) 179 (31.7%) 160 (33.7%)  
Heath insurance     0.599
 Yes (n = 1001) 361 (34.5%) 339 (32.6%) 301 (32.9%)  
 No (n = 135) 43(28.8%) 41 (33.4%) 51 (37.8%)  
Drinker     0.225
 Yes (n = 605) 202 (33.6%) 219 (34.7%) 184 (31.7%)  
 No (n = 531) 202 (34.4%) 161 (29.5%) 168 (36.1%)  
Smoking     0.483
 Never (n = 541) 208 (36.5%) 179 (32.0%) 154 (31.5%)  
 Former (n = 410) 128 (30.6%) 143 (33.9%) 139 (35.6%)  
 Current (n = 185) 68 (34.2%) 58 (31.9%) 59 (33.9%)  
Physical activity     0.528
 Yes (n = 405) 134 (31.8%) 135 (32.4%) 136 (35.8%)  
 No (n = 731) 270 (35.3%) 245 (32.9%) 216 (31.8%)  
Diabetes     0.252
 Yes (n = 277) 93 (30.7%) 89 (29.8%) 95 (39.5%)  
 No (n = 859) 311 (34.8%) 291 (33.5%) 257(31.7%)  
Serum albumin+     < 0.01 between groups
 (mean +/− SE) (gm/dL) 4.11+/−0.02 4.23+/−0.02 4.32+/−0.02
 (95% CI) (4.07–4.14) (4.19–4.27) (4.27–4.37)
Hemoglobin     < 0.001
 (mean +/− SE) (gm/dL) 13.6+/−0.1 14.0+/− 0.1 14.1+/− 0.1  
 (95% CI) (13.4–13.8) (13.8–14.1) (14.1–14.6)  
  1. + All percentages reported here are based on a weighted percentage
  2. § converting to SI unit (μmol/L) by multiplying 15.3
  3. + converting to SI unit (g/L) by multiplying 10
  4. Abbreviation: BMI = body mass index