Table 1. Participant Characteristics According to Quartile of Plasma Concentration of Vitamin B12.
| Characteristic | Participants, No. (%) | P Valuea | |||
|---|---|---|---|---|---|
| All (N = 5571) | Vitamin B12 Plasma Concentration Quartile | ||||
| 1 (<338.85 pg/mL) (n = 1390) | 2 and 3 (338.85-455.41 pg/mL) (n = 2787) | 4 (>455.41 pg/mL) (n = 1394) | |||
| Men | 2830 (50.8) | 709 (51.0) | 1444 (51.8) | 677 (48.5) | .12 |
| Age, mean (SD), y | 53.5 (12.0) | 52.5 (12.3) | 53.4 (11.9) | 54.6 (11.6) | <.001 |
| White race/ethnicity | 5292 (95.0) | 1326 (95.4) | 2651 (95.1) | 1315 (94.3) | .05 |
| Education levelb | .25 | ||||
| Low | 2455 (44.0) | 589 (42.3) | 1234 (44.3) | 632 (45.4) | |
| Medium | 1415 (25.5) | 383 (27.7) | 697 (25.0) | 335 (24.0) | |
| High | 1701 (30.5) | 418 (30.0) | 856 (3.7) | 427 (30.6) | |
| BMI, mean (SD) | 26.7 (4.3) | 26.4 (4.1) | 26.8 (4.4) | 26.5 (4.4) | <.001 |
| Systolic BP, mean (SD), mm Hg | 126.3 (18.6) | 125.4 (18.4) | 126.1 (18.4) | 127.8 (19.2) | .001 |
| Diastolic BP, mean (SD), mm Hg | 73.5 (9.1) | 72.9 (9.1) | 73.4 (9.1) | 74.2 (9.1) | <.001 |
| Parental history of CKD | 25 (0.5) | 7 (0.5) | 12 (0.4) | 7 (0.5) | .74 |
| Parental history of type 2 diabetes | 854 (15.3) | 203 (14.6) | 429 (15.4) | 222 (15.9) | .49 |
| Type 2 diabetes | 347 (6.2) | 55 (3.95) | 185 (6.63) | 107 (7.67) | <.001 |
| Cancer history | 262 (4.7) | 71 (5.1) | 131 (4.7) | 60 (4.3) | .60 |
| CVD history | 369 (6.6) | 86 (6.2) | 180 (6.4) | 103 (7.3) | .39 |
| Smoking status | |||||
| Never | 1577 (28.3) | 379 (27.3) | 778 (27.9) | 420 (30.1) | .01 |
| Former | 2378 (42.7) | 581 (41.8) | 1180 (42.3) | 617 (44.3) | |
| Current | 1547 (27.8) | 409 (29.4) | 796 (28.6) | 342 (24.5) | |
| Alcohol consumption, drinks/wk | |||||
| <1 | 1424 (25.6) | 352 (25.3) | 707 (25.4) | 365 (26.2) | .04 |
| 1-7 | 2653 (47.6) | 670 (48.2) | 1365 (49.0) | 618 (44.3) | |
| >7 | 1442 (25.9) | 349 (25.1) | 694 (24.9) | 399 (28.6) | |
| Using antihypertensive drugs | 1404 (19.8) | 227 (16.3) | 563 (2.2) | 314 (22.5) | <.001 |
| Using lipid-lowering drugs | 460 (8.2) | 93 (6.7) | 237 (8.5) | 130 (9.3) | .05 |
| Plasma concentration of vitamin B12, median (IQR), pg/mL | 394.42 (310.38-497.42) | 261.59 (226.35-287.34) | 394.42 (352.40-439.14) | 626.19 (532.66-670.91) | <.001 |
| Ferritin, median (IQR), ng/mL | 98.0 (48.0-134.6) | 84.0 (44.0-152.2) | 101.0 (49.0-174.0) | 107.0 (52.0-196.2) | <.001 |
| Transferrin, mean (SD), mg/dL | 259 (40) | 261 (45) | 257 (39) | 258 (39) | .03 |
| Hemoglobin, mean (SD), g/dL | 13.74 (1.22) | 13.65 (1.21) | 13.76 (1.22) | 13.79 (1.22) | .003 |
| Hematocrit, mean (SD), % | 40.88 (3.61) | 40.65 (3.53) | 4.92 (3.68) | 41.03 (3.52) | .01 |
| MCV, mean (SD), μm3 | 90.4 (4.64) | 90.8 (4.60) | 9.3 (4.64) | 90.1 (4.68) | <.001 |
| Homocysteine, mean (SD), mg/L | 1.70 (0.59) | 1.94 (0.71) | 1.67 (0.54) | 1.52 (0.48) | <.001 |
| TC, mean (SD), mg/dL | 209.27 (40.54) | 205.41 (38.61) | 209.27 (40.93) | 213.90 (40.93) | <.001 |
| HDL-C, mean (SD), mg/dL | 48.26 (11.97) | 47.10 (11.97) | 48.26 (11.97) | 49.42 (12.74) | <.001 |
| Triglycerides, median (IQR), mg/dL | 99.12 (71.68-142.48) | 97.35 (71.68-140.71) | 100.00 (71.68-143.36) | 98.23 (70.80-146.90) | .69 |
| TC/HDL-C ratio, median (IQR) | 4.38 (3.55-5.38) | 4.36 (3.60-5.39) | 4.40 (3.55-5.37) | 4.38 (3.51-5.37) | .70 |
| Glucose, mg/dL | 46.49 (79.28-95.50) | 84.68 (79.28-93.69) | 86.49 (81.08-95.50) | 86.49 (81.08-97.30) | <.001 |
| C-reactive protein, median (IQR), mg/L | 1.34 (0.61-3.04) | 1.18 (0.57-2.88) | 1.36 (0.63-3.03) | 1.47 (0.62-3.15) | .01 |
| eGFR, mean (SD), mL/min/1.73 m2 | 92.17 (17.10) | 92.12 (16.8) | 92.5 (17.1) | 91.5 (17.2) | <.001 |
| UAE, median (IQR), mg/24 h | 8.83 (6.09-16.25) | 8.45 (6.00-14.69) | 8.73 (6.08-15.90) | 9.38 (6.26-18.09) | <.001 |
| ALT, median (IQR), U/L | 17.0 (13.0-25.0) | 16.0 (12.0-22.0) | 18.0 (13.0-25.0) | 19.0 (14.0-28.0) | <.001 |
| AST, median (IQR), U/L | 22.0 (19.0-26.0) | 22.0 (19.0-25.0) | 22.0 (19.0-26.0) | 23.0 (20.0-28.0) | <.001 |
| ALP, mean (SD), U/L | 68.9 (20.3) | 67.28 (18.9) | 69.20 (2.5) | 70.26 (20.9) | <.001 |
| GGT, median (IQR), U/L | 24.0 (16.0-39.0) | 22.0 (15.0-35.0) | 24.0 (16.0-38.0) | 27.0 (17.0-46.0) | <.001 |
Abbreviations: ALP, alkaline phosphatase; ALT, alanine aminotransferase; AST, aspartate aminotransferase; BMI, body mass index (calculated as weight in kilograms divided by height in meters squared); BP, blood pressure; CKD, chronic kidney disease; CVD, cardiovascular disease; eGFR, estimated glomerular filtration rate; GGT, γ-glutamyltransferase; HDL-C, high-density lipoprotein cholesterol; IQR, interquartile range; MCV, mean corpuscular volume; TC, total cholesterol; UAE, urinary albumin excretion.
SI conversion factors: To convert plasma concentration of vitamin B12 to picomoles per liter, multiply by 0.7378; ferritin to picomoles per liter, multiply by 2.247; transferrin to micromoles per liter, multiply by 0.123; hemoglobin to grams per liter, multiply by 10; hematocrit to proportion of 1.0, multiply by 0.01; MCV to femtoliters, multiply by 1; homocysteine to micromoles per liter, multiply by 7.397; cholesterol to millimoles per liter, multiply by 0.0259; triglycerides to millimoles per liter, multiply by 0.0113; glucose to millimoles per liter, multiply by 0.0555; C-reactive protein to nanomoles per liter, multiply by 9.524; and ALT, AST, ALP, and GGT to microkatals per liter, multiply by 0.0167.
P values represent the significance of difference across the quartiles of plasmatic vitamin B12. P values were determined using a 1-way analysis of variance for normally distributed data, Kruskal-Wallis test for skewed distributed data, and χ2 test for categorical data.
Education levels were defined as low, no, primary, basic vocational, and secondary education; medium, senior secondary vocational and general senior secondary education; or high, higher professional and higher academic education.