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Table 4 Serum 25(OH)D in relation to calcium and vitamin D intakes in all subjects and gender specific in 1917 subjects in the sub-study

From: Increased calcium intake is associated lower serum 25-hydroxyvitamin D levels in subjects with adequate vitamin D intake: a population-based observational study

  Calcium intake§ < 500 mg/d Calcium intake§ 500–999 mg/d Calcium intake§ 1000–1499 mg/d Calcium intake§ > 1499 mg/d
n Serum 25(OH)D (nmol/L) n Serum 25(OH)D (nmol/L) n Serum 25(OH)D (nmol/L) n Serum 25(OH)D (nmol/L)
All subjects‡
 Vitamin D intake (ug/d)§
   < 7.0 86 59.4 (55.4, 63.5) 230 60.4 (57.9, 62.9) 125 63.8 (60.2, 67.4) 53 69.3 (62.2, 76.4)##*
  7.0–13.9 44 61.7 (55.3, 68.1) 225 66.2 (63.4, 69.1) 236 66.2 (63.6, 68.8) 119 65.3 (62.0, 68.6)
  14.0–20.9 15 81.6 (70.3, 92.8) 85 75.1 (69.9, 80.2) 130 71.2 (67.7, 74.7) 104 67.8 (64.1, 71.4)#*
   > 20.9 16 81.1 (68.0, 94.2)† 143 74.5 (71.3, 77.6)† 151 76.6 (73.5, 79.8)† 155 75.4 (72.4, 78.5)†
 Males‡
 Vitamin D intake (ug/d)§
   < 7.0 28 58.7 (51.2, 65.5) 92 59.4 (55.7, 63.1) 44 57.8 (53.1, 62.6) 19 54.6 (45.9, 63.2)
  7.0–13.9 21 56.6 (46.6, 66.6) 103 63.3 (59.4, 67.1) 107 63.8 (60.0, 67.6) 66 61.8 (57.4, 66.2)
  14.0–20.9 4 76.6 (50.1, 103.0) 33 74.4 (64.2, 84.6) 56 67.1 (62.4, 71.8) 50 61.6 (56.3, 66.9)#*
   > 20.9 4 81.8 (35.2, 128.5) 68 75.7 (70.6, 80.8)† 62 75.2 (70.9, 79.4)† 71 71.0 (67.3, 74.7)†
Females‡
 Vitamin D intake (ug/d)§
   < 7.0 58 59.8 (54.6, 64.9) 138 61.1 (57.8, 64.4) 81 67.1 (62.2, 71.9) 34 77.5 (68.5, 86.6)##**
  7.0–13.9 23 66.3 (58.0, 74.7) 122 68.7 (64.6, 72.8) 129 68.2 (64.7, 71.7) 53 69.7 (64.7, 74.7)
  14.0–20.9 11 83.4 (68.7, 98.1) 52 75.5 (69.7, 81.2) 74 74.3 (69.3, 79.3) 54 73.4 (68.7, 78.2)
   > 20.9 12 80.9 (65.4, 96.3)† 75 73.3 (69.4, 77.3)† 89 77.7 (73.2, 82.2)† 84 79.2 (74.6, 83.7)
  1. #P < 0.05, ## < 0.01. Linear trend for serum 25(OH)D across calcium D intake groups without adjustments
  2. *P < 0.05, **P < 0.01. Linear trend for serum 25(OH)D across calcium intake groups with sex, age, BMI and month of blood sampling (using dummy variables) as covariates
  3. P < 0.001. Linear trend for serum 25(OH)D across vitamin D intake groups without adjustments as well as with sex, age, BMI and month of blood sampling (using dummy variables) as covariates
  4. ‡ Subjects in the Tromsø study with valid food frequency questionnaires, serum 25(OH)D measurement, not been on a sunny vacation last 2 months, not taking solarium regularly, with valid serum PTH measurement, and with serum calcium < 2.51 mmol/L
  5. § Including supplements
  6. The data are mean (95% CI). The P values are adjusted for multiple testing with a factor of 4