Incremental Cholecalciferol Supplementation up to 15 μg/d Throughout Winter at 51–55° N Has No Effect on Biomarkers of Cardiovascular Risk in Healthy Young and Older Adults

Two separate, identical, double-blind, randomized, placebo-controlled intervention studies were carried out in the south and north of Ireland (51–558N). Men and women aged 20–40 y (n = 202) and $64 y (n = 192) received cholecalciferol at doses of 0 (P), 5 (D3–5), 10 (D3–10), or 15 (D3–15) mg/d (0–600 IU) during wintertime. Serum 25-hydroxyvitamin D [s25(OH)D], intact parathyroid hormone, systolic and diastolic blood pressure, fasting lipids, glucose and insulin, HOMA-IR, high-sensitivity CRP, matrix metalloproteinase-9, and its inhibitor (tissue inhibitor metalloproteinase-1) were measured at baseline (October) and 22 wk later at endpoint (March). Vitamin D receptor Fok Ia ndTaq I genotypes were analyzed and dietary intakes of vitamin D and calcium were assessed. In young adults, s25(OH)D decreased from baseline to endpoint (P , 0.001), except in the D3–15 group, who maintained the baseline concentration of ;70 nmol/L. Older adults had lower s25(OH)D at baseline (median, 54.2 nmol/L) and concentrations increased in the D3–10 and D3–15 groups (P , 0.001). There were no significant effects of supplementation on cardiovascular disease (CVD) risk biomarkers in either age group. Fasting glucose and total and HDL cholesterol were lower (P,0.05) in older adults with the Fok 1 ff genotype than in those with FF or Ff. Putative effects of vitamin D on cardio-metabolic health will only be evident at higher intakes than the current RDA and possibly in individuals at particular risk of low s25(OH)D and/or CVD risk. J. Nutr. 142: 1519–1525, 2012.