Introduction Some observational studies have associated low vitamin D status with increased cardiovascular disease (CVD) and risk factors in adults, but results from randomised controlled trials suggest these associations may not be causal. Trials have largely used supplementation with vitamin D2 and the availability of D3 supplements has led to the suggestion that this is more potent and null effects in previous trials may be because of inadequate dosage of vitamin D.
Methods We conducted a cross-sectional study of 4274 children from the Avon Longitudinal Study of Parents and Children (ALSPAC), comparing associations of serum 25-hydroxyvitamin D2 (25(OH)D2) and 25-hydroxyvitamin D3 (25(OH)D3 with several CVD risk factors: systolic and diastolic blood pressure (SBP; DBP), lipids (triglycerides, LDL-c, HDL-c, Apo-A1 and Apo-B) adiponectin, leptin, CRP and IL6.
Results In fully adjusted models including age, sex, ethnicity, socioeconomic position, waist circumference and mutual adjustment, 25(OH)3 was positively associated with HDL-c (change per doubling of 25(OH)D3: 0.02 mmol/l; 95% CI 0.0 to 0.04) and Apo-A1 (2.7 mg/dl; 1.5, 3.8), and inversely associated with IL6 (−7.8%; −12.3, −3.1). Equivalent analyses for 25(OH)D2 found positive associations with CRP (8.0%; 3.2, 13.0) and IL6 (5.0%; 1.5, 8.7). Neither exposure was associated with any other outcome. There was statistical evidence that associations of D2 and D3 differed for triglycerides, Apo-A1, adiponectin, CRP and IL6 (all p values for heterogeneity <0.04).
Conclusions 25(OH)D2 and 25(OH)D3 differ in their associations with CVD risk factors, but with no clear evidence in children that D3 is necessarily a more potent risk factor for CVD risk.