Various studies have proposed a connection between vitamin D and cardiovascular and metabolic disease, but this has not been validated in randomized, controlled trials. In a recent publication in the Journal of the American Heart Association, Miao et al conducted a prespecified, secondary analysis of the DAYLIGHT (Vitamin D Therapy in Individuals at High Risk of Hypertension) randomized, controlled trial.

The researchers conducted a meta-analysis of randomized, controlled trials reporting biomarker variations after vitamin D supplementation. In the analysis, they measured circulating homeostatic model assessment of insulin resistance, high-sensitivity C-reactive protein (hs-CRP), N-terminal pro-B-type natriuretic peptide, renin, aldosterone, and lipids at baseline and at 6 months in 289 subjects with low vitamin D status (25-hydroxyvitamin-D [25-OH-D] ≤25 ng/mL) receiving low-dose (400 IU/d) versus high-dose (4,000 IU/d) vitamin D3 for 6 months.

The researchers found that levels of 25-OH-D expanded in the high-dose vitamin D group relative to the low-dose vitamin D group (+15.5 vs. +4.6 ng/mL, P <.001). They also noted that changes in biomarkers of glycemia, inflammation, and neurohormonal activation did not vary by dose and that lipids did not differ between groups, other than triglycerides, which rose in the high-dose compared with the low-dose group (+11.3 vs. −6.2 mg/dL, P <.001).

The meta-analysis demonstrated potential modest reductions in homeostatic model assessment of insulin resistance and hs-CRP, but no changes in low-density lipoprotein, in the vitamin D–supplementation groups compared with control groups. The researchers concluded that, in the DAYLIGHT trial, high-dose vitamin D supplementation did not improve biomarkers of glycemia, inflammation, neurohormonal activation, or lipids.

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