High-dose vitamin D fails to improve cardiometabolic biomarkers
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High-dose vitamin D supplementation did not have beneficial effects on biomarkers of glycemia, inflammation, neurohormonal activation or lipid status, according to new data from the DAYLIGHT trial.
In a secondary analysis of the DAYLIGHT trial of vitamin D supplementation in 289 individuals at high risk for hypertension, researchers found that those assigned high-dose vitamin D supplementation did not have improvements in biomarkers of insulin resistance, inflammation, neurohormonal activation or lipids compared with those assigned low-dose supplementation.
The high-dose group received 4,000 IU per day for 6 months compared with 400 IU per day for 6 months for the low-dose group.
According to the researchers, demographic and clinical features were comparable between the low-dose and high-dose vitamin D groups, but baseline values of plasma triglycerides were slightly lower in the high-dose group (P = .03).
At 6 months, 25-hydroxyvitamin D concentrations rose to a greater degree in the high-dose supplementation group compared with the low-dose group (15.5 ng/mL increase vs. 4.6 ng/mL increase; P < .001), the researchers wrote.
The researchers found that fluctuations in high-sensitivity C-reactive protein, glucose, insulin, the homeostatic model assessment of insulin resistance (HOMA-IR), N-terminal pro-B-type natriuretic peptide, renin, aldosterone, total cholesterol, HDL and LDL did not differ between the treatment arms.
Plasma triglycerides increased in the high-dose group compared with the low-dose group at 6 months (11.3 mg/dL vs. –6.2 mg/ dL; P < .001), according to the researchers.
The researchers also conducted a meta-analysis of 23 vitamin D supplementation trials including DAYLIGHT. In that analysis, there was no difference between the treatment and control groups in LDL, but compared with the control groups, the vitamin D supplementation groups had modest decreases in HOMA-IR (mean difference, –0.53; 95% CI, –0.6 to –0.46) and hsCRP (mean difference, –0.58; 95% CI, –1 to –0.15), according to the researchers.