The Vitamin D Debate: Conundrums and Complexities

Recent Studies Investigating Vitamin D Supplementation for Nonskeletal Indications (cont.)

• A prospective analysis of data from a phase III study of 1,043 patients newly diagnosed with metastatic colorectal cancer found that patients with higher vitamin D levels had better outcomes after treatment with chemotherapy and targeted therapy. The median overall survival for patients with the highest vitamin D levels was 32.6 months, as compared with 24.5 months for those with the lowest levels.⁸
• Data from a cohort of 308,000 adults, aged 22–50 years old with at least one vitamin D measurement were analyzed for a possible association between vitamin D deficiency and asthma. The researchers found that among those with vitamin D deficiency , the odds of having an asthma exacerbation were 25% greater, compared to those with levels in the normal range – an association that remained significant, even after controlling for known confounders.⁹
• The potential protective effects of vitamin D against preterm birth were examined in 2,327 pregnant women who gave birth to singleton, liveborn neonates, vs. 1,126 women who delivered preterm babies. The researchers found that the incidence of preterm birth at <37 weeks of gestation significantly decreased as levels of 25-(OH)D increased to approximately 90nmol/L from lower rates. The researchers concluded, “Our data support a protective association between maternal vitamin D sufficiency and preterm birth.”¹⁰
• A Mendelian randomization analysis of 95,766 white participants of Danish descent from three cohorts, with median follow-up times of 19.1, 5.8, and 7.9 years were genotyped for genetic variants in DHCR7 and CYP2R1, affecting plasma 25-(OH)D concentrations. 35,334 also had plasma 25-(OH)D measurement. The researchers found that genetically low 25-(OH)D concentrations were associated with increased all-cause mortality, cancer mortality and other mortality, although not with increased cardiovascular mortality.¹¹