ZURICH—Blood levels of vitamin D increased and were more sustained by oral supplementation with 25(OH)D(3) than they were with vitamin D3 supplementation, as were improvements to lower extremity function, according to new research from University Hospital Zurich; both forms improved several markers of innate immune function. The results were published online ahead of print Oct. 25 in the Journal of Bone and Mineral Research.
Twenty healthy postmenopausal women with an average 25(OH)D level of 13.2 ng/ml (SD = ± 3.9) and a mean age of 61.5 years (SD = ± 7.2) were randomized to receive either 20 µg of 25(OH)D(3), also known as calcidiol, or 20 µg (800 IU) of vitamin D(3) per day in a double-blind design. During 14 visits over the course of four months, researchers measured 25(OH)D serum levels, blood pressure, and 7 markers of innate immunity (eotaxin, IL-8, IL-12, IP-10, MCP-1, MIP-1β, RANTES). They also tested for lower extremity function (knee extensor and flexor strength, timed up and go, repeated sit-to-stand) at baseline and at four months, adjusting for baseline measurement, age and body mass index (BMI) in all analyses.
In the calcidiol group, mean 25(OH)D levels increased to 69.5 ng/ml, and the rise was more immediate and sustained compared to the D3 group, which showed a slow increase to 31.0 ng/ml. The calcidiol group also had a 2.8-fold increased odds of maintained or improved lower extremity function (OR= 2.79; 95%CI: 1.18-6.58), compared to the D3 group, and a 5.7 mmHg decrease in systolic blood pressure. Both types of vitamin D were linked to a decrease in 5 out of 7 markers of innate immunity, although decreases for eotaxin, IL-12, MCP-1 and MIP-1 β were significantly more pronounced with calcidiol. The researchers noted there were no cases of hypercalcemia at any time point in the study.
