In 33 patients undergoing knee arthroplasty, plasma 25-hydroxyvitamin D (25[OH]D) levels were measured preoperatively, 6 to 12 hours after surgery, then daily for 5 days, and then after 3 months. By day 2 postoperatively, there was a large increase in the median C-reactive protein (CRP) concentration and a 42.5% decrease in the median 25(OH)D concentration (p < 0.001). At day 5 and at 3 months, median 25(OH)D levels were still 27.5% and 19%, below the preoperative values, respectively (p < 0.001 and p = 0.003, respectively).
Comment: Low serum 25(OH)D levels are associated with a number of different diseases, many of which have an inflammatory component. However, it is not clear whether these low levels are an effect or a cause of inflammation. The concentrations of various nutrients (including other lipid-soluble vitamins) decrease in response to inflammation, and in the context of an inflammatory response, the circulating levels of these nutrients are generally unreliable as indicators of nutritional status. The results of the present study suggest that the same may be true with respect to vitamin D. For people with chronic diseases that have an inflammatory component, one might reasonably question whether serum 25(OH)D is a reliable indicator of vitamin D nutritional status. As a corollary, observational studies that link inflammatory diseases to low 25(OH)D levels do not necessarily imply that vitamin D supplementation would prevent or ameliorate those diseases. More controlled trials Df vitamin D supplementation are needed.
(As far as I know, Garden Of Life is the only company that make a RAW Vitamin D)
11 November 2011