Vitamin D and inflammation

Several studies found an inverse relationship between 25-hydroxyvitamin D [25(OH) D] and markers of inflammation. A controversy exists as to whether vitamin D lowers inflammation or whether inflammation lowers 25(OH) D concentrations. Certainly 25(OH) D concentrations fall after major surgery. However, is this due to inflammation lowering 25(OH) D or is 25(OH) D being metabolically cleared by the body to quell inflammation. We searched the literature and found 39 randomized controlled trials (RCT) of vitamin D and markers of inflammation. Seventeen found significantly reduced inflammatory markers, 19 did not, one was mixed and one showed adverse results. With few exceptions, studies in normal subjects, obesity, type 2 diabetics, and stable cardiovascular disease did not find significant beneficial effects. However, we found that 6 out of 7 RCTS of vitamin D3 in highly inflammatory conditions ( acute infantile congestive heart failure, multiple sclerosis, inflammatory bowel disease, cystic fibrosis, SLE, active TB and evolving myocardial infarction) found significant reductions. We found baseline and final 25(OH) D predicted RCTs with significant reduction in inflammatory markers. Vitamin D tends to modestly lower markers of inflammation in highly inflammatory conditions, when baseline 25(OH) D levels were low and when achieved 25(OH) D levels were higher. Future inquiries should: recruit subjects with low baseline 25(OH) D levels, subjects with elevated markers of inflammation, subjects with inflammatory conditions, achieve adequate final 25(OH) D levels, and use physiological doses of vitamin D. We attempted to identify all extant randomized controlled trials (RCTs) of vitamin D that used inflammatory markers as primary or secondary endpoints.