Research & Your Health is a series of articles written in accessible, everyday language, focused on the latest scientific research of natural health products.
On April 20, 2015
Background: Inflammation can be a key component of the onset and progression of many chronic conditions such as depression, cardiovascular disease, autoimmune diseases and cancer. There has been debate within the scientific literature around the role that vitamin D may play in lowering or raising levels of inflammation.
Objective: This study explored past research to analyze if vitamin D has an effect on inflammation and whether low levels could be a cause of inflammation or if inflammation causes lower levels of vitamin D.
Methods: Randomized controlled trial studies of vitamin D and inflammatory markers that had been published up until July 2014 were compiled. Of the 60 found, 39 were included in the narrative review.
Results: Nineteen studies found no effect; 19 found a beneficial effect; one found a mixed effect; and one found a negative effect of vitamin D on inflammatory markers. The 19 studies that found vitamin D to have a benefit were conducted with populations who had pre-existing, highly inflammatory conditions. Those studies which showed limited benefit were conducted with participants who suffered from mild inflammatory conditions. The greatest results were seen in the groups that had the lowest levels of inflammation at baseline.
Conclusion: When markers of inflammation were elevated at baseline, vitamin D may have helped to reduce these markers. This suggests that vitamin D aids in decreasing inflammation rather than low vitamin D levels being the result of inflammation. Findings in Perspective: The findings from this study indicate that the impact of vitamin D on inflammatory markers will depend on the disease state and baseline levels of inflammation. These results suggest that the effect of vitamin D in healthy populations may not be as strong in lowering inflammatory markers as in populations where the disease state is marked with modest to high levels of inflammation. As vitamin D has a role in many other biological functions, the findings of this analysis should not prevent individuals who do not have a condition marked with inflammation from supplementing with vitamin D. Vitamin D supplementation is found to be free from side effects when used in appropriate doses. Click here to read the complete scientific abstract.