Recently, headlines around the world reported that vitamin D does not work.
- Vitamin D Shows No Benefit Against Cancer, Heart Disease
- Report questions effectiveness of vitamin D supplements
- Vitamin D Shows No Benefit in Fighting Cancer, Heart Disease
- Serum 25(OH)D Marker of Ill Health, Not Causative Agent
The cause of all these articles was a Lancet paper by Autier et al, which we blogged on.
Basically, the Autier et al paper concluded that inflammation caused vitamin D levels to go down, not the other way around. What Autier did not specifically highlight was the randomized controlled trials showing vitamin D reduces markers of inflammation when markers of inflammation are elevated.
- Arnson, Y. et al. Vitamin D inflammatory cytokines and coronary events: a comprehensive review. Clin Rev Allergy Immunol, 2013.
- Abou-Raya A, Abou-Raya S, Helmii M. The effect of vitamin D supplementation on inflammatory and hemostatic markers and disease activity in patients with systemic lupus erythematosus: a randomized placebo-controlled trial. J Rheumatol, 2013.
- Coussens, A. K. et al. Vitamin D accelerates resolution of inflammatory responses during tuberculosis treatment. Proc Natl Acad Sci USA, 2012.
- Grossmann, R. E. et al. Impact of vitamin D supplementation on markers of inflammation in adults with cystic fibrosis hospitalized for a pulmonary exacerbation. Euro J of Clin Nutr, 2012.
- Neyestani, T. R. et al. Improvement of vitamin D status via daily intake of fortified yogurt drink either with or without extra calcium ameliorates systemic inflammatory biomarkers, including adipokines, in the subjects with type 2 diabetes. J Clin Endocrinol Metab, 2012.
- Shab-Bidar, S. et al. Improvement of vitamin D status resulted in amelioration of biomarkers of systemic inflammation in the subjects with type 2 diabetes. Diabetes Metab Res Rev, 2012.
- Hopkins, M. H. et al. Effects of supplemental vitamin D and calcium on biomarkers of inflammation in colorectal adenoma patients: a randomized, controlled clinical trial. Cancer Prevention Research, 2011.
- Zittermann, A. et al. Vitamin D supplementation enhances the beneficial effects of weight loss on cardiovascular disease risk markers. Am J Clin Nutr, 2009.
Recently, a review on the subject by senior author Professor Bess Dawson-Hughes got no press attention.
Her thesis in the paper is simple. For randomized controlled trials to show an effect against markers of inflammation, two conditions must be present:
- Low baseline vitamin D levels
- Elevated markers of inflammation
The eight studies above meet these criteria, and that is why they were successful trials. But not all trials are successful, because they don’t always meet the above criteria. As she points out, in the largest cross-sectional study, NHANES, markers of inflammation like hs-CRP are only associated with 25(OH)D levels when those levels are less than 21 ng/ml.
The authors concluded:
“Apparent inconsistencies across recent studies of vitamin D status and inflammation may result primarily from differences between the populations being studied. Improving vitamin D status may be of most benefit when starting levels of 25OHD are low, when starting markers of inflammation are high, or in both scenarios. Future interventions should be targeted to populations with these characteristics, notably those who are older, obese, sedentary, and with chronic conditions involving inflammation. While this might seem obvious, there is currently a remarkable lack of information about vitamin D and inflammation in these groups.“