Research published last week in the journal Nutrients suggests that patients with autoimmune diseases who are also vitamin D deficient have a significantly higher risk of disease activity, compared to those with higher vitamin D levels.
Researchers in Canada were interested in studying vitamin D status and disease activity of people with systemic autoimmune rheumatic disorders. Autoimmune diseases are a group of disorders where your immune system malfunctions and attacks your body’s own tissues. Autoimmune diseases can either attack a particular organ (organ specific) or attack numerous organs (systemic). An example or a systemic autoimmune disease is systemic lupus erythematosis (SLE) where the immune system attacks any organ in the body.
Systemic autoimmune rheumatic disorders (SARDs) are a group of systemic autoimmune disorders that include: Rheumatoid arthritis, lupus, Sjögren’s syndrome, systemic sclerosis, dermatomyositis and more. Rheumatoid arthritis is the most common of the group affecting 0.9% of the Canadian population, with prevalence expected to rise to 1.3% over the next 30 years. The chronic nature of the disorder ensures over 50% of patients will be disabled within the first 10 years of disease if not managed correctly.
Dr Zohreh Sabbagh, MD, of the Department of Internal Medicine at the University of Saskatchewan in Canada and colleagues collected data on 116 patients in a community clinic. The study population consisted of a case group: 60 patients with autoimmune disease, and a control group: 56 patients with non-autoimmune conditions.
Participants in the control group suffered mainly from osteoarthritis, osteoporosis, fibromyalgia and gout. In the case group, rheumatoid arthritis (RA) was the most common condition. Information on age, sex, BMI, vitamin D status, supplement use, and disease activity was collected. Here’s what the researchers found:
- Although a majority of the participants in the case (92%) and control (84%) groups reported supplementing with 1,000 IU vitamin D daily, the mean vitamin D status of those in the autoimmune disease group was significantly lower than those in the control group (p<0.05). Twenty patients (35%) in the case group and 11 patients in the control group (20%) were vitamin D deficient (< 20 ng/ml).
- Vitamin D deficiency was associated with increased CRP in patients in the autoimmune disease group (case group). CRP is a marker of inflammation.
- Among participants with rheumatoid arthritis in the case group, the odds of having active disease was 5.15 times higher in patients with low vitamin D levels compared to those with sufficient levels (p=0.03).
“Our study is the first Canadian study to evaluate the vitamin D status of rheumatology outpatients in two distinct groups: those who are suffering from SARD in comparison to non-SARD patients. We found significantly low plasma 25(OH)D in SARD group compared to non-SARD group despite similar self-reported vitamin D supplement use, as well as seasonal difference in plasma 25(OH)D concentration in SARD cases,” the authors explain.
Higher risk of disease activity for RA patients with low vitamin D is consistent with past research that suggests problems with vitamin D metabolism in RA, as well as a link between low vitamin D status and disease activity in rheumatic disorders. Interestingly, the authors report that only 3% of the study population was evaluated for vitamin D status.
The between group differences in vitamin D status, despite similar supplementation guidelines, suggests a need for “different requirements for this specific clinical population who are suffering from SARD.”
Remember, we cannot conclude that the increased disease activity is directly due to vitamin D deficiency because of observational nature of the study. The authors recommend further large scale, multi-center interventional studies to assess the full effect of vitamin D supplementation on people with rheumatoid arthritis as well as other SARDs.
Sabbagh Z, Markland J, Vatanparast H. Vitamin D status is associated with disease activity among rheumatology outpatients. Nutrients, 2013.
Systemic Rheumatic Disease. Immuno Concepts. 2011.