A group of researchers from the Institute of Neuroscience in Sweden have recently found that vitamin D may help with muscle fatigue in patients with myasthenia gravis.
Myasthenia gravis is an autoimmune disorder that affects the neuromuscular system. Fatigue is the greatest characteristic of the disease. Patients with myasthenia gravis experience muscle weakness in their eyes, face, limbs, and respiratory system. The first signs of the disease are droopy eyelids, difficultly making facial expressions, difficulty chewing food and even slurred speech. The prevalence of myasthenia gravis in the United States is 20 cases per 100,000 people. Treatment includes medications and/or surgery.
In this study, the investigators wanted to know, what is the prevalence of vitamin D deficiency in myasthenia gravis and could vitamin D supplementation improve fatigue?
They recruited 33 myasthenia gravis patients from an outpatient neurology clinic between late 2010 through early 2012. Twenty-two were male with an average age of 59 and eleven of the participants were female with an average age of 57. Seventeen of the patients already supplemented with vitamin D (800 IU/day) and calcium, while sixteen did not supplement.
They measured vitamin D levels at baseline and administered “the myasthenia gravis composite scale” that scores myasthenia gravis from 0 (no myasthenia weakness) to 50 (worst possible myasthenia weakness in all muscles). At baseline, they found:
- In the group who did not supplement, the average myasthenia gravis composite scale score was 4.5 (0 to 13 range). Their average vitamin D level was 20.4 ng/ml.
- In patients who already supplemented with vitamin D, the average myasthenia gravis composite scale score was 5.5 (0 to 19 range). Their average level vitamin D level was 31.6 ng/ml.
Next, the researchers supplemented the group that had not supplemented before with 800 IU/day. They mildly rose vitamin D levels from 20.4 ng/ml to 24.6 ng/ml after 2.5-10 month follow up. They also administered the myasthenia gravis composite scale in the follow-up session. They found:
- Scale scores dropped from 4.5 to 2.5.
- The overall improvement in the scores was 38% (p=.05).
The results show that vitamin D may help muscle fatigue in patients with myasthenia gravis. The authors postulate that the improvement may have been from improved T cell function.
Study weaknesses include the small number of participants and a lack of a placebo arm to compare to. A strength of the study, however, was that the clinicians who administered the scale score were not aware of the participants’ previous scores. Expectedly, the investigators call for a larger randomized controlled trial.
One cannot help but wonder what kind of response the patients would have had if a more physiologic dose had been administered and vitamin D levels had been raised above 30 or 40 ng/ml. The Vitamin D Council recommends 5,000 IU/day in persons without contraindications to vitamin D, and there are no known contraindications between vitamin D and myasthenia gravis.