Many people with diabetes suffer from a painful condition called peripheral neuropathy. The burning, numbness, tingling and throbbing sensations that primarily affect the feet are notoriously resistant to successful treatment. Two Australian research scientists have conducted a preliminary study showing that high doses of vitamin D may reduce these symptoms. It was published recently as a research letter in the Archives of Internal Medicine.
Drs. Paul Lee and Roger Chen found that low blood levels of vitamin D are “highly prevalent” in people with type 2 diabetes, and this was true for the 51 women and men who took part in their study. The participants, average age 62 years, were given high daily doses of vitamin D3 (cholecalciferol) in tablet form (mean dose, 2059 IU).
No Adverse Effects
The two research scientists defended the high doses used in their study by citing the ongoing debate among researchers over the optimal level of vitamin D. (See “More About Vitamin D” below.) Lee and Chen also described high doses of vitamin “free of adverse effects.”
Before and after the study, the 51 participants were asked to score the severity of their pain on a scale of one to five. 1) mild; 2) discomforting; 3) distressing; 4) horrible; and 5) excruciating. The participants on average ranked their pain as “distressing” at the start of the study. When the study ended at three months, their average pain score was between “mild” and “discomforting”. The results led Lee and Chen to hypothesize that “vitamin D supplementation may be an effective analgesic in relieving neuropathic pain.”
The two research scientists acknowledged the limitations of their study which did not randomly assign half the participants to receive a placebo. But they noted, “To our knowledge, this is the first prospective observational study addressing the impact of vitamin D repletion on neuropathic pain in patients with type 2 diabetes mellitus.”
Maryann Napoli, Center for Medical Consumers © May 2008
More about Vitamin D
The Recommended Daily Allowance for vitamin D is 400 IU for people age 50-70 years, 600 IU for people 70 years and older. Given the mounting evidence for this vitamin's role in preventing common cancers, autoimmune diseases, type 1 diabetes, heart disease, and osteoporosis, many of the country’s leading vitamin D researchers believe that the RDA is set far too low. One of them is endocrinologist Michael F. Holick, MD, PhD, of the Boston University School of Medicine.
When Dr. Holick was asked in 2004 whether an increase in the RDA for vitamin D was imminent, given the fact that the Institute of Medicine, a division of the National Academy of Science had recently held a meeting on that very topic. “No, it usually takes 10 to 15 years to change an RDA,” he answered. “A huge bureaucratic system is involved.” In the meantime, he and other vitamin D researchers recommend a minimum of 1000 IU vitamin D daily. This increase, he explained, will maximize the absorption of calcium.
The type of vitamin D is very important. “Multivitamins usually have D2 which comes from yeast, but it's probably only 20-40% as effective as D3,” which, Dr. Holick said is better and longer lasting. When asked about a risk of overdose, he explained, “You'd have to take 10,000 to 20,000 IU daily to approach toxicity.”
possible drug side effect until proved otherwise.”
Maryann Napoli, Center for Medical Consumers © May 2008
