A research letter published in the April 14, 2008 issue of the American Medical Association journal Archives of Internal Medicine reported that vitamin D supplementation reduced pain levels in patients with diabetic neuropathy. The condition occurs when high levels of glucose damage the nerves, and can include burning, tingling, numbness, and throbbing sensations.
Drs Paul Lee and Roger Chen of the Concord Repatriation General Hospital in New South Wales, Australia enrolled 51 type 2 diabetics with neuropathy for the study. Pain severity was rated via two questionnaires and serum 25 hydroxyvitamin D and parathyroid hormone levels were measured at the beginning and end of the treatment period. All participants were found to have insufficient levels of vitamin D at less than 24 nanograms per cubic milliliter at the study's onset, and were given a mean dose of 2,059 IU of the vitamin for three months.
Lower pain scores were found to be correlated with higher levels of serum vitamin D but not with parathyroid hormone levels. Treatment with vitamin D resulted in a 48.5 percent reduction in pain scores on the first questionnaire and a 39.4 percent reduction on the second by the end of three months.
Drs Lee and Chen remark that there is evidence that vitamin D promotes nerve growth and modulates neuromuscular function and neuronal growth and differentiation. Having inadequate levels of the vitamin could increase nerve damage and impair pain receptor function. They note that vitamin D supplements are unlikely to have harmful effects and may also benefit bone health and glycemic control in diabetic patients.
To the authors' knowledge, the study is the first of its kind to address the effect of vitamin D on patients with diabetic neuropathic pain. 'Vitamin D insufficiency is underrecognized and may be a significant contributor to neuropathic pain in type 2 diabetes,' they conclude. 'Vitamin D supplementation may be an effective ‘analgesic' in relieving neuropathic pain.'Related Health Concern: Neuropathy
In all forms of neuropathy, there is abnormal stimulation of nerves or damage that results in pain. Peripheral nerves are sensitive conduits that carry impulses from the extremities back to the central nervous system (i.e., the spinal cord and brain). Impulses are transmitted along nerves by changes in the electrical charge of the cell membrane caused by movement of ions such as sodium, potassium, and calcium. Impulses are transmitted between nerves by neurotransmitters such as acetylcholine and substance P, which is responsible for transmitting pain impulses. For protection, most nerves are covered with a thin sheath called myelin, which is made from choline and lipids. The myelin functions like the rubber wrapping around an electrical cord: it insulates the nerve fibers and prevents abnormal transmissions.
Depending on the nature of the specific neuropathy, some part of this system breaks down. In diabetic neuropathy, for example, there is a change in the microvascular network that supplies the nerve with nutrients. This lack of blood supply and nutrients causes the nerve to function abnormally. Diabetic neuropathy tends to occur in more than one nerve area (this condition is called polyneuropathy) and may cause loss of sensation and pain that typically worsens at night. In severe cases, diabetics can suffer from a kind of neuropathy called autonomic neuropathy. In this case, the autonomic nervous system, which controls automatic body functions, is affected with possibly serious consequences, including gastrointestinal problems, bladder-emptying problems, abnormal heart rhythms, and even sudden death (El-Atat FA et al 2004).
The following supplements have been shown to reduce the pain associated with neuropathy:
- Fat-soluble vitamin B1 (benfotiamine) - 150 milligrams (mg) one to three times daily
- Acetyl-L-carnitine - 2000mg daily
- R-lipoic acid - 300 to 450mg daily (or alpha-lipoic acid: 600 to 1000 mg daily)
- NAC - 600mg daily
- Curcumin - 800 to 1600mg daily
- Gamma linolenic acid (GLA) - 900 to 2700mg daily
- EPA/DHA - 4000 mg daily, providing at least 1400mg EPA and 1000mg DHA
- Vitamin B6 - 100mg daily
- Vitamin B12 - 1000 micrograms (mcg) of the methylcobalamin form, taken one to four times daily (up to 40mg daily methylcobalamin may be used in extreme cases)
- Vitamin C - about 2500mg daily
- Vitamin E - 400 international units (IU) daily (with around 200mg gamma tocopherol)