VITAMIN D & PAIN
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VITAMIN D & PAIN

Laurance Johnston, Ph.D.

Because we donít work outside like our agrarian ancestors and limit sun exposure due to warnings from dermatologists, we have become a vitamin-D-deficient society. Our skin may be less wrinkled, but below the surface there are health consequences. The bottom line is that we are much more likely to die from disorders aggravated by chronic underexposure to vitamin-D-producing sunlight than disorders aggravated by overexposure. Studies are showing that vitamin-D deficiency is associated with numerous health problems, such as osteoporosis, cancer, cardiovascular disease, mental-health problems, multiple sclerosis, and diabetes. 

Furthermore, because an efficient immune system requires ample vitamin D, virtually any disorder mediated through immune-system mechanisms will be adversely affected by the lack of this nutrient. One such disorder appears to be pain. Specifically, vitamin-D-deficient individuals tend to have more chronic pain, which seems to be alleviated by vitamin-D supplementation. Although understandings are still evolving, evidence indicates that vitamin D regulates the synthesis of key immune-system molecules (called cytokines) implicated in pain-associated inflammatory responses.

It is uncertain how much supplementation can lessen the unique pain experienced by individuals with spinal cord injury or dysfunction (SCI/D). For example, it may help in the shoulder pain associated with pushing a wheelchair or too many transfers but have little impact on neuropathic pain. Nevertheless, vitamin-D is a nothing-to-lose-potentially-much-to-gain approach that, at minimum, will enhance overall health.

Vitamin-D Deficiency

Vitamin-D levels can be measured through a simple blood test - even available through Internet self-test kits (e.g., http://www.zrtlab.com/vitamindcouncil/) or walk-in, lab-testing services popping up in many locations.  The test measures levels of a specific vitamin-D metabolite called 25-hydroxvitamin D which the body converts to biologically active vitamin D (see figure). Levels above 30 nanograms (one billionth of a gram) per milliliter are considered sufficient, between 20-29 ng/ml insufficient, and < 20 ng/ml inadequate.

Using these criteria, scientists estimate that one billion people worldwide lack health-optimizing vitamin-D levels. At special risk are the elderly and individuals with dark skin pigmentation, especially those who live in cloudy, northern latitudes. Wintertime sunlight possesses little of the wavelengths needed to produce vitamin D in much of the northern U.S.

In my case, moving from sunny Colorado to the overcast Pacific Northwest resulted in my vitamin-D levels plummeting to a health-affecting 15 ng/ml. When I relocated to sun-drenched New Mexico a few years later, levels increased to 50 ng/ml.  Overall, if you donít have sufficient sun exposure, closely monitor vitamin-D levels and take corrective actions as needed.

Scientists speculate that people with physical disability are more likely to have compromised vitamin-D levels because the disability limits time outside in the sun. One study indicated that individuals with chronic SCI were twice as likely to have deficient vitamin-D levels compared to able-bodied individuals. Levels apparently go down quickly after injury as demonstrated by another study showing deficient vitamin-D levels in 93% of patients admitted to acute, inpatient rehabilitation, including 21% who were considered severely deficient with levels <10 ng/ml.

Vitamin D & Pain

Numerous studies suggest that vitamin-D deficiency has a role in pain manifestation, including:

1) Dr. Vasant Hirani looked at the relationship of pain and vitamin-D levels in over 2,000 adults aged 65 and older living in England, a cloudy country whose capital London is further north than Winnipeg, Canada. Overall, as we age we become less efficient in synthesizing vitamin D and converting it to its physiologically active form. Hiraniís study indicated that moderate to extreme pain was present in 53% of these elderly individuals and was correlated with poor vitamin-D status.

2) Dr. Wei Huang and collaborators at the Atlanta VA Medical Center and nearby Emory University evaluated the effects of vitamin-D supplementation in 28 veterans with chronic pain and low vitamin-D levels. Age averaged 46 years, 18 were men, and 20 were African Americans (reflecting this groupís tendency to possess suboptimal vitamin-D levels). The average vitamin-D level was a deficient 18.6 ng/ml. After receiving vitamin-D supplementation for three months, levels increased to 26 ng/ml.

Subjects rated their pain before and after supplementation using a 0 to 10 pain scale, in which 0 corresponded to no pain and 10 as worst possible pain. In addition, a quality-of-life questionnaire was administered which asked about physical functioning, the extent health interferes with work, bodily pain, general health, vitality, social functioning, the degree emotional problems interfere with work, and mental health. Finally, another questionnaire was used to assess sleep quality, which is frequently affected by pain.

Using the 0-10 scale, average pain levels decreased from 7.1 to 5.7 after supplementation. Overall, subjects reported fewer areas of pain and a decreased use of pain medications. In addition, the results indicated an improvement in most of the quality-of-life components listed above, including the pain component. Finally, sleep improved after supplementation, e.g., subjects took less time to get to sleep and slept longer. The investigators concluded that ďvitamin-D supplementation in veterans with multiple areas of chronic pain can be effective in alleviating their pain and improving sleep, and various aspects of quality of life.Ē

3) Individuals with SCI often experience neuropathic pain due to neural-tissue damage. Although studies focused on using vitamin-D to lessen such pain are limited, Drs. Paul Lee and Roger Chen (Australia) examined vitamin-Dís potential to relieve pain in 51 vitamin-D-deficient diabetics. A common disorder in individuals with SCI, diabetes frequently causes pain-generating, peripheral nerve damage. Three months of supplementation increased vitamin-D levels in subjects from an average of 18 to 30 ng/ml. Several pain measures were assessed before and after supplementation, including a 0 (no pain) to 5 (excruciating pain) scale. Using this scale, pain levels decreased from 3.3 before supplementation to 1.7 afterwards, a 48% reduction.

Conclusion

Of the many therapies discussed in this Healing-Options series, few have the potential to enhance the overall wellness of individuals with SCI/D as much as vitamin D. In this era of costly, side-effect-laden medicine, vitamin D is an extraordinary simple way to augment health with a huge bang-for-the-buck impact - especially for people with SCI/D who are prone to vitamin-D deficiency and the manifold problems caused by this lack. Get more sun exposure, eat a vitamin-D-rich diet, or take a supplement, and youíll be healthier.

Adapted from article appearing in December 2012 Paraplegia News (For subscriptions, call 602-224-0500) or go to www.pn-magazine.com

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