Chronic Pain Stymied by B Vitamins

SAN DIEGO--Certain B vitamins may have application in reducing chronic pain, as suggested by animal research presented at Experimental Biology 2003, held here April 11 to 15. Xue-Jun Song, M.D., Ph.D., and Zheng-Bei Wang, M.D., of the Parker Research Institute in Dallas, presented findings that indicated vitamins B1, B6 and B12, as well as a combination of the three, produced short- and long-term inhibition of chronic pain caused by nervous system damage.

Chronic pain affects approximately 86 million Americans per year, according to the American Physiological Society (www.the-aps.org), which hosts the Experimental Biology conferences. However, hope may exist in the form of certain B vitamins, which have been shown to alleviate pain caused by conditions such as lumbago, sciatica, trigeminal neuralgia, facial paralysis and optic neuritis. Nociceptive pain, caused by any number of factors such as sprains, fractures or bruises, originates nerves called nociceptors. When they sense damage in any part of the body, they become activated and respond by signaling the brain, although B vitamins may have an anti-nociceptive effect.

To test this theory, Song and Wang investigated whether B vitamins could have an anti-nociceptive effect in animals with neuropathic pain that was the result of an injury or malfunction in the peripheral or central nervous system. Researchers implanted stainless steel rods in the spines of adult, male rats to stimulate CCD (chronic compression of dorsal root ganglion), an animal model of painful human sequelae (a morbid condition that develops after primary sensory neuron injury has occurred from disease). After the rats were induced to CCD, researchers investigated several treatments to reduce pain, as measured by foot withdrawal latency to heat stimulation.

Rats were treated with either intrathecal (i.t.) injection or intraperitoneal (i.p.) injection of one of several treatments, including saline, vitamin B1, vitamin B6, vitamin B12 and a B complex. Results indicated vitamins B1, B6, B12 and their combination, both through i.p. and i.t. injection, significantly inhibited thermal pain, demonstrated by reversal of the shortened latency of foot withdrawal to heat stimulation. The inhibition occurred in a dose-dependent manner. Additionally, pain was inhibited about 20 percent to 100 percent at two, six and 12 hours, and recovered at 24- or 36-hour tests, depending on dosage.

Researchers concluded spinal application and i.p. injection of B vitamins reduced both severity and duration of CCD pain. They also stated their results "strongly support" the use of B vitamins in clinical settings to reduce chronic pain or other diseases caused by injuries to the nervous system.