A combination of B vitamins has been found to reduce the severity of chronic pain in rats. The new research suggests that relief from chronic pain, which affects millions every year, could be provided in the form of vitamin tablets.
B-vitamins, such as thiamin (B1), pyridoxine (B6), and cyanocobalamin (B12), have previously been shown to offer pain relief in conditions such as lumbago, sciatica, facial paralysis and optic neuritis.
Researchers Dr Xue-Jun Song and Dr Zheng-Bei Wang, both from the Parker Research Institute in Dallas, US, highlighted evidence suggesting that the vitamins could help treat nociceptive pain, which comes from sprains, bone fractures, burns, bumps and bruises. Here the pain originates from the nociceptors, nerves which sense and respond to parts of the body which suffer from damage.
However with researchers recently developing an animal model to simulate chronic pain, through chronic compression of the dorsal root ganglion (DRG), the Dallas team sought to test the efficacy of B-vitamins in animals with neuropathic pain, a result of an injury or malfunction in the peripheral or central nervous system.
They presented their findings at the American Physiological Society conference in San Diego from April 11-15, 2003.Experiments were performed on adult, male Sprague-Dawley rats weighing 200-250g with neuropathic pain caused by primary sensory neuron injury. The researchers surgically implanted stainless steel rods into the intervertebral foramen. Postoperative tests were conducted 1, 3, 5, 7, 10, 14 days after surgery and then once weekly for up to 10 weeks in some rats to examine the long-term effects of B vitamins.
For examining short-term effects, tests were conducted for up to 14 days and additional tests 2, 6, 12, 24 and 36 hours after injection of B vitamins on the third day after surgery.
The vitamins B1, B6, B12 and their combination significantly inhibited pain in the rats, from 20-100 per cent at two, six and 12 hours, depending on different doses. The extreme sensitivity to stimuli disappeared four to five weeks after injury in rats with combined B vitamin treatment. In contrast, pain lasted for eight to ten weeks in rats with saline or without any treatment. The researchers add that they found that combination of threshold doses of individual vitamins produced a synergetic inhibitory effect on pain sensibility.
Dr Song concluded that both severity and duration of hyperalgesia are reduced by a combination of B vitamins. "These results strongly support clinical use of B-vitamins in aiding in treatment of chronic pain and/or other diseases due to similar injuries to the nervous system," write the researchers.