Renegade Neurologist

From wsj.com
Peripheral neuropathy, or damage to nerves in hands and feet, can cause tingling, pain and numbness. A high-dose vitamin B supplement to treat neuropathy can alleviate pain and improve sensation, says a company that sells it. A few scientific studies show improvement in symptoms, but many physicians remain skeptical.

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Neuropathy can result from chemotherapy medications, traumatic injuries and infections, but the most common cause is diabetes. Nearly 30% of diabetics who are at least 40 years old have impaired sensation in the feet, according to the American Diabetes Association. In the long run, the numbness can result in undetected wounds being neglected to the point where the foot must be amputated.

There is no cure, physicians say, though diabetics can minimize the problem by keeping blood sugars under control. Ibuprofen is sometimes used to reduce the pain, as are anti-depressants or anti-convulsants. However none of these treatments improves sensation in the feet.

Metanx, a high-dose vitamin supplement available only by prescription, has been shown in unpublished clinical trials to improve foot sensation and pain, according to Pamlab LLC, a Covington, La., company that sells it. Metanx works by helping to boost the production of nitric oxide, which opens blood vessels and improves blood flow to peripheral nerves, the company says.

Metanx contains a form of folate that is more accessible to the body than many over-the-counter supplements, plus high doses of vitamins B-6 and B-12, Pamlab says. Side effects can include nausea and skin rashes, but both are generally temporary, the company says. Taking Metanx costs $40 to $70 a month, depending on the dose.

Vitamin B supplements for neuropathy have yielded mixed results. In a July review by the Cochrane Collaboration, a nonprofit scientific group, researchers reviewed 13 studies and found “insufficient” evidence for vitamin B use to treat neuropathy.

Pamlab says those studies involved lower and less bioavailable doses than Metanx. A 97-patient study by St. Louis podiatrist Mark Allen Jacobs, presented last month at a scientific conference, found a reduction in neuropathic pain of 35% in patients who took Metanx for 20 weeks, compared with 12% for those taking acetaminophen, the active ingredient in Tylenol. That study wasn’t fully “blinded” in that the patients knew which pills they were taking.

“At this point, the evidence is certainly interesting,” says Christopher Gibbons, director of the Periperal Neuropathy Clinic at the Joslin Diabetes Center in Boston. “It would be terrific if it were true — we just don’t know yet.” He adds that those who were helped may have been deficient in vitamin B.