What you need to know about neuropathy and the B vitamins – Medical Rehabilitation Specialists

Neuropathy and the B Vitamins

By Katharine Leppard, MD, Medical Rehabilitation Specialists, Colorado Springs LIVING WELL Magazine

Peripheral neuropathy is a dysfunction of the nerves, typically affecting the feet first, that can cause a variety of symptoms including numbness, pain and balance problems. This condition affects 20 million Americans, yet many people have never heard of it. Vitamin B supplementation is often recommended to treat neuropathy and, often, the thought, “If a little is good, then even more is better,” has been applied to the B vitamins. However, there are some critical pieces of information about the B vitamins that are important to know.

Peripheral neuropathy symptoms can vary widely, and can include pain, numbness, burning, stinging, uncomfortable tingling, shooting sensations, weakness or balance difficulties. Typically these symptoms affect the longest nerves first, the nerves in our feet, followed by the nerves in our hands. Nerve pain can be especially severe at night, and often does not respond to standard pain medications such as anti inflammatory and narcotic medications. It is hard to understand how a numb foot can also feel severe pain.  One way to look at a peripheral neuropathy is that it is a “short circuit” of the nerves.   The injured nerves cannot feel the normal sensations that we want to feel, causing numbness in the feet and sometimes balance difficulties. Yet those same injured nerves may register a normally non-painful stimulus, something as simple as a sheet touching a foot, as painful. I have had patients tell me they feel as if they are walking on river rocks or sand. Others report they feel as if there is tape or leather on the bottom of the feet. The “bunched sock” sensation is classic for neuropathy, patients feel as if there is a sock bunched under the foot, when the sock is perfectly fine, or even when there are no socks on the feet. Other patients notice balance problems as the first symptom, and have no pain, and because the onset of numbness was so gradual, don’t even notice numbness.

There are many causes and types of peripheral neuropathies. The most common cause in the U.S. is diabetes. Other known causes include thyroid disease, vitamin B12 deficiencies, hereditary forms, alcohol abuse, renal disease, toxins such as heavy metals, and damage from medications including some forms of chemotherapy. Over 30% of peripheral neuropathies have no identifiable cause and are called idiopathic neuropathies.  Idiopathic neuropathies can be very frustrating and hard to understand when diagnosed in an otherwise healthy person.

Peripheral neuropathy is diagnosed by EMG, a specialized test that measures how well the nerves carry an electric stimulus, and looks for abnormality in the electrical activity in the muscle. Small fiber neuropathies affect the microscopic nerves in the skin, in this case the EMG is normal, and a skin biopsy can be done for diagnosis. Once a diagnosis of peripheral neuropathy is made, there are lab tests that need to be done to look for treatable causes of peripheral neuropathy. These labs include tests for diabetes, thyroid dysfunction, Vitamin B12 level, folate and a specialized protein test called a serum protein electrophoresis.

Vitamin B12 deficiency is common. It is estimated that 10-25% of people over the age of 80 have a B12 deficiency. B12 deficiencies can cause anemia, optic nerve issues, spinal cord degeneration and peripheral neuropathy. Vitamin B12 is found in red meat, dairy, fish and eggs. The recommended daily dose varies depending on the resource. The Mayo Clinic recommends a 1,000-2,000-mcg oral dose, or 500-mcg sublingual daily dose for B12 deficiency. The tricky thing about B12 is that it requires a chemical made by the stomach called the intrinsic factor to be absorbed by the body. As we age, the production of this intrinsic factor can drop off. Many people have excellent diets or take B12 supplements, and they simply are not absorbing the B12. The only way to check Vitamin B12 is a blood test that measures the B12 level. Normal levels average 200-900 pg/ml, however there are many studies that report that neurologic symptoms can develop with B12 blood levels less than 400 pg/ml.  If people do not absorb B12 normally, they need to do B12 injections.

Vitamin B6 can actually be toxic to nerves in doses above 100 mg/day. Vitamin B6 is included in prescription medications such as Metanx, and in many health supplement drinks, protein powders and tablets. You need to add how much Vitamin B6 is in your daily supplements. I have had patients who took megavitamins and health supplements in an attempt to be healthy, developed foot numbness, come to the office for evaluation and are diagnosed with peripheral neuropathy. They are shocked to learn they have actually been doing harm with excess Vitamin B6.

Once nerve damage has occurred, the medical treatment options are limited. If no underlying condition is found to treat, it is a symptom management situation. There are medications to help with neuropathic pain such as Lyrica, Cymbalta and Neurontin, but these medications do not improve nerve function or reverse nerve damage.

Peripheral neuropathy can lead to significant suffering and even disability in severe cases. The risk of falls, which can be catastrophic, increases fourfold in senior citizens with peripheral neuropathy. Small foot wounds can lead to major infections in a numb foot. Proper diagnosis and blood tests are important. The take home lessons with the B vitamins:

  1. The goal of the blood test for Vitamin B12 is to be greater than 400, shots may be needed.
  2. Keep the Vitamin B6 supplement oral dose less than 100 mg per day.

Dr. Leppard is with Medical Rehabilitation Specialists and may be reached at 719-575-1800.