Vitamin B6: Too Much of a Good Thing?

Neuropathy in multiple sclerosis (MS) causes pain and paresthesias, or abnormal sensations. Many if not most of us have experienced some form of neuropathic pain due to damage to nerve fibers in our brains or spinal cords (also known as the central nervous system, or CNS).

Peripheral neuropathy is damage to the nerves outside the CNS. The peripheral nerves carry messages from the central nervous system to our extremities (hands, arms, legs, and feet), and from our extremities to the CNS.

Interestingly, the symptomatic experience of peripheral neuropathy can be almost identical to the neuropathy caused by MS.

An Avoidable Cause of Peripheral Neuropathy

While the medical community has known for decades that high doses of vitamin B6 can cause peripheral neuropathy, the general public appears less aware. A recent case series described eight people with peripheral neuropathy due to taking high doses of over-the-counter (OTC) vitamin B6, sometimes as part of a multivitamin. Some had decided on their own to take it; in other cases, a healthcare professional had recommended it.

So common are reports of peripheral neuropathy linked to vitamin B6 that regulators in Australia tightened regulations on the sale and use of B6 (also known as pyridoxine).

Vitamin B6 Supplementation Useful in MS?

A recent study looked at the role of vitamin B6 in multiple sclerosis. Researchers analyzed B vitamin concentrations in the blood of 99 participants before and after three weeks of endurance exercise.

They found that lower blood levels of B6 were associated with higher expanded disability status scale scores, indicating more disability.

However, after endurance exercise, the participants with greater disability showed an increase in levels of vitamin B6 as well as B2 (riboflavin).

The authors of the study state, “It should further be investigated whether B vitamin supplementation may offer therapeutic benefits in counteracting progressing disease mechanisms in different stages of MS.”

Caution Is Needed

Even with possibility that supplementation with B vitamins has benefits for people with MS, caution is still needed.

In the United States, the daily upper limit of vitamin B6 from all sources (food, beverages, supplements) is 100 milligrams (mg) for adults age 19 and older.

But in 2023, the European Food Safety Authority halved the tolerable daily intake of vitamin B6 from 25 mg per day to 12 mg per day for all adults because of the risk of peripheral neuropathy.

These differing recommendations are examples of why so many people with chronic illnesses are both baffled and frustrated. But they — along with studies showing the potential downsides of supplements — serve as a potent reminder to tell our medical professionals about all the medications and supplements (prescription, OTC, and naturopathic) we take.

We may think we’re doing something positive to fight our disease, but we could be doing the opposite.

Wishing you and your family the best of health.

Cheers,

Trevis