Vitamin B12 and Multiple Sclerosis

A vitamin B12 deficiency can cause neurological symptoms that mimic those of multiple sclerosis (MS). Symptoms of both conditions include muscle weakness, difficulty walking, cognitive dysfunction, and sensory disturbances.

Vitamin B12, clinically known as cobalamin or, sometimes, cyanocobalamin, is a water-soluble micronutrient that, among other things, is important to the normal function of the nervous system. Because of this role, it's been hypothesized that in some cases a deficiency of vitamin B12 may be linked to MS, although this theory is controversial.

Researchers are looking into whether there is a definitive link between B12 deficiency and multiple sclerosis. Regardless of these findings, low levels of B12 are associated with symptoms and health issues, so it's important to understand how it supports the brain and spinal cord. It's also a good reason to make sure you're getting enough of the vitamin in your diet.

This article discusses how vitamin B12 can affect your nervous system and whether it can help manage MS. It also covers the symptoms of vitamin B12 deficiency and what can cause it.

Vitamin B12 Deficiency and MS
Verywell / Hilary Allison

Vitamin B12 Deficiency and the Nervous System

Vitamin B12 plays a key role in helping to maintain myelin—the sheath, or layer, of protein and fatty material that surrounds nerves, including those in the brain and spinal cord. It's the myelin sheath around individual nerve cells that insulates them and makes it possible for electrical signals to be transmitted quickly and efficiently.

It's easy to see, then, why a deficiency of B12 can cause MS-like symptoms such as:

  • Muscle weakness
  • Difficulty walking
  • Cognitive dysfunction
  • Sensory disturbances like Lhermitte's sign

Despite this similarity, though, vitamin B12 deficiency and multiple sclerosis differ in significant ways.

B12 Deficiency
  • Affects central and peripheral nervous systems

  • Early symptoms (numbness, tingling) that may progress to muscle weakness and gait unsteadiness

  • More likely affects legs rather than arms

  • Affects both sides of the body equally

  • More common in middle-age or elderly individuals

  • Can be diagnosed with simple blood test

  • On an MRI, the brain or spinal cord appear normal

  • May cause other problems, such as anemia and glossitis (in which the tongue becomes swollen and painful)

Multiple Sclerosis
  • Affects only the central nervous system

  • Early symptoms manifest and progress in a variety of ways that are unpredictable

  • Doesn't impair one body part more than another

  • May be more predominant on the left or the right side of the body

  • More common in people in their 20s or 30s

  • Difficult to diagnose; requires multiple exams and tests

  • In most cases, an MRI will show lesions on brain or spinal cord

  • Not associated with any co-existing conditions

Even though vitamin B12 deficiency and multiple sclerosis are different conditions, they can co-exist. In fact, there has been research to suggest that people with MS are more likely to have a deficiency of B12 than are those who are otherwise healthy.


Myelin Sheath and the Role It Plays in MS

Can B12 Help Manage MS?

This doesn't mean, however, that there's a link between B12 deficiency and multiple sclerosis. In fact, in a 2020 meta-analysis published in International Journal of Medical Sciences, researchers were not able to find such a connection.

However, some research has found evidence that supplementation of vitamin B12, often along with another B vitamin, folate (B9), may help to alleviate some symptoms of the disease.

In a 2019 study published in Clinical Nutrition Research, for example, researchers looked at how B12 and folate supplements might affect quality of life for a group of participants with relapsing-remitting multiple sclerosis (RRMS), a form of the disease in which periods of normal health are punctuated by relapses of symptoms.

The scientists first tested the blood of each subject to find out if any had significant deficiencies (no one did). The participants were then divided into two groups: One group received a 5-milligram (mg) tablet of folic acid and three 1,000-micrograms (mcg) doses of B12 by injection each day. The other subjects got a daily placebo tablet and shot.

After two months, blood samples were taken from all participants; each person also completed a questionnaire designed to measure quality of life in people living with MS.

The members of the supplementation group were found to have lower levels of an amino acid called homocysteine that normally is broken down by vitamins B12, B6, and folic acid. (When levels of homocysteine are high, it may be a sign of a vitamin deficiency.)

More importantly, the supplement group had an improvement in both physical and mental quality of life. (The placebo group also had significant improvement in mental quality of life.)

By no means does this study (and a few others with similar findings) prove taking B12 will help with the management of MS. However, it clearly is an indication that more research is needed.

Causes of Vitamin B12 Deficiency

Vitamin B12 is found in dairy products, eggs, meat, chicken, shellfish, and fortified foods. People who are vegan or who follow a very strict vegetarian diet can be at risk of developing a B12 deficiency simply because they don't consume enough natural food sources of the vitamin.

Other reasons for vitamin B12 deficiency include:

  • Taking certain medications known to affect vitamin B12 levels. Common examples include the diabetes medication metformin and medications used to treat heartburn known as proton pump inhibitors.
  • Conditions that interfere with the absorption of nutrients, such as celiac disease and Crohn's disease
  • Bariatric surgery (such as gastric sleeve surgery) for weight loss, which has been found to affect how nutrients are absorbed
  • Pernicious anemia, a condition in which a person cannot properly absorb vitamin B12 from foods because they lack intrinsic factor, a protein produced in the stomach

Diagnosis of B12 Deficiency

If you have symptoms that suggest you may have a deficiency of B12, your healthcare provider can confirm this suspicion simply by checking the levels of the vitamin in a sample of your blood.

If your vitamin B12 levels are on the low side of normal, your healthcare provider may order two more blood tests: homocysteine and methylmalonic acid. These metabolic substances are both elevated in vitamin B12 deficiency.

Although this is the most typical way to diagnose B12 deficiency, other tests may be used, including magnetic resonance imaging (MRI) of the spinal cord (to look for a bright signal in the posterior part of the cord), or somatosensory or visual evoked potentials.

Treating B12 Deficiency

Since B12 is readily available in common foods, dietary changes may be enough to bring blood levels up to normal. A simple approach to turning around a deficiency would be to eat more B12-rich foods, such as clams, beef liver, certain varieties of fish, and fortified nutritional yeast or cereals.

The recommended dietary allowance of vitamin B12 for teens and adults 14 and up is 2.4 mcg. Women who are pregnant are advised to get 2.6 mcg of B12 each day, and those who are breastfeeding are advised to get even more—2.8 mcg.

Someone who is found to be deficient in B12 may need to take oral supplements of the vitamin or receive it via intramuscular injections. It can take some time, and in many cases, lifelong supplementation, to bring blood levels of vitamin B12 to normal and keep them there.

A Word From Verywell

The jury is still out about the association between vitamin B12 deficiency and multiple sclerosis, as well as whether B12 supplements can help alleviate MS symptoms. What cannot be disputed, however, is that eating a well-balanced diet that includes ample vitamin B12 is a smart move for anyone who's dealing with any chronic health problem or who's healthy overall and wants to do everything possible to stay that way. And whichever category you fall into, if you develop symptoms that suggest either MS or a B12 deficiency, see your healthcare provider. Having your levels checked is easy.

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Multiple Sclerosis Trust. Vitamin B12.

  2. Nemazannikova N, Mikkelsen K, Stojanovska L, Blatch GL, Apostolopoulos V. Is there a link between vitamin B and multiple sclerosisMedicinal Chemistry. 2018;14(2):170-180. doi:10.2174/1573406413666170906123857

  3. Miller A, Korem M, Almog R, Galboiz Y. Vitamin B12, demyelination, remyelination and repair in multiple sclerosis. J Neurol Sci. 2005;233(1-2):93-7. doi:10.1016/j.jns.2005.03.009

  4. Li X, Yuan J, Han J, Hu W. Serum levels of homocysteine, vitamin B12 and folate in patients with multiple sclerosis: an updated meta-analysisInt J Med Sci. 2020;17(6):751-761. doi:10.7150/ijms.42058

  5. Nozari E, Ghavamzadeh S, Razazian N. The effect of vitamin B12 and folic acid supplementation on serum homocysteine, anemia status and quality of life of patients with multiple sclerosis. Clin Nutr Res. 2019;8(1):36-45. doi:10.7762/cnr.2019.8.1.36

  6. National Institutes of Health, Office of Dietary Supplements. Vitamin B12 fact sheet for health professionals.

Additional Reading

By Julie Stachowiak, PhD
Julie Stachowiak, PhD, is the author of the Multiple Sclerosis Manifesto, the winner of the 2009 ForeWord Book of the Year Award, Health Category.