A lack of methylcobalamin can cause severe damage to the body, including irreversible neurological harm.

Methylcobalamin is a form of vitamin B12, the most complex vitamin. Traditionally, vitamin B12 supplements and fortified foods have used cyanocobalamin or hydroxocobalamin. But the human body cannot use these substances directly in metabolism. First, it has to transform them into an active form, like methylcobalamin. That’s why some vitamin B12 supplements now use methylcobalamin.

Most people that eat a balanced diet get enough vitamin B12 from their food. But this doesn’t mean the body is able to use all of it. Some medical conditions prevent B12 absorption and cause vitamin deficiency. That’s because methylcobalamin is a chemical compound that the microorganisms in your gut produce. People who have a gut disease may not be able to absorb B12 from food or supplements. Also, older people, as well as those who take some forms of medication, may be at risk of vitamin B12 deficiency.

Let’s find out more about the role of this essential nutrient in the body, the symptoms and causes of methylcobalamin deficiency, and how to get B12 from food and supplements.

What Is Methylcobalamin?

Methylcobalamin is a type of vitamin B12. A vitamin is an organic substance the body needs in a tiny amount in order to function well. Vitamins are essential nutrients that the body cannot make on its own. So, you need to get vitamins from food and supplements. If you lack a vitamin or can’t absorb it because of a disease, you may become vitamin deficient. Vitamin deficiency can cause disease.

Methylcobalamin is a water-soluble vitamin. The body absorbs these vitamins easily and doesn’t store too much of them. The other type of vitamins are fat soluble, and the body can store them for use as needed.

Vitamin B12 is the most complex vitamin in terms of chemical structure. It differs from all other vitamins because it has a metal ion, cobalt, in its structure. This is why its forms are called cobalamins.

Methylcobalamin is one of the two active forms of vitamin B12, along with 5-deoxyadenosylcobalamin. Many B12 supplements and fortified foods use cyanocobalamin. But the cells cannot use this form of vitamin B12. They need to convert it to an active form of vitamin B12 first.

The Role of Methylcobalamin in the Body

Vitamin B12 plays a key role in the functioning of the brain and nerves, as well as in the formation of red blood cells. In addition, the body uses vitamin B12 in energy production and regulation, among other metabolic roles. Metabolism comprises all the processes through which the body assimilates a substance or eliminates one.

Here are the main roles of methylcobalamin in the body:

• Methylcobalamin protects neurons and regenerates damaged nerves. Doctors have used it in the treatment of some diseases, such as Alzheimer’s and rheumatoid arthritis.
• The body also needs vitamin B12 to preserve the integrity of the fatty cover that protects neurons (myelin sheath). Scientists need to do more work to prove whether vitamin B12 deficiency contributes to increasing the risk of dementia — a disease that damages neurons — in older people.
• Methylcobalamin works together with folate in the synthesis of DNA. A deficiency of methylcobalamin or folate hurts the production of red blood cells.
• Studies have found people with depression have low levels of vitamin B12, though it’s not clear whether vitamin B12 can cause depression.
• Research studies have shown there is a connection between osteoporosis and vitamin B12 deficiency. So, you need vitamin B12, as well as folate, for bone health. These two nutrients are also essential to protect yourself from cardiovascular disease. Also, they play a key role in preserving DNA integrity.
• Some studies have found evidence of a connection between low levels of vitamin B12 and increased risk of breast cancer.
• Some researchers suggest that methylcobalamin in combination with other substances could ease back pain, neck pain and trigeminal neuralgia. But researchers don’t understand the mechanisms of B12 as a painkiller yet.

Symptoms of Methylcobalamin Deficiency

If your body doesn’t get enough vitamin B12, or if it can’t absorb it properly, you may start having symptoms of vitamin B12 deficiency. The main symptoms are neurological and gastrointestinal.

The neurological symptoms of vitamin B12 deficiency include

• numbness,
• difficulty walking,
• disorientation,
• tingling of the feet and hands,
• problem concentrating, and
• memory loss.

These symptoms appear and progress gradually. The bad news is that once these symptoms become severe, vitamin B12 supplements cannot reverse neurological damage. So, you need to prevent vitamin B12 deficiency to protect your nervous system.

Some of the gastrointestinal symptoms of vitamin B12 deficiency are

• loss of appetite,
• diarrhea or constipation, and
• tongue soreness.

In addition, vitamin B12 deficiency might lead to chronic stomach inflammation. Finally, if the body doesn’t properly absorb vitamin B12 from the diet (meaning you ingest enough of it, but the body can’t turn it into a usable form), you can get megaloblastic anemia.

Causes of Methylcobalamin Deficiency

The body needs very little vitamin B12 a day. So, most healthy adults who eat a balanced diet that includes animal-derived foods get plenty of vitamin B12 from their diet.

Though most Americans get enough vitamin B12 from food, vitamin B12 deficiency affects up to 15 percent of the population, according to the National Institutes of Health.

B12 Malabsorption

The main cause of vitamin B12 deficiency is intestinal malabsorption. Older adults and those with certain diseases can’t absorb vitamin B12 from food. Even if they get enough vitamin B12 from their diet, the body can’t extract or use the form of vitamin B12 it needs.

You can suffer from intestinal malabsorption if your stomach, small intestine or pancreas doesn’t function normally. Also, if you regularly take antacids, you may be at risk of vitamin B12 deficiency. This is because the body uses stomach acid to separate vitamin B12 from food, but antacids prevent it.

Other Diseases

Several other medical conditions can lead to vitamin B12 deficiency. Two chronic inflammatory diseases of the stomach are among the leading causes of vitamin B12 deficiency: pernicious anemia and food-bound vitamin B12 malabsorption.

Pernicious anemia is an autoimmune condition that happens when your own antibodies attack your stomach cells.

People who have food-bound vitamin B12 malabsorption cannot properly absorb B12 from food, and usually have atrophic gastritis. As their body cannot use the B12 from food, they need vitamin B12 in the crystalline form that fortified foods and dietary supplements provide.

Another cause of methylcobalamin deficiency is a stomach disease called atrophic gastritis. This disease affects an estimated 30 percent of people over 60 years of age. Since the stomach doesn’t function well, bacteria can overgrow in the small intestine and block the proper absorption of vitamin B12 from food or supplements.

Other medical conditions can cause or contribute to vitamin B12 deficiency. These include

• celiac disease,
• Crohn’s disease,
• pancreatic insufficiency,
• chronic alcoholism,
• AIDS, and
• Imerslund-Grasbeck syndrome (a rare inherited disease).

Vegan or Vegetarian Diet

Finally, a strict vegetarian or vegan diet can put you at risk of vitamin B12 deficiency. That’s because in general only animal-derived foods naturally contain vitamin B12.

Recent studies have revealed that some fermented vegetables, edible algae and mushrooms have vitamin B12. But the amount of vitamin B12 in vegetables is not enough to meet your daily needs.

So, if you have a strict vegan diet, you should eat B12 fortified foods as well as getting supplements to minimize the risk of vitamin B12 deficiency.

Vitamin B12 Recommended Dietary Allowance (RDA)

As mentioned before, people need a small daily amount of vitamin B12.

The Food and Nutrition Board decides the recommended dietary allowance (RDA) for each vitamin. The RDA is how much vitamin B12 the majority of healthy people should consume to meet their nutrient requirements.

• The RDA for vitamin B12 is 2.4 micrograms per day for healthy adolescents (14–18 years) and adults aged 18–50 years.
• Infants and children need less than that amount, between 0.9 and 1.8 micrograms per day, depending on age. Check with your pediatrician to ensure your child gets the right amount of vitamins.
• Pregnant women need 2.6 micrograms of vitamin B12 a day.
• Finally, adults older than 50 need to get vitamin B12 supplements or B12 fortified foods, because they have a higher risk of food-bound malabsorption.

What happens if you exceed the RDA of vitamin B12?

Theoretically, nothing if you are a healthy adult. Getting more than the RDA of vitamin B12 a day shouldn’t be bad for you. This may be because when you ingest a high dose of vitamin B12, your body absorbs only part of it. If you are pregnant or have a medical condition, please check with your doctor.

The Food and Nutrition Board hasn’t established an upper intake limit for B12, due to lack of data. This doesn’t mean you should exaggerate, though.

How to Get Methylcobalamin, or Vitamin B12

Sources of vitamin B12 include food and supplements.

Foods That Have Vitamin B12

Generally, vegetables don’t have methylcobalamin. To get vitamin B12, you need to eat animal sourced foods or take supplements.

According to the FDA, some of the foods that contain vitamin B12 are

• dairy,
• eggs,
• fortified cereals,
• meats,
• poultry, and
• seafood (for example, clams, trout, salmon, haddock and tuna).

Vitamin B12-rich foods include the following, according to the Linus Pauling Institute at the University of Oregon.

• Clams: 84.1 micrograms per serving (3 ounces)
• Mackerel: 16.1 micrograms per serving (3 ounces)
• Skimmed milk: 0.9 micrograms serving (8 ounces)
• Eggs: 0.4 micrograms per egg (poached)
• Chicken: 0.4 micrograms per serving (3 ounces)

To find out how much B12 vitamin is in other foods, search the USDA Food Composition Databases.

Methylcobalamin Supplements

Many oral B12 supplements contain cyanocobalamin, a form of vitamin B12 that the body cannot use directly. But some B12 supplements contain methylcobalamin, a form of vitamin B12 your body needs.

If you eat a balanced diet and take supplements that have methylcobalamin, you may get more vitamin B12 than the RDA. But high levels of vitamin B12 are generally safe, if you are a healthy adult, as mentioned above. A 2011 study found no toxic effects (hypervitaminosis) even when people ingested as much as 10 mg of vitamin B12 a day — that’s about 4,000 times more than the RDA.

Summary and Conclusion

Methylcobalamin is a form of vitamin B12. This is an essential nutrient for your body to function properly and fight disease. There are several forms of vitamin B12, called cobalamins. The form that many B12 supplements use is cyanocobalamin. But the body cannot use cyanocobalamin directly. It has to transform it into activated forms, like methylcobalamin, which is the most effective for use by the cells.

According to the FDA, vitamin B12 plays a key role in the conversion of food into energy, the functioning of the nervous systems and red blood cell formation. In older people, vitamin B12 deficiency may contribute to stroke and neurodegenerative disorders (such as Alzheimer’s, Parkinson’s, multiple sclerosis and dementia).

Most Americans get enough vitamin B12 from their diet, as the body needs very little vitamin B12 a day. Still, between 1.5 and 15 percent of the population of the United States is vitamin B12 deficient, according to the National Institutes of Health.

To keep your digestive and nervous systems — and your entire body — functioning well, you need to make sure your body absorbs enough vitamin B12.

The people most at risk of vitamin B12 deficiency are those with certain digestive diseases, older people, and those with a strict vegan or vegetarian diet. If you take medication, speak to your doctor about vitamin B12 intake. Certain drugs (like antacids, some medicines for high cholesterol and some drugs for gout) reduce the absorption of vitamin B12.

If your diet lacks B12-rich foods, or if you need a higher dose of vitamin B12 than you can get from food, methylcobalamin is available as supplements.