Vitamin B12 is an essential nutrient for good health. Some of the best sources of vitamin B12 include meat, fish, eggs, fortified foods, and supplements. It may also be advisable to limit or avoid alcohol.

Vitamin B12 is a water-soluble vitamin that is important for proper red blood cell formation, neurological function, and DNA synthesis.

A vitamin B12 deficiency can lead to anemia, as well as neurological and psychiatric symptoms.

People who may be at risk of vitamin B12 deficiency include older adults, people following a vegan diet, and individuals with increased vitamin B12 requirements due to specific health conditions.

Animal products, such as meat, fish, and eggs, contain vitamin B12 in varying amounts. The following is a list of good sources:

Clams are a good source of vitamin B12Share on Pinterest
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  • clams
  • liver
  • oysters
  • salmon
  • canned tuna
  • beef
  • low fat yogurt
  • low fat milk
  • turkey breast
  • eggs

A person should consume these foods in moderation as part of a healthful diet.

The above food sources are all unsuitable for people following an entirely plant-based diet.

Learn more about vitamin B12 deficiencies.

Vitamin B12 is not present in plant foods, so people on a plant-based diet need to obtain it through fortified foods and supplements.

Foods that are sometimes fortified and may contain vitamin B12 in varying amounts include:

  • breakfast cereals
  • nutritional yeast
  • soya drinks

It is important to read the nutritional information on a fortified product to ensure that it contains vitamin B12.

Someone following a vegan diet might consider B12 supplements.

Some foods and drinks can interfere with vitamin B12 intake:

Folic acid-fortified foods

Folate (vitamin B9) is an essential nutrient, especially before and during pregnancy. The Centers for Disease Control and Prevention (CDC) states that people of reproductive age need 400 micrograms (mcg) of folic acid (synthetic folate) each day.

However, too much folic acid can mask a vitamin B12 deficiency. Research suggests that high folate levels can even exacerbate anemia and cognitive symptoms associated with a lack of vitamin B12. Still, the idea that high folate levels cause low levels of B12 is still controversial among scientists.

Generally, adults with good overall health should not exceed 1,000 mcg of folic acid daily from fortified foods.

Alcohol

Research has suggested that excessive consumption of alcohol may reduce vitamin B12 levels. Specifically, B12 deficiency can affect 25% of people who misuse alcohol.

Alcohol-related liver disease can also falsely increase vitamin B12 test levels, according to an older 2010 study.

People with alcohol use disorder may need supplements to correct vitamin B12 deficiency and anemia.

Foods with insufficient vitamin B12

Some people believe that certain plant-based foods are good sources of vitamin B12. These foods include:

However, many researchers believe that these foods are not adequate to correct a deficiency of vitamin B12. For instance, the vitamin B12 in cyanobacteria, such as spirulina, has very low bioavailability.

Therefore, although people can include the above foods as part of a healthful diet, they should not rely on them as a source of vitamin B12.

The recommended daily allowance (RDA) for vitamin B12 varies according to a person’s age and whether they are pregnant or breastfeeding.

The following table shows the RDA for vitamin B12:

AgeIntake
14 years and over2.4 mcg
9–13 years1.8 mcg
4–8 years1.2 mcg
1–3 years0.9 mcg
7–12 months0.5 mcg
0–6 months0.4 mcg
During pregnancy2.6 mcg
While breastfeeding2.8 mcg

There is no known risk of having too much vitamin B12.

Learn more about high vitamin B12 intake.

Vitamin B12 supplements are available in the form of tablets or liquids that a person can take under the tongue (sublingually).

Who needs them?

People eating a plant-based diet may need additional vitamin B12 in the form of supplements, especially when pregnant or breastfeeding.

Additionally, older adults, people with gastrointestinal conditions, and those on certain medications, including proton pump inhibitors and metformin, may need to take a supplement.

Dosage

The absorption of vitamin B12 is about 2% at doses of 500 mcg or 1.3% at a dose of 1,000 mcg. Therefore, if someone consumes vitamin B12 less frequently, they will need a higher total amount to achieve a sufficient absorbed quantity. To maximize absorption, people should chew the tablets or allow them to dissolve in the mouth.

Researchers report that in vegetarians or vegans with marginal B12 deficiency, a dose of 50 mcg daily or 2,000 mcg weekly could be beneficial.

Severe deficiency

If a person has a severe vitamin B12 deficiency, a doctor may advise them to have injections to increase their levels of this nutrient.

Learn more about vitamin B12 injections.

Vitamin B12 is an essential nutrient, and deficiency can lead to severe complications and ill health.

People who eat a varied diet and are generally in good health can obtain the required amount of food. However, older adults, those on certain medications or with gastrointestinal issues, and people who follow a plant-based diet may be more at risk of deficiency. These people can take a supplement or speak to their doctor, who may recommend vitamin B12 injections.

Those on a vegan or mostly plant-based diet should be wary of information sources advising that foods such as seaweeds deliver adequate amounts of vitamin B12. Research suggests that this is incorrect and that those on a plant-based diet should include fortified foods and supplements.

A person should speak to their doctor if they have any concerns about nutritional supplements.