Doctors may recommend vitamin B12 supplements for those with certain health conditions or dietary restrictions. The dosage can vary based on factors including age, sex, and medical history.

Vitamin B12 is a water-soluble nutrient that’s required for many crucial processes in your body, such as maintaining healthy blood.

The ideal dose of vitamin B12 varies based on your sex, age, and reasons for taking it.

Learn more about the uses of vitamin B12 supplements and the evidence behind the recommended dosages for different people.

Vitamin B12 is an essential nutrient that plays a critical role in several of your body’s processes.

It’s necessaryTrusted Source for proper red blood cell production, DNA formation, and nerve function.

Vitamin B12 also plays a key role in reducing levels of an amino acid called homocysteine, high levels of which have been linked to chronic conditions like heart disease, stroke, and Alzheimer’s.

Additionally, vitamin B12 is important for energy production. However, there’s currently no evidence that taking B12 supplements increases energy levels in people who are not deficient in this nutrient.

Vitamin B12 is found mostly in animal products, including meats, seafood, dairy products, and eggs. It’s also added to some processed foods, such as cereal and nondairy milk.

Because your body can store B12 for several years, serious B12 deficiency is rare.

It can be caused by not getting enough of this vitamin through your diet, problems with absorbing it, or taking a medication that interferes with its absorption.

If you’re at risk of deficiency, taking a supplement may help you meet your needs.

The recommended dietary allowance (RDA) for vitamin B12 for people over 14Trusted Source is 2.4 micrograms (mcg).

However, you may need to take more or less, depending on your age, lifestyle, and specific situation.

Note that the percent of vitamin B12 your body can absorb from supplements is not very high — it’s estimated that your body only absorbs 10 mcg of a 500-mcg B12 supplement.

Here are some recommendations for B12 dosages for specific circumstances.

Adults under age 50

For people over 14, the RDA for vitamin B12 is 2.4 mcg.

Most people meet this requirement through diet.

For example, if you ate the following you would consume more than double your daily B12 needs:

  • two eggs for breakfast (1 mcgTrusted Source of B12)
  • 85 grams (g) of tuna for lunch (2.5 mcg of B12)
  • 85 g of beef for dinner (2.4 mcg of B12)

Therefore, supplementing with B12 is not recommended for healthy people in this age group.

However, if you have any of the factors described above that interfere with vitamin B12 intake or absorption, you may want to consider taking a supplement.

Adults over age 50

Older adults are more prone to vitamin B12 deficiency.

As you age, your body naturally makes less stomach acid and intrinsic factor.

Stomach acid is necessary to access the vitamin B12 found naturally in food, and intrinsic factor is required for its absorption.

Due to this increased risk of low absorption, it is recommended that adults over the age of 50Trusted Source meet most of their vitamin B12 needs through supplements and fortified foods.

Pregnant people

Pregnant people have slightly higher vitamin B12 needs than the general population.

Low maternal levels of this vitamin have been associated withTrusted Source birth defects in infants.

Therefore, the Recommended Dietary Allowance (RDA) for vitamin B12 during pregnancy is 2.6 mcg. This level can be met through diet alone or with a prenatal vitamin.

Breastfeeding people

Vitamin B12 deficiency in nursing infants has been linked to developmental delay.

Additionally, B12 deficiency in infants can lead to lethargy, decreased appetite, and failure to thrive.

For these reasons, the RDA for this vitamin for people who are breastfeeding is higher than that for those who are pregnant — namely 2.8 mcg.

Vegetarians and vegans

Vitamin B12 recommendations do not differ for people following a plant-based diet.

However, the RDA of 2.4 mcg for people under 50 years of age is much harder to meet on a vegetarian or vegan diet.

There are currently no government recommendations for B12 supplement dosages for vegetarians.

However, a healthcare professional can help you come up with a tailored diet plan to meet your nutritional needs.

Vitamin B12 is a water-soluble vitamin, meaning that your body excretes what you don’t need in your urine.

Because it’s relatively safe, no tolerable upper intake level (UL)Trusted Source has been set for vitamin B12. UL is considered the maximum amount of a substance that can be taken safely without side effects.

However, vitamin B12 has been shown to cause rare side effects in some cases.

Vitamin B12 injections may lead to skin changes, such as acne and dermatitis (rash).

People with kidney disease should also avoid high doses of B vitamins unless recommended by a doctor.

Importance of Vitamin B12 and How to Recognize a Deficiency
In this video, a registered dietitian covers everything you need to know about Vitamin B12.
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Vitamin B12 is a nutrient that plays many essential roles in your body.

The RDA for vitamin B12 ranges from 2.4 mcg for adults to 2.8 mcg for breastfeeding or chest feeding people.

Most people meet these needs through diet alone, but older adults, people on strict plant-based diets, and those with digestive disorders may benefit from supplements, though dosages vary based on individual needs.