Vitamin B12 is an essential water-soluble vitamin. The body doesn't make vitamin B12, so it must be obtained through food. It can be found in meat, seafood, and dairy products. It is also added to certain foods like breakfast cereal.
Vitamin B12 contains the trace element cobalt, which is why it is sometimes mentioned as cobalamin, cyanocobalamin, hydroxycobalamin, methylcobalamin, or 5-deoxyadenosylcobalamin.
If you cannot get enough vitamin B12 through diet, you may need to take it in supplement form. Vitamin B12 supplements can help treat or prevent a deficiency in people who are at greater risk.
Supplementation is also often marketed to help prevent several conditions, such as heart disease, macular degeneration, and dementia. However, there is not enough research to support these uses.
This article reviews vitamin B12, why you need it, and who should supplement with it.
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What Does Vitamin B12 Do?
Vitamin B12 has several primary functions in the human body, including:
- Development and function of the central nervous system
- Formation of red blood cells
- Synthesis of DNA and RNA
- Conversion of hom*ocysteine (an amino acid in the blood) to methionine (an essential amino acid for the body)
Most people get enough vitamin B12 from the foods they eat, but some may require additional vitamin B12 through supplementation.
Benefits of Vitamin B12 Supplements
The following are potential health benefits of vitamin B12 supplementation.
Prevent or Treat Vitamin B12 Deficiency
Vitamin B12 deficiency usually results from inadequate intake or poor absorption.
It can also occur due to pernicious anemia, an autoimmune disorder that prevents the body from absorbing vitamin B12.
People with pernicious anemia or vitamin B12 deficiency, confirmed by a blood test, should be provided supplementation until vitamin B12 levels return to normal. Your healthcare provider will give this as an intramuscular (IM) injection of vitamin B12. Once levels have returned to normal, additional oral supplementation can be added for a maintenance regimen.
If you are concerned about your vitamin B12 status, discuss it with your healthcare provider. They can help order tests to check your status and prescribe supplementation.
Pregnancy Support
Multivitamin and mineral supplementation is frequently recommended during pregnancy.
Research has found that multi-micronutrient supplementation improves maternal and child health outcomes, particularly in underdeveloped countries.
Vitamin B12 supplementation during pregnancy improves vitamin B12 status during and after pregnancy. Still, the clinical impact of this improvement in the long term and on the child's health has not been studied.
Pregnant people who are at risk of vitamin B12 deficiency should discuss their diet and supplementation options with their primary care provider for pregnancy.
For example, if you follow a vegetarian diet, you may need to check your vitamin B12 status and supplement while pregnant or breastfeeding.
Unproven Uses
Vitamin B12 has been suggested to be beneficial in several areas. Yet, there is not enough research to support supplementation of vitamin B12 for these purposes.
Heart Health
Elevated hom*ocysteine levels have been associated with increased heart disease risk. While B vitamins may lower hom*ocysteine levels, research has found no effect on reducing heart disease or cardiovascular events, including heart attack and stroke.
Macular Degeneration Risk
Like heart disease, age-related macular degeneration (AMD) is associated with elevated hom*ocysteine levels and low levels of vitamin B12. AMD is an eye condition that affects an individual's central vision.
However, no research has been conducted on the effects of vitamin B12 supplementation on AMD risk or the slowed progression of AMD.
Cognitive Function
Observational studies have suggested elevated hom*ocysteine levels were associated with the incidence of Alzheimer's disease and dementia. Additionally, low vitamin B12 levels have been associated with cognitive impairment (confusion or trouble with memory and thinking).
However, further research has not found a role for vitamin B12 deficiency and supplementation for cognitive impairment.
Clinical trials evaluating supplementation of vitamin B12 and other B vitamins had little effect on preventing cognitive decline in healthy individuals.
Supplementing vitamin B12 also had no impact on reducing the risk or slowing the progression of dementia or Alzheimer's in older adults.
Mood
Some research has suggested that low intake of B vitamins may be related to a higher risk of depression in females.
One systematic review found that supplementation with B vitamins and vitamin D may improve the symptoms associated with depression and anxiety.
However, further research on clinical trials found that vitamin B12 supplementation alone had no effect on reducing depressive symptoms or improving cognitive function.
Energy and Athletic Performance
Vitamin B12 and other B vitamins are often touted as energy and performance enhancers for athletes.
However, the research does not support this. In one study, there was no difference in the bench press and leg press lifting volume or sprint performance in those taking a supplement that included vitamin B12, folate (vitamin B9), and several other nutrients compared to a placebo (an ineffective substance given to people in a drug trial control group).
Vitamin B12 does not appear to have any beneficial effect on performance in the absence of a deficiency.
B Vitamins: What Are Their Health Benefits?
Food Sources of Vitamin B12
Good food sources of vitamin B12 often include meat and seafood. Beef liver, ground beef, and turkey are notable meats that contain a lot of vitamin B12.
If you prefer seafood, you can easily get your daily vitamin B12 requirements with 3 ounces of clams, oysters, salmon, or tuna.
Dairy products like milk, yogurt, and cheese also provide good amounts of vitamin B12. Eggs are another protein food that provides vitamin B12.
Some breakfast cereals are fortified with vitamins and minerals, including vitamin B12. Read the nutrition facts label to see if vitamin B12 has been added.
For vegetarians, nutritional yeast is an excellent source of vitamin B12.
How Much Vitamin B12 Do I Need?
There is a Recommended Dietary Allowance (RDA) set for vitamin B12 intake. The amounts vary depending on age:
- Birth to 6 months: 0.4 micrograms (mcg)
- 7 to 12 months old: 0.5 mcg
- 1 to 3 years old: 0.9 mcg
- 4 to 8 years old: 1.2 mcg
- 9 to 13 years old: 1.8 mcg
- 14 to 18 years old: 2.4 mcg
- 19 years and older: 2.4 mcg
Vitamin B12 requirements increase to 2.6 mg and 2.8 mg daily during pregnancy and lactation, respectively.
Signs and Symptoms of Vitamin B12 Deficiency
Vitamin B12 deficiency can occur due to the following:
- Inadequate intake
- Poor absorption
- Lack of intrinsic factor (a glycoprotein made by the stomach)
- Gastric acid-reducing medications
The body stores up to 5 milligrams (mg) of vitamin B12, so symptoms of a deficiency take several months to years to develop. Signs of a possible deficiency include:
- Megaloblastic anemia
- Glossitis of the tongue
- Pale skin
- Fatigue
- Heart palpitations
- Weight loss
- Dementia
- Infertility
Who Is at Risk of Vitamin B12 Deficiency?
Deficiency of vitamin B12 is typically the result of too little intake of vitamin B12-rich foods or altered/poor absorption. The following populations are at a heightened risk of vitamin B12 deficiency:
- Vegetarians or vegans: Many good food sources of vitamin B12 are derived from animal products. Meats, seafood, dairy, and eggs are all great sources. Strict vegans who avoid all these may have a greater risk of deficiency.
- Infants of vegetarians or vegans: Infants that are solely breastfed by people who are vegans, vegetarians, or are vitamin B12-deficient could also develop a vitamin B12 deficiency.
- Older adults: They may be prone to gastritis or Helicobacter pylori (H pylori) infection, which could result in reduced absorption of vitamin B12.
- People with pernicious anemia: This anemia attacks the parietal cells in the stomach, preventing the production of intrinsic factors. This results in the malabsorption of vitamin B12.
- People with gastrointestinal (GI) disorders: People with Crohn's disease or colitis may have low levels of several vitamins, including vitamin B12, due to poor absorption.
- People who have had GI surgery: People who have undergone a gastrectomy (removal of a portion of the stomach) or gastric bypass may lose the ability to absorb vitamin B12 properly. Additionally, vitamin B12 is absorbed in the ileum, so people who have undergone a small bowel resection may also be at risk of deficiency.
Do I Need to Take Supplements?
Based on the available evidence, only people with an existing deficiency or risk of developing a deficiency should take vitamin B12 supplements. This may include:
- People who are vegan or vegetarian
- Pregnant people who are vegan or vegetarian
- Older adults
- People with pernicious anemia
- People with GI disorders and/or a history of GI surgery
Otherwise, you should be able to get enough vitamin B12 through diet alone.
Before purchasing vitamin B12 supplements, discuss with your healthcare provider whether you actually need supplementation. They can help you determine whether supplements are the right choice for you, what form of supplements would be best, and recommend a proper dose.
Additionally, many supplements may interact with medications. Before starting your supplements, talk to your provider about what medications you are taking. This includes over-the-counter and prescription medications, as well as other supplements.
How to Choose a Supplement
Dietary supplements are not regulated like drugs in the United States. They can cause interactions with medications or have other safety concerns. For this reason, it’s important to be aware of what to look for when choosing a supplement, such as third-party testing, potential drug interactions, and more.
Summary
Vitamin B12 is an essential vitamin that we get from our diet. Most people can easily get enough vitamin B12 from the food they eat. However, there are a few groups of people who either don't get enough in their diet or have trouble properly absorbing vitamin B12. In these cases, they may benefit from supplementation.
Vitamin B12 supplementation is marketed for several other reasons, including heart health, eye health, cognitive decline, mood enhancement, and more. However, insufficient evidence exists to routinely supplement vitamin B12 for these conditions.
As always, discuss nutritional supplementation with your primary care provider to ensure that it is appropriate for you.
