What are the benefits of taking vitamin B12? A look at its impact on health

October 6, 2025 •

4 min read

According to the NIH, an estimated 3.6% of US adults have a vitamin B12 deficiency, which can cause significant health problems. This article explores what are the benefits of taking vitamin B12 for your overall health and well-being.

Quick Summary

Vitamin B12 supports vital bodily functions, including healthy red blood cell formation, brain and nervous system function, and DNA synthesis. It helps prevent megaloblastic anemia, reduces fatigue associated with deficiency, and may support mood and cognitive function.

Key Points

Supports Red Blood Cell Production: Vitamin B12 is essential for making healthy red blood cells, preventing megaloblastic anemia, which causes fatigue and weakness.
Maintains Nervous System Health: It is crucial for nerve function and the formation of myelin, the protective sheath around nerves. Deficiency can lead to nerve damage, numbness, and tingling.
Aids Brain Function: Adequate B12 levels are linked to better cognitive function and mood, and deficiency is associated with memory loss, confusion, and depression.
Boosts Energy (if Deficient): While it won't give a boost to those with normal levels, restoring low B12 levels can effectively combat fatigue and improve energy metabolism.
Helps Create DNA: B12 is a vital component in the synthesis and regulation of DNA, the genetic blueprint of every cell in your body.
Crucial for Fetal Development: Adequate B12 intake is especially important during pregnancy to support the proper neurological development of the fetus.

The Role of Vitamin B12 in the Body

Vitamin B12, also known as cobalamin, is a crucial water-soluble vitamin that the body cannot produce on its own. It must be obtained through dietary sources or supplementation. Its importance lies in its role as a cofactor for several enzymes involved in critical metabolic processes. A consistent intake of this essential nutrient is fundamental to maintaining both physical and neurological health.

Contribution to Red Blood Cell Formation and Anemia Prevention

One of the most well-known benefits of vitamin B12 is its role in the formation of red blood cells. In conjunction with folate (vitamin B9), it is essential for the synthesis of DNA, which allows for the proper development of red blood cells in the bone marrow. A deficiency in B12 can lead to megaloblastic anemia, a condition where red blood cells are abnormally large, immature, and unable to function properly, leading to fatigue and weakness. By ensuring adequate B12 levels, the body can produce healthy red blood cells that efficiently transport oxygen throughout the body.

Supporting Brain and Nervous System Health

Vitamin B12 is vital for the development and maintenance of the central nervous system, including the brain and spinal cord. It helps in the formation of myelin, the protective sheath that insulates nerve fibers and ensures the efficient transmission of nerve impulses. A deficiency can damage this myelin sheath, leading to neurological issues such as tingling or numbness in the hands and feet, difficulty with balance, and memory problems. By supporting the health of nerves, B12 contributes to overall neurological function and protection.

Role in DNA Synthesis and Regulation

Beyond its function in red blood cell production, vitamin B12 is a core component in the process of DNA synthesis and regulation. It works with other B vitamins to create and repair DNA, the genetic material found in all cells. This process is fundamental for cell growth, division, and overall health. Proper DNA synthesis is crucial for all bodily functions, making B12's role indispensable.

Boosting Energy Metabolism

Many B12 supplements are marketed for energy-boosting properties. While they don't provide a sudden burst of energy, B12 plays a critical role in converting the food we eat into usable energy. If you have a deficiency, replenishing your B12 levels can reduce fatigue and combat low energy. The energy-related benefit is most significant for individuals whose tiredness is a symptom of a deficiency, rather than for those who already have normal levels.

Health Benefits of Optimal B12 Levels

Maintaining sufficient vitamin B12 levels can contribute to several other health benefits:

Mood Enhancement: Studies have shown a correlation between low vitamin B12 levels and depression, suggesting B12 supplementation may improve mood in deficient individuals. B12 is involved in the synthesis of neurotransmitters that regulate mood.
Bone Health Support: Research has linked low levels of B12 to increased risk of osteoporosis, a condition that weakens bones. While more studies are needed, maintaining adequate levels may help support bone density.
Macular Degeneration Prevention: Some studies suggest that B12 may play a role in reducing the risk of age-related macular degeneration (AMD), an eye disease that can cause vision loss.
Fetal Development: Vitamin B12 is essential during pregnancy for proper brain and spinal cord development in the fetus. Deficiency in mothers can lead to developmental delays and failure to thrive in infants.

Vitamin B12: Food vs. Supplements

Comparison of B12 Sources

For most people, a balanced diet that includes animal products is sufficient to meet their B12 needs. However, certain groups may require supplements to ensure adequate intake.


Source Type	Examples	Recommended for	Considerations
Animal Foods	Beef, liver, clams, salmon, tuna, eggs, dairy products	Most people without absorption issues	B12 is bound to proteins and requires stomach acid and intrinsic factor for absorption.
Fortified Foods	Fortified breakfast cereals, nutritional yeast, plant-based milks	Vegans, vegetarians, older adults	B12 is in a free, more easily absorbed form. Content can vary, so always check labels.
Oral Supplements	Pills, sublingual tablets, lozenges	Vegans, vegetarians, older adults, individuals with absorption issues	Absorption depends on stomach function; high doses are needed to allow for some passive absorption.
Injections or Nasal Gels	Prescription injections, nasal sprays	Individuals with pernicious anemia or severe absorption disorders	Bypasses the need for intrinsic factor. Administered by a healthcare professional.

Who Needs Vitamin B12 Supplements?

Several factors can impair the body's ability to absorb B12 from food, making supplementation necessary. Individuals at higher risk of deficiency include:

Older Adults: The ability to absorb B12 from food can decrease with age due to reduced stomach acid production.
Vegans and Vegetarians: Since B12 is primarily found in animal products, plant-based diets require careful planning and supplementation.
People with Gastrointestinal Disorders: Conditions like celiac disease and Crohn's disease can interfere with B12 absorption.
Post-Surgery Patients: Individuals who have undergone stomach or intestinal surgery may have impaired absorption.
Those with Pernicious Anemia: This autoimmune condition prevents the production of intrinsic factor, a protein necessary for B12 absorption.
Individuals on Certain Medications: Long-term use of certain drugs, such as metformin and acid-reducing medications, can affect B12 absorption.

Conclusion: Prioritizing Your Vitamin B12 Intake

Vitamin B12 is a powerhouse nutrient essential for countless bodily functions, from the production of red blood cells and DNA to the maintenance of a healthy nervous system. While most people can obtain sufficient B12 through a balanced diet including animal products, certain populations, such as older adults, vegans, and those with specific medical conditions, are at a higher risk of deficiency. For these individuals, supplements or fortified foods are crucial for maintaining optimal health. If you suspect a deficiency due to symptoms like fatigue, weakness, or neurological issues, a healthcare provider can conduct a blood test to determine the right course of action. Proactively managing your B12 intake is a smart and effective way to protect your long-term health and well-being. For more detailed information on vitamin B12, consult the National Institutes of Health (NIH) Office of Dietary Supplements.

Frequently Asked Questions

Symptoms of a B12 deficiency can include fatigue, weakness, pale or yellowish skin, a sore and red tongue (glossitis), tingling in the hands and feet, difficulty walking, and mood changes like depression or irritability.

Vitamin B12 is found naturally in animal products. Top sources include beef liver, clams, fish (like salmon and tuna), meat, poultry, eggs, and dairy products (milk, cheese, yogurt).

Yes, but only through fortified foods. Vitamin B12 is not naturally found in plants. Plant-based sources include fortified nutritional yeast, breakfast cereals, and plant-based milks. Vegans and vegetarians often need to rely on these or supplements.

The body absorbs B12 from food in a two-step process. First, stomach acid releases B12 from its protein. It then binds to a protein called intrinsic factor, which is produced in the stomach, and is absorbed in the small intestine.

People most at risk include older adults, vegans and vegetarians, individuals with gastrointestinal disorders like Crohn's disease or celiac disease, and those who have had stomach surgery. Some medications can also interfere with absorption.

For those with a confirmed deficiency, a healthcare provider may recommend injections, which raise levels faster than oral supplements by bypassing absorption barriers. Dietary changes and oral supplements can also be effective.

Vitamin B12 is a water-soluble vitamin, so any excess is typically excreted in the urine. While high doses from supplements are considered safe, there is no benefit to taking more than you need, and some sources suggest excessive intake could cause side effects like acne.