The Ultimate Guide to Vitamin B12: Benefits, Drawbacks and Who It’s Best For
Vitamin B12 is one of the clearest examples of a nutrient where the main question is not whether it matters, but whether a person is actually getting enough. The strongest evidence is for preventing and correcting deficiency, which can affect blood formation and the nervous system. Claims that B12 broadly boosts energy or mood are more conditional: they are most credible when low intake or poor absorption is already part of the picture.
That distinction matters because B12 status is shaped by diet, age and gut health rather than by diet alone. People who avoid animal foods are an obvious group to watch, but older adults and anyone with absorption problems may also be at risk even if their diets look reasonable. In practice, this makes testing more useful than guessing, especially when symptoms are vague and overlap with many other causes.
Another useful lens is safety and form. Supplements, fortified foods and injections are not interchangeable in every situation. Oral B12 is often practical for prevention, while injections are more relevant when absorption is impaired. The trade-off is that stronger delivery does not automatically mean better for everyone; cost, convenience and side effects all matter.
The most evidence-informed takeaway is to match the source to the problem. B12 is best viewed as a targeted nutrient, not a universal wellness booster. For readers trying to act on this information, the key questions are whether intake is low, whether absorption is compromised and whether any symptoms warrant clinical evaluation rather than self-treatment.
Your DNA needs vitamin B12 (cobalamin) for proper development. Along with DNA formation, vitamin B12 helps yourย body produce red blood cells, improve nerve function and help cells’ metabolism. You can find this vitamin in foods like poultry, fish, fortified breakfast cereals or dairy products.
While some people receive enough nutrition from their diets for healthy vitamin B12 levels, vegans or vegetarians might struggle to receive the daily dosage needed since B12 isn’t found in plant foods. A vitamin B12 deficiency can lead to amnesia, muscle weakness, nerve damage, intestinal problems or mood issues.
Our guide can help you better understand vitamin B12. We’ll also cover its benefits, risks from deficiency, who should consider it, and the difference between supplements and injections.
What is vitamin B12?
Vitamin B12 contains cobalt, hence its name, cobalamin. It is a vitamin your body uses toย create red blood cells and DNA. It also helps develop your central nervous system. Your central nervous system is like your body’s mail delivery system, carrying messages from your nerves to your brain, where your brain responds. Moreover, the vitamin helps your hair, nails and skin remain healthy. You can find B12 in four chemical compounds: methylcobalamin, hydroxocobalamin, adenosylcobalamin and cyanocobalamin. Methylcobalamin and adenosylcobalamin are in meat and dairy products. You might have to take a vitamin B12 supplement to avoid a B12 deficiency if you’re a vegan or vegetarian. Cyanocobalamin is theย synthetic form of Vitamin B12, broken down into methylcobalamin and adenosylcobalamin in supplements. Meanwhile, if you have a vitamin B12 deficiency, you might require a shot or IV drip. This is where hydroxocobalamin comes into play. It is a bioavailable version of the vitamin used to treat deficiencies.Benefits of vitamin B12
Taking healthy doses of vitamin B12 can benefit your body in the following ways:Supports red blood cell formation
Your body needs red blood cells to make DNA. Your body losesย 1% of your oldest red blood cells daily. Vitamin B12 with vitamin B9 (folate) helps your body replenish the red blood cells you lost. Without a healthy dose of regular vitamin B12, you can become anemic.Boosts energy levels
Some energy drinks use vitamin B12 to give you a pep in your step. However, they only work well if you have aย vitamin B-12 deficiency. When this happens, you might experience fatigue, tiredness and become cranky. Proper vitamin B12 levels from food or supplements can give your body the perk to tackle your tasks.Supports nerve health
Taking regular doses can help your nervous system. Vitamin B12 has a rep for being a neurotropic vitamin for its ability toย heal damaged nerve cells. When you take the vitamin, it contains myelin. Myelin is a sheath surrounding nerve fibers, allowing for better communication between them and the brain. It is why some of the problems with vitamin B12 deficiencies include numb toes or fingers, muscle weakness and problems with coordination. JUAN GAERTNER/SCIENCE PHOTO LIBRARY?/Getty ImagesImproves mood and cognitive function
Vitamin B12 helps play a role in the brain producing chemicals that impact your mood. While studies show low vitamin levels can lead to depression, they can’t determine ifย regulated vitamin levels boost mood or improve cognitive function.Potential risks of vitamin B12 deficiency
When your body doesn’t receive enough vitamin B12, you could be susceptible to the following medical conditions:Anemia and related symptoms
When your body doesn’t receive enough vitamin B12, it slows the growth of red blood cells. You lose 1% of your oldest red blood cells every day. Over time, it can result inย vitamin B12 deficiency anemia. With it, you can experience muscle weakness and fatigue. Insufficient vitamin B12 intake can slow the production of red blood cells. This continual loss of production may eventually lead to vitamin B12 deficiency anemia, characterized by symptoms such as muscle weakness and fatigue.Neurological issues
A lack of vitamin B12 in your body could result in neurological issues. Some of the symptoms include:- Memory loss
- Vision problems
- Ataxia, which is a condition where you lose physical coordination
- Damage to the central nervous system, especially in your legs
Long-term health risks
Many symptoms of vitamin B12 deficiencies could mimic other illnesses, making it hard to identify. If left untreated, it could lead to more serious health issues, which canย increase in severity quickly. Some of the top risks include a decline in cognitive function. More specifically, memory loss or trouble reasoning can occur. It could also result in strange sensations like tingling in your arms or feet or a swollen tongue. If you notice these symptoms, consult your doctor on root causes.Who should consider vitamin B12 supplementation?
Here are a few groups who should consider vitamin B12 supplementation:- Vegans and vegetarians: You’ll find vitamin B12 in fish, poultry and other meats. The only issue is if your diet restricts you from consuming these items, you need another source of vitamin B12. You can find these in fortified foods likeย breakfast cereals or dairy products.
- Older adults: As you age, yourย stomach acid declines, making it more difficult for your body to absorb vitamin B12 from foods. It is wise to consider a supplement if your levels are low.
- Individuals with certain medical conditions: Some medical conditions, such as celiac disease, pernicious anemia and Crohn’s, make it difficult for your body to absorb vitamin B12. In each of these instances, your doctor might recommend a shot or IV drip.
Best food sources of vitamin B12
You can find vitamin B12 in the following sources: Animal-based sources: Meat, chicken, fish, clams, salmon, sardines, tuna, trout and dairy products all contain vitamin B12. Some organ meats, like kidney and liver, areย also high in vitamin B12. Plant-based sources: Vegans and vegetarians who can’t source their vitamins from meat can consume seaweed or nutritional yeast. Nutritional yeast is good as aย popcorn topping or sprinkle it onto tofu or other plant-based foods. Fortified foods: It is where manufacturers add vitamins to the food to make it more nutritious. Fortified breakfast cereals, such as one cup of Malt-O-Meal Raisin Bran, contain more thanย 60% of your daily allotment of vitamin B12. SCIENCE PHOTO LIBRARY/Getty ImagesB12 injections vs. B12 supplements
There are many factors at play when considering injections and supplements. On the supplement front, it’s imperative to consider any medical conditions that might impede your body’s ability to absorb it. If you have Chron’s, you want a shot instead because it absorbs into your bloodstream, making it a more effective absorption method. However, when considering shots, you’ll want to consider a few things. One, they’ll be more expensive than vitamin B12 supplements. They can also cause side effects, such asย skin rashes, headaches, itching, diarrhea and nausea. Meanwhile, supplements are more cost-effective if you don’t have a medical condition where you’ll need help with absorption. However, refrain from taking them before speaking with your doctor if you’re onย folic acid supplements or if you have sensitivities to cobalt. Ultimately, your doctor can help you determine the best course of action. Expect to take a blood test to check your vitamin B12 levels before adding a supplement or shot.Tips for absorption and proper dosage
One of the best ways to maximize absorption is through proper gut health. Before trying supplements, ensure your gut doesn’t experience regular diarrhea, constipation or other issues, which can prevent your body from absorbing the vitamin well. If your doctor is okay with you taking a supplement, follow the instructions on the label. The daily recommended dose of vitamin B12 isย 2.4 micrograms. If you eat a well-balanced diet full of chicken, seafood or eggs, you’ll receive this dosage through your diet. If you need a vitamin B12 supplement, be aware of other nutrients that can lessen its effectiveness. Vitamin C supplements have the opposite effect,ย lowering the vitamin B12 in your body. Having a medical professional weigh in before taking a supplement or shot helps you cover all your bases and avoid any drug or nutrient interactions.Enjoyed this article? Sign up for our newsletter to receive regular insights and stay connected.