B12 is one of those vitamins everyone has heard of and few people can explain. It does a handful of essential jobs, it's easy to run short on in certain situations, and it's also one of the most over-hyped nutrients on the shelf. Here's the clear version.
Written by Vita Globe Editorial Team | Reviewed against NIH guidance and peer-reviewed research
What is vitamin B12 good for?
Vitamin B12 is needed to make healthy red blood cells, to build and maintain the nervous system (including the myelin that insulates nerves), and to make DNA[1]. It also helps the body turn food into usable energy at the cellular level. Your body can't make B12, so it has to come from animal foods, fortified foods or supplements[1][2].
Caveat: If your B12 levels are already normal, taking more hasn't been shown to boost energy, mood or memory[3].
Sources: NIH ODS · Green et al., 2017 · Markun et al., 2021 · Verified 2026-09-27
IN THIS ARTICLE
What does vitamin B12 actually do?
Vitamin B12 (also called cobalamin) is a water-soluble vitamin with a short but important job list. According to the NIH Office of Dietary Supplements, it is required for healthy red blood cell formation, for DNA synthesis, and for the development, myelination and function of the central nervous system[1].
Under the hood, B12 works as a helper (a "cofactor") for two enzymes. One helps recycle folate and convert homocysteine to methionine; the other helps the body process certain fats and amino acids for energy[2]. When B12 runs low, those pathways stall, which is why deficiency shows up in the blood and the nerves at the same time.
Is B12 good for energy?
This is the most common reason people reach for B12, so it is worth being precise. B12 plays a real role in energy metabolism, and fatigue is a classic symptom of deficiency, often because low B12 can lead to a type of anemia where red blood cells are too few and too large[4].
But "B12 is needed for energy" is not the same as "extra B12 gives you more energy." A 2021 systematic review and meta-analysis of randomized trials found no benefit of B12 supplementation on cognitive function or depressive symptoms in people without advanced neurological disorders, and there wasn't enough data to judge effects on fatigue[3]. We go deeper on this in Vitamin B12 and Energy: What It Actually Does and Does B12 Actually Give You Energy?.
Who is most likely to benefit from B12?
B12 matters most for people who are likely to fall short. The NIH lists these groups as higher risk[1]:
- Older adults, who are more likely to have reduced stomach acid and trouble absorbing B12 from food (why absorption drops after 50).
- Vegans and many vegetarians, since B12 occurs naturally only in animal foods (B12 for vegans and vegetarians).
- People with pernicious anemia or gastrointestinal conditions or surgery that affect absorption.
- People taking certain medications long term, such as metformin or acid-reducing drugs (B12 and metformin).
In the U.S., the NIH estimates that about 3.6% of adults have B12 deficiency and about 12.5% have insufficiency[1]. For the full breakdown of symptoms, see Vitamin B12 Deficiency: Signs, Causes, and What Actually Helps.
What B12 is not good for
A lot of B12 marketing leans on claims the evidence doesn't support for people with normal levels. Weight loss, "detox," all-day energy and sharper memory are the usual suspects. The better-quality research points one way: correcting a real deficiency matters a lot, while topping up an already-adequate level does little that you'd notice[3][1].
The honest summary
- B12 is essential for red blood cells, nerves, DNA and energy metabolism.
- Deficiency can cause fatigue, anemia and nerve symptoms, and it's more common than many people think in certain groups.
- If your levels are fine, extra B12 is unlikely to change how you feel.
- If you have symptoms, a blood test is more useful than guessing.
How do you get enough B12?
Most adults need 2.4 mcg a day; the target is a little higher in pregnancy (2.6 mcg) and breastfeeding (2.8 mcg)[1]. Meat, fish, eggs and dairy are natural sources, and many cereals and plant milks are fortified. Our guide to the best food sources of B12 lists the richest options. For how much is enough (and why supplements often contain far more), see How Much B12 Per Day Do You Need?.
Our option
Vita Globe Vitamin B12 Gummies for Adults
Our B12 Gummies for Adults provide 1,000mcg of vitamin B12 (as cyanocobalamin) per two-gummy serving, in a chewable gummy that is vegan-friendly, gluten-free and non-GMO. B12 supports red blood cell formation and cellular energy production.* If you need B12 on the go, the same 1,000mcg-per-serving formula also comes in a resealable travel pouch.
Frequently asked questions
What are the signs you need B12?
Common signs of deficiency include fatigue, weakness, pale skin, a sore tongue, numbness or tingling in the hands and feet, and memory or mood changes[1][4]. These symptoms have many possible causes, so a blood test is the only way to know.
Is it OK to take B12 every day?
For most healthy adults, yes. No upper limit has been set for B12 because of its low potential for toxicity[1]. Check with your provider if you take medication or have a medical condition.
Does B12 help you lose weight?
There is no good evidence that B12 causes weight loss in people who aren't deficient[1].
Does B12 help with hair, skin or nails?
Severe deficiency can affect skin and hair, but there is no strong evidence that extra B12 improves hair, skin or nails in people with normal levels.
Is B12 better on its own or in a B-complex?
It depends on your goal. If B12 is the nutrient you are low in, a single B12 is simple. We compare the options in Is B-Complex Actually Better Than a Single B Vitamin?
Sources
- Office of Dietary Supplements, National Institutes of Health. Vitamin B12: Fact Sheet for Health Professionals. Updated July 2, 2025. ods.od.nih.gov
- Green R, Allen LH, Bjørke-Monsen AL, et al. Vitamin B12 deficiency. Nat Rev Dis Primers. 2017;3:17040. doi:10.1038/nrdp.2017.40
- Markun S, Gravestock I, Jäger L, Rosemann T, Pichierri G, Burgstaller JM. Effects of vitamin B12 supplementation on cognitive function, depressive symptoms, and fatigue: a systematic review, meta-analysis, and meta-regression. Nutrients. 2021;13(3):923. doi:10.3390/nu13030923
- Stabler SP. Vitamin B12 deficiency. N Engl J Med. 2013;368(2):149-160. doi:10.1056/NEJMcp1113996
About the Vita Globe Editorial Team
The Vita Globe Editorial Team researches and writes our wellness content, working from peer-reviewed research, systematic reviews and guidance from bodies such as the NIH and the FDA. We cite our sources inline and update articles when the evidence changes.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. This article is for informational purposes only and is not a substitute for medical advice. Talk to your healthcare provider before starting any new supplement, particularly if you are pregnant, nursing, taking medication, or caring for a child.
