Vitamin B12 helps your body make red blood cells, keeps your nervous system working normally and helps release energy from food. Adults need about 4 µg a day. Because B12 is found almost only in animal foods, vegans, many vegetarians and many people over 50 are at risk of running low. Here is what B12 does, how to recognise a deficiency, who should consider a supplement and how much is enough.
Key facts about vitamin B12
- Vitamin B12 (cobalamin) is a water-soluble vitamin your body cannot make itself.
- The European Food Safety Authority (EFSA) and the German, Austrian and Swiss nutrition societies recommend 4 µg per day for adults.
- Natural sources are meat, fish, eggs and dairy products; plant foods only contain B12 if they are fortified.
- Your liver stores B12 for several years, so a deficiency can develop slowly and go unnoticed.
- There is no known upper limit: excess B12 from food or supplements is considered safe.
What does vitamin B12 do? Its main benefits
In the European Union and Switzerland, the following health claims are authorised for vitamin B12. It contributes to:
- normal red blood cell formation: without enough B12, red blood cells become large and too few, a form of anaemia that causes tiredness and weakness;
- normal functioning of the nervous system: B12 is needed to maintain the protective layer around nerve fibres;
- normal psychological function, including concentration and memory;
- normal energy-yielding metabolism and the reduction of tiredness and fatigue;
- normal homocysteine metabolism;
- normal function of the immune system;
- the process of cell division, which is why B12 is important during pregnancy.
Signs of vitamin B12 deficiency
A lack of vitamin B12 develops gradually. Common signs include:
- extreme tiredness and a lack of energy
- pins and needles or numbness in hands and feet
- a sore, red tongue and mouth ulcers
- muscle weakness
- problems with vision
- low mood, irritability, and problems with memory and concentration
- pale skin and shortness of breath
Nerve damage caused by a long-lasting B12 deficiency can become permanent, so do not ignore these symptoms. A doctor can check your B12 status with a blood test. If a deficiency is found, it is usually treated with high-dose tablets or injections under medical supervision.
Who is at risk of low vitamin B12?
- Vegans and vegetarians: without fortified foods or a supplement, a vegan diet provides almost no B12.
- Adults over 50: with age, the stomach often produces less acid, which is needed to release B12 from food.
- People with stomach or gut conditions, such as atrophic gastritis, pernicious anaemia, coeliac disease, Crohn's disease, or after stomach or bowel surgery.
- People taking certain medicines for a long time, such as metformin or acid-reducing medicines (proton pump inhibitors).
- Pregnant and breastfeeding women on a plant-based diet, because the baby depends on the mother's B12.
How much vitamin B12 do you need per day?
EFSA and the D-A-CH reference values recommend 4 µg per day for adults. The D-A-CH values rise to 4.5 µg during pregnancy and 5.5 µg while breastfeeding. The nutrient reference value (NRV) on European food labels is 2.5 µg. In the United States the recommendation is 2.4 µg.
Your body absorbs only a small amount of B12 at a time, so several moderate doses across the day are used more efficiently than one large dose. This is one reason why splitting B12 between a morning and an evening supplement makes sense.
Best food sources of vitamin B12
- liver, beef and lamb
- fish and seafood, such as salmon, trout, tuna and clams
- eggs
- milk, yoghurt and cheese
- fortified plant drinks, breakfast cereals and nutritional yeast
Seaweed, spirulina and fermented foods are often described as B12 sources, but they mostly contain forms of B12 that the human body cannot use. They are not a reliable source for vegans.
Is vitamin B12 safe? Can you take too much?
Vitamin B12 has a very low risk of harm, and no upper intake level has been set. Two points are still worth knowing:
- High doses of folic acid can mask the anaemia caused by B12 deficiency while the nerve damage continues. That is why folic acid and B12 are best taken together in balanced amounts.
- A very high B12 level in a blood test without supplement use should be discussed with your doctor.
Vitamin B12 in Sanbera formulas
All four Sanbera formulas contain vitamin B12 together with folic acid and the other B vitamins. One daily serving (3 tablets) provides:
- Daily Essential Women: 1.87 µg (75% NRV)
- Nightly Reload Women: 1.88 µg (75% NRV)
- Daily Essential Men: 1.9 µg (76% NRV)
- Nightly Reload Men: 2.34 µg (94% NRV)
A day and a night formula together provide about 3.8 to 4.2 µg, in line with the daily recommendation for adults and split into two doses. Sanbera formulas are vegan. If you have been diagnosed with a B12 deficiency, follow your doctor's treatment plan: a multivitamin is not a treatment for deficiency.
Frequently asked questions
Does vitamin B12 give you energy?
Vitamin B12 contributes to normal energy-yielding metabolism and to the reduction of tiredness and fatigue. If your levels are low, correcting them can make a real difference. If they are already normal, extra B12 will not give you more energy.
Is vitamin B12 good for hair and skin?
A severe B12 deficiency can affect skin colour and, together with anaemia, hair. In people with normal levels, there is no good evidence that extra B12 improves hair or skin.
When is the best time to take vitamin B12?
Any time of day works. Taking it with a meal and splitting it into two smaller doses can improve absorption.
How long does it take to correct low vitamin B12?
With medical treatment, blood values usually improve within weeks, and many people feel better within a few weeks. Nerve symptoms can take months to improve.
Sources
- National Institutes of Health, Office of Dietary Supplements: Vitamin B12, Health Professional Fact Sheet
- NHS: Vitamin B12 or folate deficiency anaemia
- German Nutrition Society (DGE): Reference values for nutrient intake
- European Commission: EU Register of nutrition and health claims
This article is for general information and does not replace advice from a doctor or pharmacist. Food supplements are not a substitute for a varied, balanced diet and a healthy lifestyle.