A B vitamin found almost only in animal foods, so vegans and older adults are often low.
Why it’s used: Contributes to the reduction of tiredness and fatigue, normal energy-yielding metabolism and normal psychological function.
Vitamin B12 is a B vitamin found naturally almost only in animal foods: meat, fish, milk, cheese and eggs. Some breakfast cereals are fortified with it. Because it is not found naturally in fruit, vegetables or grains, people who follow a vegan diet may not get enough from food alone.
Vitamin B12 helps the body make red blood cells, keep the nervous system healthy, release energy from food and use folate. It contributes to the reduction of tiredness and fatigue, normal energy-yielding metabolism and normal psychological function.
Some groups are more likely to have low levels. The NIH lists many adults over 50, people with pernicious anaemia or atrophic gastritis, people with coeliac disease or Crohn's disease, people who have had some types of stomach or bowel surgery, and vegetarians and vegans. On labels you will usually see cyanocobalamin or methylcobalamin, and sometimes hydroxocobalamin or adenosylcobalamin. Amounts are listed in micrograms (µg), and supplements often provide far more than the small daily need.
3 findings behind this ingredient. Hover a card for the detail and the source.
Cochrane review of three randomised trials with 153 participants over 3–4 months. 1,000 µg a day by mouth was comparable to intramuscular B12 and 2,000 µg a day gave higher levels; evidence quality was low.
Randomised, double-blind trial of 40 vegans and vegetarians over 12 weeks comparing 350 µg a week with 2,000 µg a week. Both raised serum B12 and holotranscobalamin and lowered methylmalonic acid and homocysteine, with no difference between doses.
Randomised, double-blind dose-finding trial in 120 older people with mild deficiency taking 2.5 to 1,000 µg cyanocobalamin daily for 16 weeks. Doses of 647–1,032 µg gave 80–90% of the maximum fall in methylmalonic acid.
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Vitamin B12 is found naturally almost only in animal foods, so people who eat little or no animal produce may not get enough. The NIH lists vegetarians and vegans among the groups at risk of low levels. Fortified foods or a supplement can help fill that gap.
Both are forms of vitamin B12 used in supplements, alongside hydroxocobalamin and adenosylcobalamin. Whichever form a product uses, vitamin B12 contributes to normal energy-yielding metabolism and the reduction of tiredness and fatigue. The amount and how regularly you take it matter most.
Vitamin B12 has not been shown to cause harm, even at high doses, according to the NIH. The NHS says 2mg or less a day from supplements is unlikely to cause any harm. Adults need only about 1.5 micrograms a day.
Videos from doctors, research scientists and registered dietitians, for general education. They are independent of Nutra Formulations, do not refer to our products and are not medical advice for you.
The Optimal Vitamin B12 Dosage for Adults
Dr Michael Greger, MD, FACLM · NutritionFacts.org on YouTube
7 Signs of B12 Deficiency Doctors Often Miss
Dr Ken Berry, MD, board-certified family physician · KenDBerryMD on YouTube
Information only, not medical advice. If you take medication, are pregnant or breastfeeding, speak to your GP or pharmacist first.
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