How much Vitamin B12 do you need per day?

Vitamin B12 plays a number of crucial roles in the body. It is responsible for the healthy formation of red blood cells, DNA and our nerves, and it also has an impact on the ways in which we produce energy (National Institutes of Health, 2016). Unfortunately we are also unable to create our own Vitamin B12, which means it has to come through either our diet or supplementation. 

There are also certain medical conditions which may increase our need for B12, due to malabsorption, including Inflammatory Bowel Disease (IBD) and genetic conditions. Those with a restricted diet (particularly those which don’t contain animal products) and those on certain medications may also need to obtain their B12 from supplementation. The ideal dose per day is dependent on several factors, including age, and the reasons why you’re looking at supplementation. 

It’s not only making sure that you get enough B12 that’s important. Understanding the damage a deficiency can do to your body is also important so that you can recognise the signs. Fatigue, anaemia and nerve damage are all results of B12 deficiencies, and you can read more about the signs and symptoms of a B12 deficiency in this article.

How much Vitamin B12 do I need? 

The great thing about Vitamin B12 is that your body is able to store it for several years, so really serious deficiencies are rare, and symptoms will present themselves before any damage to your body becomes irreversible. However, it is believed that over a quarter of people may have a mild deficiency due to low levels of ingestion, which can still cause the same damage over time (Green et al., 2017).

People under 50: If you have a healthy, active lifestyle and are not taking any medication which may interfere with your ability to absorb B12, then the Recommended Daily Intake is around 1.5mcg of B12 (NHS, 2017).

Vegans and vegetarians: It is recommended that vegans and vegetarians all take a Vitamin B12 supplement. This isn’t to say that a plant-based diet is lacking in nutrition. In actual fact, people who rely on plants for their nutrition tend to have better access to a wider range of vitamins and minerals. However, animal-based products do contain the majority of B12 that we can get from our diet. That means that people who choose not to eat animal products are more at risk of a B12 deficiency. The recommendation for vegans is up to 6mcg per day according to various studies (Rogerson, 2017).

People over 50: The ability to absorb B12 decreases with age, and it is therefore recommended that people over the age of 50 use a B12 supplement to ensure that their levels of this vital nutrient remain adequate (Langan and Goodbred, 2017). Research has shown that over 60% of people over the age of 65 have lower levels of B12. As we age, our body makes less stomach acid, which is necessary for the absorption of B12 (Stover, 2010). Supplemental doses of B12 between 500-1,000mcg have been shown to help regulate B12 levels in older people (Hill et al., 2012).

Pregnant and breastfeeding women: Pregnant women need a higher level of B12 than the general population, around 2.5mcg per day. Birth defects, risk of premature birth, and a low birth weight are all associated with low levels of B12 during gestation (Rogne et al., 2017). B12 remains really important for breastfeeding infants, who can experience developmental delays, irritability and a lack of appetite if they don’t get enough. For this reason, breastfeeding women require more B12 than pregnant women - up to 2.8mcg per day (Roschitz et al., 2005).

People with chronic chronic gastrointestinal issues (such as Crohn’s and celiac disease) anyone who has received bariatric surgery, had part of their bowel removed, take acid-reducing drugs or who rely on metformin to manage diabetes may all benefit from taking higher levels of B12, but this would need to be confirmed by your healthcare provider. 

What does a functional dose of B12 look like? 

Choosing a functional dosage of B12 is really important. Most of the dosages are between 500 and 5,000 micrograms, which might seem a lot higher than the Recommended Daily Intakes mentioned above. Supplements may contain higher levels of B12 because some will be less bioavailable or made from a synthesised material, so you need to take a higher amount to make sure that your needs are met (Carmel, 2008). 

Try starting out at a mid-range dosage such as 1,000 mcg, and increase if you feel it’s needed. Daily doses are safe at these lower levels, but some people may choose to take their supplements at a higher dose once per week. Those getting prescribed injections from their doctor are likely to only need them once every few months at a very high dosage which is not meant to be used weekly or daily. 

Is B12 safe in these higher doses? 

B12 is a water soluble vitamin which is considered to be generally safe, even at higher doses. It has a low level of toxicity, and no upper limit for ingesting B12 has yet been set due to the fact that any B12 your body doesn’t use is excreted through your urine, so it doesn’t matter if you accidentally take your supplement twice in one day, for example. 

However, consistently elevated levels of B12 can be an indicator that something isn’t right in the body, and should be discussed with your healthcare provider. It could be an early indicator of certain conditions such as diabetes, liver disease or leukaemia. 

Vivo Life’s plant-based liquid B12 supplement contains 500mcg per serving of the three most active forms of vitamin B12: Methylcobalamin, Adenosylcobalamin and Hydroxocobalamin. This is to ensure optimal absorption, and supports a range of physical and psychological functions in the body. Plus, it has a really great fresh orange taste, and the liquid ensures optimal absorption by bypassing the digestive system entirely. 


National Institutes of Health (2016). Office of Dietary Supplements - Vitamin B12. [online] Nih.gov. Available at: https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/.|

Langan, R.C. and Goodbred, A.J. (2017). Vitamin B12 Deficiency: Recognition and Management. American Family Physician, [online] 96(6), pp.384–389. Available at: https://pubmed.ncbi.nlm.nih.gov/28925645/.

Green, R., Allen, L.H., Bjørke-Monsen, A.-L., Brito, A., Guéant, J.-L., Miller, J.W., Molloy, A.M., Nexo, E., Stabler, S., Toh, B.-H., Ueland, P.M. and Yajnik, C. (2017). Vitamin B12 deficiency. Nature Reviews Disease Primers, 3(1). doi:10.1038/nrdp.2017.40.

Carmel, R. (2008). How I treat cobalamin (vitamin B12) deficiency. Blood, 112(6), pp.2214–2221. doi:10.1182/blood-2008-03-040253.

nhs.uk. (2017). Vitamins and minerals - B vitamins and folic acid. [online] Available at: https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-b.

Stover, P.J. (2010). Vitamin B12 and Older Adults. Current Opinion in Clinical Nutrition and Metabolic Care, [online] 13(1), pp.24–27. doi:10.1097/mco.0b013e328333d157.

Hill, M.H., Flatley, J.E., Barker, M.E., Garner, C.M., Manning, N.J., Olpin, S.E., Moat, S.J., Russell, J. and Powers, H.J. (2012). A Vitamin B-12 Supplement of 500 μg/d for Eight Weeks Does Not Normalize Urinary Methylmalonic Acid or Other Biomarkers of Vitamin B-12 Status in Elderly People with Moderately Poor Vitamin B-12 Status. The Journal of Nutrition, 143(2), pp.142–147. doi:10.3945/jn.112.169193.

Rogne, T., Tielemans, M.J., Chong, M.F.-F., Yajnik, C.S., Krishnaveni, G.V., Poston, L., Jaddoe, V.W.V., Steegers, E.A.P., Joshi, S., Chong, Y.-S., Godfrey, K.M., Yap, F., Yahyaoui, R., Thomas, T., Hay, G., Hogeveen, M., Demir, A., Saravanan, P., Skovlund, E. and Martinussen, M.P. (2017). Associations of Maternal Vitamin B12 Concentration in Pregnancy With the Risks of Preterm Birth and Low Birth Weight: A Systematic Review and Meta-Analysis of Individual Participant Data. American Journal of Epidemiology. doi:10.1093/aje/kww212.

Roschitz, B., Plecko, B., Huemer, M., Biebl, A., Foerster, H. and Sperl, W. (2005). Nutritional infantile vitamin B12 deficiency: pathobiochemical considerations in seven patients. Archives of Disease in Childhood - Fetal and Neonatal Edition, [online] 90(3), pp.F281-FF282. doi:10.1136/adc.2004.061929.

Rogerson, D. (2017). Vegan diets: practical advice for athletes and exercisers. Journal of the International Society of Sports Nutrition, [online] 14(1). doi:10.1186/s12970-017-0192-9.