Vitamin B12 Low Dose: 3-50 MCG

Minimal dose 

Vitamin B12 Low Dose: 3-50 MCG

Vitamin B12 low dose: when is a low dose of 3-50 mcg of B12 enough to cover the daily requirement? In which cases should the dose be higher?

Low Dose Vitamin B12

A low dose of vitamin B12 can be a useful extra provision, but will often fail to cover the body’s daily requirement. In most cases, a higher B12 dosage is needed to obtain all the benefits of a sufficient B12 supply.

Additional Dose for Healthy People

The Institute of Medicine (IOM) set the daily requirement of vitamin B12 for healthy people at 2.5 µg per day (1); new scientific studies disagree and suggest a recommended dietary allowance (RDA) of around 4 – 7 µg taken in multiple small doses throughout the day (2). The international Vegan Society suggests a higher quantity still for vegans of at least 10 µg per day (3).

In our opinion, however, such doses should be seen as the absolute minimum for oral supplements; in idea circumstances, this amount is sufficient for preventing vitamin B12 deficiency in healthy people. 

It is worth pointing out that even mild health impairments can mean that this vitamin B12 dose is no longer enough to cover the body’s daily need – let alone enough to sufficiently fill up the body’s B12 store. In such cases, a medium dose (100 – 250 µg) or high dose (300-500 µg) is more suitable, as it will cover the body’s daily requirement in almost all cases. 

Low Doses do not Always Cover the RDA

Many vitamin experts remain doubtful as to whether a low dosage of vitamin B12 is really enough for the average person. In older people, for example, it has been proven that daily doses of 300 µg produce significant improvement, while only doses of 600 µg achieve the complete normalisation of blood levels (4). These cases are certainly at the extreme, but still provide insight into how different the demand can be. So, when is a minimum dose sufficient?

Low Dose Profile

Oral supplements containing a low dosage of B12 suffice for those who have:

  • Very good health – in particular regarding the stomach and intestines, low chance of infection etc.
  • Very healthy lifestyle – good diet, no smoking, no alcohol etc.
  • Low stress levels – no body related stress such as intense sport/physical activity or illness, no emotional stress or life crises, balanced work life, regular sleeping pattern
  • Additional dietary intake of B12

People who do not fit into this category should opt for a dose between 250 – 500 µg. Those suffering from a chronic disease or who require B12 for therapeutic purposes are recommended a much higher dose between 1000 – 2000 µg.

The information contained in this article is regarding oral supplements – recommended doses for vitamin B12 injections are provided in a separate text.


  1. Institute of Medicine, Food and Nutrition Board, National Academies of Science, Dietary Reference Intakes (DRI): Recommended Dietary Allowances and Adequate Intakes, USA 2018,  
  2. Mustafa Vakur Bor, Kristina M von Castel-Roberts, Gail PA Kauwell, Sally P Stabler, Robert H Allen, David R Maneval, Lynn B Bailey Ebba Nexo „Daily intake of 4 to 7 µg dietary vitamin B-12 is associated with steady concentrations of vitamin B-12–related biomarkers in a healthy young population“ Am J Clin Nutr 2010 91: 3 571-577; First published online January 13, 2010. doi:10.3945/ajcn.2009.28082.
  4. Eussen SM, de Groot LM, Clarke R, et al. Oral Cyanocobalamin Supplementation in Older People With Vitamin B12 Deficiency: A Dose-Finding Trial. Arch Intern Med. 2005;165(10):1167-1172. doi:10.1001/archinte.165.10.1167.