Vitamin B12

This vitamin is used by the body to manufacture red blood cells, DNA, nerves and to perform other vital functions.  It cannot be made by the body, and has to be obtained from food.

Deficiencies pf vitamin B12 are common, particularly in those over 50 or those following a vegetarian or a vegan diet. This is because the best sources of B12 are animal-derived foods like meat, poultry, eggs and dairy products (especially Swiss cheese). There is no vitamin B12 in most plant-based foods, though some fungi and mushrooms have it, as well as fermented plant products like tempeh and miso. Some grain products like wholemeal bread are fortified with B12, and yeast contains it too.  Some soy milks are also fortified with B12. The recommended amount of B12 for an adult is 2.4 micrograms a day.

Vitamin B12 has a role in the human cardiovascular system, particularly in the production of red blood cells, which is why a deficiency of this vitamin can cause anemia. It is also involved in the production of DNA, and through its role in the maintenace of hemoglobin in red blood cells, in brain health as well.

Some people don’t get enough B12 in their diet, and some, due to medical conditions, can’t absorb it well even if they do get enough in their food.  Weight loss surgery and stomach stapling can also induce deficiencies as absorbtion is reduced.  Harvard Medical School lists these signs of vitamin B12 deficiency:

  • strange sensations, numbness, or tingling in the hands, legs, or feet
  • difficulty walking (staggering, balance problems)
  • anemia
  • a swollen, inflamed tongue
  • yellowed skin (jaundice)
  • difficulty thinking and reasoning (cognitive difficulties), or memory loss
  • paranoia or hallucinations
  • weakness
  • fatigue      (1)

It goes without saying that if you have these symptoms you should see your doctor as soon as possible.

In addition, those who take antacids for reflux may develop a B12 deficiency, as acid is needed for the body to absorb B12 from food and these medications reduce the stomach’s natural acidity.

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While mild B12 deficiency can be treated with supplements, more serious deficiencies may need weekly injections.

In addition, the American Dietetic Association, in a Practitioners’ Guide, stated that many people aged 51 or older may have B12 malabsorption issues.  This is likely caused by  lack of pepsin activity and gastric acid production , which are necessary for the release of vitamin B-12 from protein. In its recommendations, the Guide says

“Dietitians and health care professionals should recognize that many cases of vitamin B-12 deficiency may be undiagnosed. Although only 10% to 30% of older adults are estimated to have protein-bound vitamin B-12 malabsorption, all people in this age group should be considered at risk for this condition. Recommendations to consume the majority of the RDA as synthetic vitamin B-12 should be given to people in this age group.” (2)

If you are a lacto-vegetarian and would rather try to ensure adequate intake B12 from food, you can follow the advice of another nutritionist on Healthaliciousness and eat more foods like Swiss cheese, eggs, whey, milk and yoghurt and yeast spreads like Marmite. (3)


  2. Practitioners’ Guide to Meeting the Vitamin B-12 Recommended Dietary Allowance for People Aged 51 Years and Older