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Vitamin B12

Dr Karen Martin
Reviewed by Dr Karen MartinReviewed on 19.10.2023 | 2 minutes read

Vitamin B12 (cyanocobalamin) is a water-soluble vitamin essential for your body’s metabolism. Most of the time, it is given as tablets and oral mouth sprays; however, it is poorly absorbed, so injections are often given to deficient patients. Most people do obtain it from their regularly sourced meats and fish. Because it is so important for the body’s metabolism, people often feel exhausted when lacking in Vitamin B12. It is also for the functioning of normal blood cells and more specifically important for athletes.

Who is it for and how does it work?

Because most of Vitamin B12 comes from fish and meat, vegans and vegetarians are often advised to consume a dietary supplement or fortified foods for Vitamin B12 intake or risk serious health consequences. The most common cause of Vitamin B12 deficiency is impaired absorption due to a loss of a vital product produced in the stomach, which binds to the food containing Vitamin B12 to absorb it. A second major cause is an age-related decline in stomach acid production because acid exposure frees protein-bound vitamins. For the same reason, people on long-term antacid therapy using proton-pump inhibitors such as omeprazole or other antacids are at increased risk.

Recommended amounts

These are the recommended daily amounts:

  • 0-6 months - 0.4 mcg
  • 7-12 months - 0.5 mcg
  • 1-3 years - 0.9 mcg
  • 4-8 years - 1.2 mcg
  • 9-13 years - 1.8 mcg
  • 14 years and older - 2.4 mcg

Nutritional amounts in various foods

  • Clams, cooked, 3 ounces - 3,504%
  • Liver, beef, cooked, 3 ounces - 2,946%
  • Trout, rainbow, wild, cooked, 3 ounces - 225%
  • Salmon, sockeye, cooked, 3 ounces - 200%
  • Tuna fish, light, canned in water, 3 ounces - 104%
  • Nutritional yogurts, fortified with Vitamin B12, 1 serving - 100%
  • Cheeseburger, double patty and bun, 1 sandwich - 88%
  • Milk, low-fat, 1 cup - 50%
  • Yogurt, fruit, low-fat, 8 ounces - 46%

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This article has been written by UK-based doctors and pharmacists, so some advice may not apply to US users and some suggested treatments may not be available. For more information, please see our T&Cs.
Dr Karen Martin
Reviewed by Dr Karen Martin
Reviewed on 19.10.2023
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