Vitamins>Vitamin B12

  • Vitamin B12 Prevents anaemia
  • It Promotes growth
  • It maintains healthy nervous system
  • It relieves irritability

How it works

Vitamin B12 is crucial for the recycling of certain key enzymes in the body, which help to maintain the health of nerves and other cells. It is needed to create the "myelin sheath", a covering around nerves that allows for the quick transmission of nerve impulses. B12 is also needed for growth when we are young, is involved in controlling the appetite, and is necessary for the production of healthy red blood cells.

Absorption helpers The mineral calcium and other B vitamins, as well as vitamins A, C, and E, all work together to improve B12 absorption in the body.

Absorption inhibitors The drug Metformin (used to treat non-insulin dependent diabetics), Cholestyramine (used to treat high cholesterol), and the oral contraceptive pill all reduce B12 absorption. Sleeping pills and alcohol have a similar effect.


Taking B12 supplements

The adult RDA for vitamin B12 (1mcg) a day is equivalent to one 50g serving of beef. Intakes of vitamin B12 can be sustained by regularly eating foods such as meat, poultry, fish, eggs, dairy foods, fortified breakfast cereals, and fortified spread (yeast extract e.g., marmite).

Cyanocobalamin is the best form of vitamin B12 supplement to take. While only 1mcg is needed daily in order to prevent deficiency of B12 in the body, the optimum amount suggested for this vitamin is 2.5-25mcg daily for children and 5-10mcg for adults.

Combining supplements Vitamin B12 works well in conjunction with folic acid and is best taken as a B-complex supplement with food.

Precautions No side effects of vitamin B12 are known at present. The safe upper level for the vitamin has been established at 3,000mcg a day; no long- or short-term toxicity problems have yet been established for this amount.



Why take this supplement?

With the exception of fermented soy, called tempeh, vitamin B12 is not found in plants but is added to foods as a fortified ingredient. Strict vegetarians must take vitamin B12 to avoid deficiency, either as supplements or in fortified food. Pregnant and breastfeeding women may also benefit from supplements, along with people over 55 (the ability to absorb B12 declines with age). The following symptoms may also indicate a need for extra vitamin B12:

  • Fatigue
  • Poor hair condition
  • Eczema
  • Dermatitis
  • Sore tongue
  • Memory loss
  • Lack of concentration
  • Anaemia
  • Irritability
  • Anxiety or tension
  • Tender or sore muscles

Therapeutic uses

  • Improved mood Vitamin B12 appears to be indirectly important in the production of brain transmitters - such as the "feel good" substances serotonin and dopamine. As these chemicals are able to control our moods, sleep patterns, and other psychological functions, B12 supplements may improve low moods.
  • Fatigue Doctors now use vitamin B12 supplements and injections for a wide range of problems that affect energy levels.
  • Diabetes The nerve damage experienced by people who have diabetes is similar to the deficiency symptoms of B12. Some researchers believe that a disturbance in the B12 metabolism in diabetics might increase nerve damage, so supplements may be appropriate.
  • Poor vision It is suggested that poor vision resulting from low dietary intakes of B12 might be reversed by taking supplements of the vitamin.

Chemical names

  • Cobalamin


  • Tablets
  • Capsules

RDA for adults


Top sources of vitamin B12 mcg/100g of food

  • Lamb's liver 81mcg/100g
  • Liver pate7.2mcg/100g
  • Duck3mcg/100g
  • Pheasant2.5mcg/100g
  • Eggs2.5mcg/100g
  • Cod2.0mcg/100g
  • Beef2.0mcg/100g
  • Fortified breakfast cereals1.7mcg/100g
  • Yeast extract0.5mcg/100g

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