Vitamin B12 deficiency

As the body stores vitamin B12, symptoms of deficiency can take up to four to five years of poor dietary intake or lack of intrinsic factor production to appear. Deficiency is more commonly linked to the inability to absorb the vitamin due to lack of intrinsic factor than to insufficient dietary intake.

Elderly people

Vitamin B12 deficiency is more common in the elderly than in younger people, with around 15 per cent of elderly men and women affected. This is usually because of decreased absorption due to reduced production of intrinsic factor or to a stomach disorder known as atrophic gastritis. Supplementation can prevent irreversible neurological damage if started early. Elderly people with vitamin B12 deficiency may show psychiatric or metabolic deficiency symptoms even before anemia is diagnosed. Screening for low vitamin B12 levels is necessary in elderly people with mental impairment, although it has also been found that deficiency states can still exist even when blood levels are higher than the traditional lower reference limit for vitamin B12. Patients who are most at risk of vitamin B12 deficiency include those with gastrointestinal disorders, autoimmune disorders, Type I diabetes mellitus and thyroid disorders, and those receiving long-term therapy with gastric acid inhibitors.

Vitamin B12 deficiencyBlood

Vitamin B12 deficiency causes pernicious anemia with symptoms of tiredness, pallor, lightheadedness, breathlessness, headache and irritability. Red blood cells become abnormally enlarged and reduced blood platelet formation causes poor clotting and bruising. A high intake of folic acid can prevent the red blood cell changes caused by vitamin B12 deficiency. It does not, however, prevent the nerve damage which may only become apparent in later stages and which may not be reversible. Strict vegetarians, whose folic acid intakes are high while their vitamin B12 intakes are low, may be at particular risk of nerve damage.

Immune system

Vitamin B12 deficiency leads to reduced numbers of white blood cells which causes increased susceptibility to infection. Recent research has shown that elderly patients with low vitamin B12 levels have impaired antibody response to bacterial vaccine, even when there are no clinical signs of deficiency.

Brain and nervous system

Vitamin B12 deficiency eventually leads to a deterioration in mental functioning, to neurological damage and to a number of psychological disturbances including memory loss, disorientation, dementia, moodiness, confusion and delusions. Alzheimer's disease sufferers are often found to have low vitamin B12 levels, although it is unclear whether these are a contributing factor or a result of the disease.

Vitamin B12 deficiency leads to a loss of nerve-insulating myelin which begins at the peripheral nerves and eventually moves up to the spine causing decreased reflexes, abnormal gait, weakness, fatigue, poor vision and impaired touch or pain sensation. Other signs include tingling or loss of sensation and weakness in hands and feet, and diminished sensitivity to vibration and position sense.

Gastrointestinal system

Vitamin B12 deficiency causes poor cell formation in the digestive tract and leads to nausea, vomiting, loss of appetite, poor absorption of food, soreness of the mouth and tongue, and diarrhea.

Heart disease

Vitamin B12 deficiency may lead to increased levels of an amino acid called homocysteine, which has been linked to an increased risk of heart disease.

Other symptoms

Vitamin B12 is involved in production of the genetic material of the cell and deficiency may cause defective production which could lead to cancer. A 1997 Australian study found that low levels of vitamin B12 could contribute to chromosome damage in white blood cells. Low levels of Vitamin B12 may also contribute to diabetic neuropathy, poor vision, recurrent yeast infections and infertility. Vitamin B12 affects bone cells, and deficiency may be risk factor for osteoporosis.

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Vitamin B12
Vitamin B12 health
Vitamin B12 absorption
Vitamin B12 deficiency
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Vitamin B12 recommended daily
Vitamin B12 supplements
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Other Vitamins:

Vitamin A
Beta carotene
Vitamin B6
Vitamin B12
Pantothenic acid
Vitamin C
Vitamin D
Vitamin E
Vitamin K