Vitamin B12

In the late 1800's, researchers found that a deadly disease of the red blood cells called pernicious anemia responded well to adding a pound of liver a day to the patient's diet. In the late 1940's, Vitamin B-12 (also known as cobalamin) was identified as the important factor in liver that positively affected the disease. Though liver is still a good source of the vitamin, it is commonly available by tablet or injection.

Vitamin B-12 is found in animal foods. It is necessary for processing carbohydrates, protein, and fats in the body. This important water-soluble vitamin also affects the growth and repair of all the cells, particularly nerve cells. As food passes through the system, the stomach secretes a special digestive hormone that increases the absorption of Vitamin B-12 in the small intestine. Unlike other water-soluble vitamins, this vitamin is stored in the body tissues, so a deficiency can take years to appear.

Many physicians recommend Vitamin B-12 injections, but there is a great deal of evidence that oral dosage is just as effective, even in cases of pernicious anemia.

Vitamin B-12 is an important factor in a number of body functions. It plays a role in the activation of amino acids during protein formation. In combination with folic acid, it is necessary for the syntheses of DNA and for maintaining the myelin sheath that surrounds nerve cells and facilitates the signals along the neurotransmitters.

A Vitamin B-12 deficiency can result from an inadequate diet, disease, or a lack of intrinsic factor in the small intestine necessary for absorption of the vitamin. A mild deficiency of Vitamin B-12 is very common. Symptoms range from lethargy and forgetfulness, to that too tired to get out of bed in the morning feeling. Severe deficiencies contribute to many chronic illnesses and can result in impaired nerve function or even permanent nerve damage.

Vitamin B-12 levels may decline with age and studies have found deficiencies in up to 40% of persons over 65. Deficiency in this vitamin among the elderly is thought to be a significant factor in mental impairment and depression. The symptoms can mimic Alzheimer's disease and a sustained vitamin deficiency, may lead to irreversible mental impairment. Vitamin B-12 has been embraced as a potential protector against the onset of Alzheimer's disease by its ability to increase the production of acetylcholine and normalize neurotransmissions in the brain. While Vitamin B-12 deficiency is not believed to be the primary cause of this disease, Alzheimer's patients have been shown to have low levels of the vitamin. Aluminum, targeted as an instigator of Alzheimer's, can reduce the efficacy of Vitamin B-12.

Vitamin B-12, along with folic acid, is an important factor in preventing certain birth defects. Vitamin B-12, folic acid, and Vitamin B-6 act together to lessen the risk of heart disease by regulating and reducing blood levels of the amino acid, homocysteine. At high levels, homocysteine causes atherosclerosis.

Vitamin B-12 supplements have also been found to be an effective therapy for "child"hood asthma, depression, diabetic neuropathy, and low sperm count and motility. There is some indication that 35% of people who are HIV positive are also deficient in the vitamin. Whether this deficiency is the result of malabsorption or interactions with the drug AZT is not clear. What is certain, though, is that deficiency of Vitamin B-12 and other nutrients will facilitate and worsen the progression towards AIDS. In laboratory studies, Vitamin B-12 has been shown to halt the replication of HIV. Vitamin B-12 currently stands as a assuring and important addition to the treatment for this disease.

REFFERENCES:

1 In 1934, two Harvard physicians, Dr. George Richards Minot and William Parry Murphy, were awarded the Nobel prize for discovering this treatment for pernicious anemia.

2 Berlin H, Berlin R, and Brante G, Oral treatment of pernicious anemia with high doses of vitamin B-12 without intrinsic factor. Acta Med Scand 184:247, 248, 1968.

3 Van Goor, et al. Review, Cobalamin deficiency and mental impairment in elderly people. Age Aging 24, 536-542, 1995.

4 Ubbink JB, et al., Vitamin B-12, vitamin B-6, and folate nutritional status in men with hyperhomocysteinemia. Am J Clin Nutr 57, 47-53, 1993; Ubbink JB, van der Merwe WJ, and Delport R, Hyperhomocysteinemia and the response to vitamin supplementation. Clin Invest 71, 993-998, 1993; and Nilsson K, et.al., Plasma homocysteine in relationship to serum cobalamin and blood folate in a psychogeriatric population. Eur J Clin Invest 24, 600-606, 1994.

5 Weinberg JB, et al., Inhibition of productive human immunodeficiency virus-1 infection by cobalamine. Blood86,1281-1287, 1995.

VITAMIN B-12: SOURCES

• Beef
• Beef liver
• Blue cheese
• Clams
• Eggs
• Flounder
• Herring
• Kidney
• Liver
• Liverwurst
• Mackerel
• Milk
• Milk products
• Sardines
• Snapper
• Swiss cheese

NOTE: Vitamin B-12 is not found in vegetables.

Available as:

• Oral and injectable forms. Oral forms are used only as diet supplement. Only people with portions of the gastrointestinal tract removed surgically or those with pernicious anemia require injections.
• Tablets: Take with meals or 1 to 1-1/2 hours after meals unless otherwise directed by your doctor.
• Extended-release capsules or tablets: Swallow whole with full glass of liquid. Don't chew or crush. Take with or immediately after food to decrease stomach irritation.
• Injectable forms are administered by doctor or nurse.
• A constituent of many multivitamin/mineral preparations.
• Cyanocobalamin is the most common form of B-12. It must be converted into a form that the body can use.
• Methylcobalamin and adenosylcobalamin are the two active forms of this vitamin. Methylcobalamin, active immediately upon absorption, is the only form available as a tablet and is considered the best of the three.

VITAMIN B-12: PROVEN BENEFITS

• Promotes normal growth and development.
• Treats some types of nerve damage.
• Treats pernicious anemia.
• Treats and prevents Vitamin B-12 deficiencies in people who have had a portion of the gastrointestinal tract surgically removed.
• Prevents Vitamin B-12 deficiency in vegan vegetarians and persons with absorption diseases.
• Plays an important role in homocysteine and energy metabolism, and immune and nerve function.

What this vitamin does:

• Acts as co-enzyme for normal DNA synthesis.
• Promotes normal fat and carbohydrate metabolism and protein syntheses.
• Promotes growth, cell development, blood-cell development, manufacture of covering to nerve cells, maintenance of normal function of nervous system.

VITAMIN B-12: UNPROVED SPECULATED BENEFITS

• Helps mental and nervous disorders.
• Improves resistance to infection and disease.
• Increases appetite.
• Promotes growth of someone who has smaller-than-average stature.
• Improves memory and the ability to learn.
• Increases energy.

VITAMIN B-12: SPECIAL CONSIDERATIONS

• Strict vegetarians.
• Anyone with inadequate caloric or nutritional dietary intake or increased nutritional requirements.
• Those who abuse alcohol or other drugs.
• People with a chronic wasting illness, excess stress for long periods or who have recently undergone surgery.
• Those with a portion of the gastrointestinal tract surgically removed.
• People with recent severe burns or injuries.

Miscellaneous information:

• There is a very low incidence of toxicity of Vitamin B-12, even with large amounts up to 1,000 mcg/day.
• B-12 contains a high cobalt content.

VITAMIN B-12: DEFICIENCY SYMPTOMS

• Impaired brain and nervous system function; demylination of nerve fibers in Central Nervous System
• Diarrhea
• Smooth, beefy red tongue
• Tingling and burning sensations
• Impaired mental functioning similar to Alzheimer's disease
• Inability to replicate cells lining mouth and gastrointestinal tract
• False positive pap smear
• Pernicious anemia, with the following symptoms:
• Fatigue, profound weakness, especially in arms and legs, sore tongue, nausea, appetite loss, weight loss, bleeding gums, numbness and tingling in hands and feet, difficulty maintaining balance, pale lips, pale tongue, pale gums, yellow eyes and skin, shortness of breath, depression, confusion and dementia, headache, poor memory.

VITAMIN B-12: UNPROVED SPECULATED SYMPTOMS

• Aging
• Allergies
• Eye problems
• Slow growth
• Skin problems
• Easy fatigue
• Mental symptoms
• Sterility
• Thyroid disorders
• Menstrual disorders
• Delusions and hallucinations1

1 From Griffith HW, Vitamins, Minerals, and Supplements.

VITAMIN B-12: LAB TESTS TO DETECT DEFICIENCY

• Serum Vitamin B-12, a radioactive study usually performed with serum-folic-acid test, called the Schilling Test (serum level unreliable unless levels are abnormally low)
• Reticulocyte count
• Measure methylmalonic acid in urine
• Plasma homocysteine level
• Elevated mean corpuscular volume; lymphatic growth response; successful therapeutic trial of intramuscular injections.

VITAMIN B-12: OPTIMAL LEVELS

10-100 mcg. for adults

VITAMIN B-12: MINIMUM DOSAGE

Recommended Dietary Allowance (RDA):

Estimate of adequate daily intake by the Food and Nutrition Board of the National Research Council, 1989. Recommended dosage for detected deficiency states is 2000 mcg daily for one month, then 1000 mcg daily. Vegetarians are advised to obtain at least 100 mcg of B-12 each day.

Age RDA

0-6 months 0.3mcg

6-12 months 0.5mcg

1-3 years 0.7mcg

4-6 years 1.0mcg

7-10 years 1.4mcg

11+ years 2.0mcg

Pregnant +2.2mcg

Lactating +2.6mcg

VITAMIN B-12: WARNINGS AND PRECAUTIONS

Don't take if you:

• Are allergic to B-12 given by injection. Allergy to injections produces itching, redness, swelling and rarely blood-pressure drop with loss of consciousness.
• Have Leber's disease.
• Consult your doctor if you have:
• Gout.

Over age 55:

• No problems expected.

Pregnancy:

• No problems expected.

Breast-feeding:

• No problems expected.

Effect on lab tests:

• Tests for serum potassium may show precipitous drop (hypokalemia) during 48 hours after beginning treatment for anemia.

Storage:

• Store in cool, dry place away from direct light, but don't freeze. Liquid forms should be refrigerated.
• Store safely out of reach of "child"ren.
• Don't store in bathroom medicine cabinet. Heat and moisture may change action of vitamin.

Others:

The injectable form is the only effective form to treat pernicious anemia or people with portions of the gastrointestinal tract surgically removed. These individuals do not absorb oral forms.

VITAMIN B-12: OVERDOSE/TOXICITY

Signs and symptoms:

• For accidental overdosage (such as "child" taking entire bottle): Call your nearest poison control center.

What to do:

• For symptoms of overdosage: Discontinue vitamin, and consult doctor. Also see ADVERSE REACTIONS OR SIDE EFFECTS.1

1 From Griffith HW, Vitamins, Minerals, and Supplements.

VITAMIN B-12: ADVERSE REACTIONS OR SIDE EFFECTS

Reaction or effect What to do

Diarrhea (rare) Discontinue. Call doctor immediately.

Itching skin after injections (rare) Seek emergency treatment.

VITAMIN B-12: INTERACTION WITH OTHER SUBSTANCES

• Aminosalicylates reduce absorption of Vitamin B-12.
• Antibiotics may cause false-low test results for Vitamin B-12.
• Ascorbic acid (Vitamin C): Large doses may destroy Vitamin B-12. Separate doses by at least 1 hour.
• Chloramphenicol may prevent therapeutic response when Vitamin B-12 is used to treat anemia.
• Cholestyramine reduces absorption of Vitamin B-12.
• Colchicine reduces absorption of Vitamin B-12.
• Folic acid: Large doses decrease Vitamin B-12 concentrations in blood.
• Melatonin: Low B-12 levels may result in low melatonin secretion.
• Neomycin (oral forms only) reduces absorption of Vitamin B-12.
• Potassium in extended-release forms reduces absorption of Vitamin B-12. May increase need for Vitamin B-12.
• Tobacco decreases absorption. Smokers may require supplemental Vitamin B-12.
• Alcohol in excessive amounts for long periods may lead to Vitamin B-12 deficiency.

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