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DESCRIPTION
Vitamin B-12, also called cobalamin, is important to good health and is needed to prevent anemia, maintain healthy nerve cells and red blood cells, and is also needed to make DNA, the genetic material in all cells.
Vitamin B-12 aids folic acid in regulating the formation of red blood cells, and helps in the utilization of iron. This vitamin is also required for proper digestion, absorption of foods, the synthesis of protein, and the metabolism of carbohydrates and fats. It aids in cell formation and cellular longevity. In addition, vitamin B-12 prevents nerve damage, maintains fertility, and promotes normal growth and development by maintaining the fatty sheaths that cover and protect nerve endings. Vitamin B-12 is linked to the production of acetylcholine, a neurotransmitter that assists memory and learning.
A vitamin B-12 deficiency can be caused by malabsorption, which is most common in elderly people and in those with digestive disorders. Deficiency can cause abnormal gait, chronic fatigue, constipation, depression, digestive disorders, dizziness, drowsiness, enlargement of the liver, eye disorders, hallucinations, headaches, inflammation of the tongue, irritability, labored breathing, memory loss, moodiness, nervousness, neurological damage, palpitations, pernicious anemia, ringing in the ears, and spinal cord degeneration. Strict vegetarians (vegans) must remember that they require vitamin B-12 supplementation, as this vitamin is found almost exclusively in animal tissues. Although people adopting a strictly vegetarian diet may not see signs of deficiency for some time - the body can store up to 5 years' worth of vitamin B-12 - signs will eventually develop.
SOURCES OF VITAMIN B-12
Vitamin B-12 is bound to the protein in food. Hydrochloric acid in the stomach releases B-12 from protein during digestion. Once released, B-12 combines with a substance called intrinsic factor (IF) before it is absorbed into the bloodstream.
RECOMMENDED DIETARY ALLOWANCE FOR VITAMIN B-12 IN ADULTS
The Recommended Dietary Allowance (RDA) is the average daily dietary intake level that is sufficient to meet the nutrient requirements of nearly all (97 to 98 percent) healthy individuals in each life-stage and gender group. The 1998 RDAs for vitamin B-12 (in micrograms) for adults are:
LIFE-STAGE MEN WOMEN PREGNANCY LACTATION Ages 19+ 2.4 mcg 2.4 mcg All ages 2.6 mcg 2.8 mcg
Results of two national surveys, the National Health and Nutrition Examination Survey (NHANES III-1988-91) and the Continuing Survey of Food Intakes by Individuals (CSFII 1994-96) found that most adult men and women consume recommended amounts of vitamin B-12.
FOOD SOURCES OF VITAMIN B-12
Vitamin B-12 is naturally found in animal foods including fish, milk and milk products, eggs, meat and poultry. Fortified breakfast cereals are an excellent source of vitamin B-12 and a particularly valuable source for vegetarians.
The largest amounts of vitamin B-12 are found in Brewer's Yeast, clams, eggs, herring, kidney, liver, mackerel, milk and dairy products, and seafood. Vitamin B-12 is not found in many vegetables; it is available only from sea vegetables, such as Dulse, Kelp, kombu, and nori, and soybeans and soy products. It is also present in the herbs Alfalfa, Bladderwrack, and Hops.
The table of selected food sources of vitamin B-12 suggests dietary sources of vitamin B-12.
As the 2000 Dietary Guidelines for Americans state, "Different foods contain different nutrients and other healthful substances. No single food can supply all the nutrients in the amounts you need". As the following table indicates, vitamin B-12 is found naturally in animal foods. It is also found in fortified foods such as fortified breakfast cereals. If you want more information about building a healthful diet, refer to Dietary Guidelines for Americans and the Food Guide Pyramid.
TABLE OF FOOD SOURCES OF VITAMIN B-12
FOOD MICROGRAMS (mcg) %DV* Beef liver, cooked, 3 oz 60.0 1000 Fortified breakfast cereals, (100% fortified), 3/4 cup 6.0 100 Trout, rainbow, cooked, 3 oz 5.3 90 Salmon, sockeye, cooked, 3 oz 4.9 80 Beef, cooked, 3 oz 2.1 35 Fortified breakfast cereals (25% fortified), 3/4 cup 1.5 25 Haddock, cooked, 3 oz 1.2 20 Clams, breaded and fried, 3/4 cup 1.1 20 Oysters, breaded and fried, 6 pieces 1.0 15 Tuna, white, canned in water, 3 oz 0.9 15 Milk, 1 cup 0.9 15 Yogurt, 8 oz 0.9 15 Pork, cooked, 3 oz 0.6 10 Egg, 1 large 0.5 8 American Cheese, 1 oz 0.4 6 Chicken, cooked, 3 oz 0.3 6 Cheddar cheese, 1 oz 0.2 4 Mozzarella cheese, 1 oz 0.2 4
* DV = Daily Value. DVs are reference numbers based on the Recommended Dietary Allowance (RDA). They were developed to help consumers determine if a food contains a lot or a little of a specific nutrient. The DV for vitamin B-12 is 6.0 micrograms (mcg). The percent DV (%DV) listed on the nutrition facts panel of food labels tells adults what percentage of the DV is provided by one serving. Percent DVs are based on a 2,000 calorie diet. Your Daily Values may be higher or lower depending on your calorie needs. Foods that provide lower percentages of the DV also contribute to a healthful diet.
REFERENCES
National Institutes of Health (NIH), Bethesda, MD, in conjunction with the Office of Dietary Supplements (ODS) in the Office of the Director of NIH.
VITAMIN B-12 DEFICIENCY
Diets of most adult Americans provide recommended intakes of vitamin B-12, but deficiency may still occur as a result of an inability to absorb B-12 from food. It can also occur in individuals with dietary patterns that exclude animal or fortified foods. As a general rule, most individuals who develop a vitamin B-12 deficiency have an underlying stomach or intestinal disorder that limits the absorption of vitamin B-12. Sometimes the only symptom of these intestinal disorders is anemia resulting from B-12 deficiency.
Characteristic signs of B-12 deficiency include fatigue, weakness, nausea, constipation, flatulence (gas), loss of appetite, and weight loss. Deficiency also can lead to neurological changes such as numbness and tingling in the hands and feet. Additional symptoms of B-12 deficiency are difficulty in maintaining balance, depression, confusion, poor memory, and soreness of the mouth or tongue. Some of these symptoms can also result from a variety of medical conditions other than vitamin B-12 deficiency. It is important to have a healthcare provider evaluate these symptoms so that appropriate medical care can be given.
PERNICIOUS ANEMIA
Pernicious anemia is a form of anemia that occurs when there is an absence of intrinsic factor, a substance normally present in the stomach. Vitamin B-12 binds with intrinsic factor before it is absorbed and used by your body. An absence of intrinsic factor prevents normal absorption of B-12 and results in pernicious anemia.
Anyone with pernicious anemia usually needs intramuscular (IM) injections (shots) of vitamin B-12. It is very important to remember that pernicious anemia is a chronic condition that should be monitored by a health care provider. Anyone with pernicious anemia has to take lifelong supplemental vitamin B-12.
MoonDragon's Anemia Information Index
GASTROINTESTINAL DISORDERS
Individuals with stomach and small intestinal disorders may not absorb enough vitamin B-12 from food to maintain healthy body stores. Sprue and celiac disease are intestinal disorders by intolerance to protein in wheat and wheat products. Regional enteritis, localized inflammation of the stomach or small intestine, also results in generalized malabsorption of vitamin B-12. Excess bacteria in the stomach and small intestine also can decrease vitamin B-12 absorption.
Surgical procedures of the gastrointestinal tract such as surgery to remove all or part of the stomach often result in a loss of cells that secrete stomach acid and intrinsic factor. Surgical removal of the distal ileum, a section of the intestines, also can result in the inability to absorb B-12. Anyone who has had either of these surgeries usually requires lifelong supplemental B-12 to prevent a deficiency.
VITAMIN B-12 & OLDER ADULTS
Vitamin B-12 must be separated from protein in food before it can bind with intrinsic factor and be absorbed by your body. Bacterial overgrowth in the stomach and/or atrophic gastritis, an inflammation of the stomach, contribute to vitamin B-12 deficiency in adults by limiting secretions of stomach acid needed to separate vitamin B-12 from protein in food. Adults 50 years of age and older with these conditions are able to absorb the B-12 in fortified foods and dietary supplements. Health care professionals may advise adults over the age of 50 to get their vitamin B-12 from a dietary supplement or from foods fortified with vitamin B-12 because 10 to 30 percent of older people may be unable to absorb vitamin B-12 in food.
VITAMIN B-12 & VEGETARIANS
Vegetarians who do not eat meats, fish, eggs, milk or milk products, or B-12 fortified foods consume no vitamin B-12 and are at high risk of developing a deficiency of vitamin B-12. When adults adopt a vegetarian diet, deficiency symptoms can be slow to appear because it usually takes years to deplete normal body stores of B-12. However, severe symptoms of B-12 deficiency, most often featuring poor neurological development, can show up quickly in children and breast-fed infants of women who follow a strict vegetarian diet.
Fortified cereals are one of the few plant food sources of vitamin B-12, and are an important dietary source of B-12 for vegetarians who consume no eggs, milk or milk products. Vegetarian adults who do not consume plant foods fortified with vitamin B-12 need to consider taking a B-12-containing supplement. Vegetarian mothers should consult with a pediatrician regarding appropriate vitamin B-12 supplementation for their infants and children.
VITAMIN B-12, HOMOCYSTEINE & HEART DISEASE
A deficiency of vitamin B-12, folate, or vitamin B-6 may increase your blood level of homocysteine, an amino acid normally found in your blood. There is evidence that an elevated blood level of homocysteine is an independent risk factor for heart disease and stroke. The evidence suggests that high levels of homocysteine may damage coronary arteries or make it easier for blood clotting cells called platelets to clump together and form a clot. However, there is currently no evidence available to suggest that lowering homocysteine level with vitamins will actually reduce your risk of heart disease. Clinical intervention trials are needed to determine whether supplementation with vitamin B-12, folic acid, or vitamin B-6 can help protect you against developing coronary heart disease.
COMMENTS
MEDICATIONS & DIETARY SUPPLEMENT CONCERNS
Anti-gout medications, anticoagulant drugs, and potassium supplements may block the absorption of vitamin B-12 from the digestive tract. Vegetarians need supplements of vitamin B-12 because it is found mostly in animal sources.
Caution: Folic acid may mask signs of vitamin B-12 deficiency.
Folic acid can correct the anemia that is caused by vitamin B-12 deficiency. Unfortunately, folic acid will not correct the underlying B-12 deficiency. Permanent nerve damage can occur if vitamin B-12 deficiency is not treated. Folic acid intake from food and supplements should not exceed 1,000 micrograms (mcg) daily because large amounts of folic acid can hide the damaging effects of vitamin B-12 deficiency. Adults older than 50 years are advised to consult with their healthcare provider about the advisability of taking folic acid without also taking a vitamin B-12 supplement.
VITAMIN B-12 TOXICITY
Vitamin B-12 has a very low potential for toxicity. The Institute of Medicine states that "no adverse effects have been associated with excess vitamin B-12 intake from food and supplements in healthy individuals." The Institute recommends that adults over 50 years of age get most of their vitamin B-12 from supplements or fortified food because of the high incidence of impaired absorption of B-12 from unfortified foods in this population.
VITAMIN B-12 SUPPLEMENTS & PRODUCTS
Instant Energy B-12 Packets, NOW Foods, 2,000 mcg, 75 Packets
NOW Vitamin B-12 Instant Energy is the perfect way to keep alert and energized, regardless of the situation. These convenient, fast-acting packets are perfect when traveling or for convenience.
Liquid Vitamin B-12 Energy, NOW Foods, (2) 1 fl. oz. dropper bottles
Vitamin B-12 is an essential nutrient that is involved in the metabolism of amino acids and Liquid Vitamin B-12 from NOW Foods is synergistically blended to insure complete utilization.
Ola Loa Children's Multi-Vitamin Drink Mix, Cran Raspberry, 30 Packets
Better your kids health by introducing them to this Child Multi-Vitamin based upon the most up-to-date studies on nutrition and child development and is 100% all-natural.
Twinlab, B-12 Dots, 500 mcg, 100 count
Micro-sublingual vitamin B-12 (cyanocobalamin) tablets. Cherry flavored. B-12 (Cobalamin) belongs to the B-complex family and may help with mental disorders, fatigue, debilitated states, pernicious anemia, insomnia, depression, stress, bursitis and multiple sclerosis. B-12 Dots are specially formulated tiny sublingual B-12 tablets. One dot (sublingual tablet) contains 500mcg of Vitamin B-12.
Twinlab, B-12 Dots, 500 mcg, 250 Dots
Vitamin B-12 functions in the body in the form of two coenzymes.
Ultimate B Vitamin B-12 Complex Formula, Nature's Secret, 60 Tabs
Superbly formulated, Ultimate B, vitamin B Complex Formula, is a synergistic blend of herbs, superfoods, and enzymes made of 33% food ingredients for easy absorption.
Ultra B-12, NOW Foods, 4 oz.
Vitamin B-12 is necessary for the maintenance of a healthy nervous system and for the metabolic utilization of fats and proteins.
Vitamin B-12, California Natural, 1,000 mcg, 60 Tabs
B-12 is an essential nutrient that functions as a coenzyme. Cobalmin is critical to maintain healthy nerves and nerve function. Vitamin B-12 is also critical to maintain healthy red blood cells and homocysteine levels.
Vitamin B-12 Complex Liquid, NOW Foods, 2 fl. oz.
Vitamin B-12 Helps to maintain a healthy nervous system, and helps in the prevention of pernicious anemia. Folic Acid should be taken by all females of child bearing age to help prevent neuro-tube birth defects. Folic acid is also linked to heart health.
Vitamin B-12 / Cyanocobalamin, Nature's Way, 2,000 mcg, 100 Sublingual Lozenges
Nature's Way Sublingual Vitamin B-12 is 100% natural from cyanocobalamin concentrate.
Vitamin B-12 LipoSpray, NOW Foods, 2 oz.
This combination of key B-vitamins may aid the body's regulation of homocysteine, a potentially harmful byproduct of protein metabolism.
Herbal Remedies: Vitamin B Complex & Vitamin B Supplements & Products
Herbal Remedies: Vitamin B-12 Information
Herbal Remedies: Vitamin B-12 / Cobalamin / Cyanacobalamin / Hydroxycobalamin / Denosylcobalamin / Methylcobalamin Supplements & Products
HELPFUL PRODUCTS & FURTHER EDUCATION
Prescription for Nutritional Healing: The A-To-Z Guide To Supplements
-- by Phyllis A. Balch, James F. Balch - 2nd Edition
Prescription for Nutritional Healing: The A-To-Z Guide To Supplements
-- by Phyllis A. Balch, James F. Balch - 4th Edition
Prescription for Herbal Healing: The A-To-Z Reference To Common Disorders
-- by Phyllis A. Balch
The Complete Guide to Natural Healing
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HERBS, OILS, & SUPPLIES
Mountain Rose Bulk Herbs
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