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The daily recommended intake of vitamin B12 is less than 3 micrograms, that is less than 3 millionths of a gram. The ink in the period at the end of this sentence (if you were to print this) probably weighs about 3 micrograms. This may seem like a tiny amount but it contains billions of molecules of B12 needed to help the body function properly.
It is necessary for the production of red blood cells (which carry oxygen throughout the body) and to help cells metabolize carbohydrates, proteins, and fats. It also plays a role in the proper development of nerve cells.
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The body does not make vitamin B12 so it must get it from foods or supplements. A deficiency in B12 can be caused by not getting enough of the vitamin or by some other factor.
• Diet lacking foods with B12.
• Surgery removing parts of the stomach (like gastric bypass) or the last part of the small intestine (ileum).
• Digestive problems, such as Crohn's disease, celiac disease, or parasites.
• Lack of a substance called intrinsic factor (IF). B12 is dependent upon this substance to make its way from the gastrointestinal tract to the rest of the body.
• Insufficient secretion of stomach acid. Stomach acid is needed to release B12 from the proteins in the food.
• Vitamin B6 deficiency. B6 is necessary for the proper absorption of B12.
• Vitamin E deficiency. E is needed to convert B12 from its non-active form into its biologically active form.
• Long-term use of antacids or ulcer medications.
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Signs of B12 Deficiency
- weight loss
- fast heart rate
- heart palpitations
Signs over a long period of time include:
- poor sense of balance
- tingling or numbness in the fingers and toes
- memory problems
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Vitamin B12 is unique among other vitamins (and minerals) because it is found almost exclusively in meats and animal products. Excellent sources of food containing B12 are calf's liver and snapper. Very good sources include beef, venison, salmon, and shrimp. Good sources include eggs, milk, and yogurt.
It is controversial whether vegans (who eat a strict vegetarian diet) receive enough B12 through diet alone. Sea plants, tofu, miso, tamari, shoyu, and tempeh are some non-animal products that may or may not contain adequate amounts of B12. Reliable nutrient analyses are normally not provided. To be on the safe side, some suggest vegans should eat foods fortified with B12 or take a vitamin B12 supplement.
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To prevent signs of B12 deficiency, the following daily amounts are recommended:
infants (0-6 months) 0.4 µ (micrograms)
infants (7-12 months) 0.5 µ
children (1-3 years) 0.9 µ
children (4-8 years) 1.2 µ
children (9-13 years) 1.8 µ
adolescents (14-18 years) 2.4 µ
adults (19+) 2.4 µ
pregnancy (any age) 2.6 µ
lactation (any age) 2.8 µ
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WebMD: Vitamin B12 Deficiency Anemia - http://www.webmd.com/a-to-z-guides/vitamin-b12-deficiency-anemia-topic-overview
WHFoods: Vitamin B12 - http://www.whfoods.com/genpage.php?tname=nutrient&dbid=107
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Image courtesy of the National Library of Medicine (NLM)