Vitamin B-12 or cobalamin, also known as methylcobalamin or adenosylcobalamin, is found only in foods of animal origin. In the body, B-12 is important for DNA synthesis, methionine metabolism, energy production and neurological function. To absorb B-12, adequate hydrochloric acid, the acid in your stomach, and intrinsic factor, an enzyme made in the stomach, is required. Certain individuals lack this enzyme and may suffer from pernicious anemia and may need to speak with their doctor about B-12 injections.
Sublingual B-12 Recommendations
Optimal levels for B-12 range from 200 to 900 pg/mL, while deficiency levels are considered below 200 pg/mL. According to the Office of Dietary Supplements, sublingual drops of B-12 are not better absorbed compared to supplements or pills taken orally. However, sublingual drops are available in high dosage amounts from 1,000 to 5,000 mcg, which may help to correct B-12 deficiency quickly. In 2003, "The British Journal of Clinical Pharmacology" indicated that 500 mcg of sublingual B-12 helped in correcting a B-12 deficiency.
RDA Recommendations
The recommended dietary allowance, or RDA, of B-12 is 2.4 mcg per day with increased amounts needed during pregnancy and while breast-feeding. Three ounces of steamed clams supplies 84 mcg, while 3 oz. of steamed crab provides 8.8 mcg per day. Other sources in smaller amounts include beef, salmon, chicken, turkey, eggs, milk or cheese. The Linus Pauling Institute notes that a varied diet should provide enough B-12 to prevent deficiency in healthy adults 50 years of age or younger. However, strict vegans or vegetarians, women planning to become pregnant, or older adults should aim for a daily intake of 6 to 30 mcg a day. Older adults over the age of 50, who may suffer from B-12 deficiency or malabsorption, may require an increased amount via a supplemental form.
B-12 Deficiencies
As B-12 is only found in animal products, vegans, older adults who do not produce enough stomach acid, babies who were breast-fed by B-12 deficient mothers, people with malabsorption or digestive disorders such as celiac disease or Crohn's disease, individuals with pernicious anemia, or those who have had gastrointestinal disorders may be at risk for a B-12 deficiency.
General symptoms of a B-12 deficiency include weakness, fatigue, weight loss, loss of appetite, shortness of breath, memory loss, megaloblastic anemia, tingling and/or numbness in the hands and feet, confusion, poor memory, difficulty maintaining balance, depression and dementia.
Warnings
Vitamin B-12 has not been shown to have toxic effect in high amounts. The Institute of Medicine states "no adverse effects have been associated with excess vitamin B-12 intake from food and supplements in healthy individuals." B-12 can interfere with medications, including proton pump inhibitors, Metformin, H2 receptor antagonists and certain antibiotics.
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