Manage mild deficiency with over-the-counter vitamin B12 supplements
If you follow a strict vegan diet, take a daily B12 supplement of at least 2.4 mcg
An abnormally low level of vitamin B12 (cobalamin) is a factor in many disorders.
The absorption of dietary vitamin B12 occurs in the small intestine and requires a secretion from the stomach known as intrinsic factor. If intrinsic factor is deficient, absorption of vitamin B12 is severely diminished. Vitamin B12 deficiency impairs the body’s ability to make blood, accelerates blood cell destruction, and damages the nervous system. The result is pernicious anemia (PA). In the classical definition, PA refers only to B12 deficiency anemia caused by a lack of intrinsic factor.
True pernicious anemia is probably an autoimmune disease. The immune system destroys cells in the stomach that secrete intrinsic factor. Many people with PA have both chronic inflammation of the stomach lining, called atrophic gastritis, and antibodies that fight their intrinsic factor-secreting cells.1
The term pernicious anemia is sometimes used colloquially to refer to any anemia caused by vitamin B12 deficiency. Vitamin B12 deficiency can be due to malabsorption of dietary B12 despite normal levels of intrinsic factor. For example, celiac disease and Crohn’s disease may cause B12 malabsorption, which can lead to anemia. Less common causes of B12 deficiency include gastrointestinal surgery, pancreatic disease, intestinal parasites, and certain drugs. Pregnancy, hyperthyroidism, and advanced stages of cancer may increase the body’s requirement for B12, sometimes leading to a deficiency state.
Low stomach acid , known as hypochlorhydria, interferes with the absorption of B12 from food but not from supplements. Aging is associated with a decrease in the normal secretion of stomach acid. As a result, some older people with normal levels of intrinsic factor and with no clear cause for malabsorption will become vitamin B12-deficient unless they take at least a few micrograms per day of vitamin B12 from supplements.
Caution: Pernicious anemia is a serious medical condition. When fatigue, often the first symptom of PA, is present, a qualified healthcare practitioner should be consulted. Symptoms of PA can be caused by other conditions, none of which would respond to vitamin B12 supplementation. Moreover, if true vitamin B12 deficiency exists, the cause—lack of intrinsic factor, general malabsorption conditions, lack of stomach acidity, or dietary deficiency—must also be properly diagnosed by examination and blood tests before the appropriate treatment can be determined.
Symptoms of severe vitamin B12 deficiency (regardless of the cause) may include burning of the tongue, fatigue, weakness, loss of appetite, intermittent constipation and diarrhea, abdominal pain, weight loss, menstrual symptoms, psychological symptoms, and nervous system problems, such as numbness and tingling in the feet and hands. Most symptoms can occur before the deficiency is severe enough to cause anemia. Healthcare professionals have a series of laboratory tests that can determine B12 deficiency at earlier stages that are not accompanied by anemia.
|Eat foods high in vitamin B12||
Even small amounts of meat, poultry, fish, eggs, and dairy products supply sufficient amounts of vitamin B12 for healthy people.
Vitamin B12 is found in significant amounts only in animal protein foods—meat and poultry, fish, eggs, and dairy products. Even small amounts of these foods supply sufficient amounts of vitamin B12 to provide enough for healthy people.
|Add B12 to your vegan diet||
If you follow a strict vegan diet, take a daily B12 supplement of at least 2.4 mcg.
Except for vegans (vegetarians who also abstain from eggs, dairy, and other animal products), virtually no one in North America has a diet deficient in vitamin B12. Those who avoid animal protein foods can easily take vitamin B12 supplements instead. Strict vegans generally develop a dietary deficiency of vitamin B12, but it is often many years before a deficiency becomes severe enough to cause symptoms or to be diagnosed. Doctors recommend that all vegans supplement with vitamin B12.
|Take supplements if you have low stomach acid or malabsorption||
People who have a vitamin B12 deficiency due to malabsorption or low stomach acid need to depend on high amounts of vitamin B12 from supplements and not the smaller amounts found in food.
People who lack intrinsic factor or have a malabsorption condition need to depend on high amounts of vitamin B12 from supplements and not the lower amounts found in food. Similarly, older people with a vitamin B12 deficiency due to a lack of stomach acid, but not a lack of intrinsic factor, cannot depend on food-based vitamin B12.
Our proprietary “Star-Rating” system was developed to help you easily understand the amount of scientific support behind each supplement in relation to a specific health condition. While there is no way to predict whether a vitamin, mineral, or herb will successfully treat or prevent associated health conditions, our unique ratings tell you how well these supplements are understood by the medical community, and whether studies have found them to be effective for other people.
For over a decade, our team has combed through thousands of research articles published in reputable journals. To help you make educated decisions, and to better understand controversial or confusing supplements, our medical experts have digested the science into these three easy-to-follow ratings. We hope this provides you with a helpful resource to make informed decisions towards your health and well-being.
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Consult a qualified healthcare practitioner
Vitamin B12, often given as an initial injection and then orally, may correct a deficiency.
Normally, only 3 to 4 mcg per day of vitamin B12 is required to prevent dietary deficiency. If gastrointestinal function is normal, even these small amounts of vitamin B12 from oral supplementation can prevent deficiency in vegans.3 If a deficiency already exists, most doctors will recommend an initial vitamin B12 injection, then oral amounts ranging from 500 mcg to 1,000 mcg per day until symptoms subside; this is followed by a maintenance level of approximately 10 mcg per day to prevent future deficiencies.
In a person with true PA, initial B12 supplementation should begin with an injection given by a qualified healthcare professional. After blood abnormalities are reversed, maintenance supplementation can be successfully accomplished with oral vitamin B12 at 1,000 to 2,000 mcg (1 to 2 mg) per day and does not require further injections.4 In a person lacking intrinsic factor, only about 1% of this oral amount (10–20 mcg) will be absorbed, but that amount is more than sufficient to prevent future vitamin B12 deficiency.5 , 6 Many physicians are unaware of this well-researched option and thus unnecessarily recommend lifelong B12 injections.7
Vitamin B12 (Depression)
See a doctor for evaluation
Taking vitamin B12 can help counteract deficiencies related to depression.
Deficiency of vitamin B12 can create disturbances in mood that respond to B12 supplementation.8 Significant vitamin B12 deficiency is associated with a doubled risk of severe depression, according to a study of physically disabled older women.9 Depression caused by vitamin B12 deficiency can occur even if there is no B12 deficiency-related anemia.10
Mood has been reported to sometimes improve with high amounts of vitamin B12 (given by injection), even in the absence of a B12 deficiency.11 Supplying the body with high amounts of vitamin B12 can only be done by injection. However, in the case of overcoming a diagnosed B12 deficiency, one can follow an initial injection with oral maintenance supplementation (1 mg per day), even when the cause of the deficiency is a malabsorption problem such as pernicious anemia.
Vitamin B12 (Anemia)
600 to 1,000 mcg daily
Taking vitamin B12 may help prevent and treat anemia. Deficiencies of iron, vitamin B12, and folic acid are the most common nutritional causes of anemia.
Deficiencies of iron, vitamin B12, and folic acid are the most common nutritional causes of anemia.12 Although rare, severe deficiencies of several other vitamins and minerals, including vitamin A,13 , 14 vitamin B2,15 vitamin B6,16 , 17 vitamin C,18 and copper,19 , 20 can also cause anemia by various mechanisms. Rare genetic disorders can cause anemias that may improve with large amounts of supplements such as vitamin B1.21 , 22
Vitamin B12 (Age-Related Cognitive Decline)
Consult a qualified healthcare practitioner
Improved brain function among seniors has been observed after correcting vitamin B12 deficiency with injections, but oral vitamin B12 has not been studied for ARCD. People with ARCD should be tested for vitamin B12 deficiency.
Supplementation with vitamin B12 may improve cognitive function in elderly people who have been diagnosed with a B12 deficiency. Such a deficiency in older people is not uncommon. In a preliminary trial, intramuscular injections of 1,000 mcg of vitamin B12 were given once per day for a week, then weekly for a month, then monthly thereafter for 6 to 12 months. Researchers noted “striking” improvements in cognitive function among 22 elderly people with vitamin B12 deficiency and cognitive decline.23 Cognitive disorders due to vitamin B12 deficiency may also occur in people who do not exhibit the anemia that often accompanies vitamin B12 deficiency. For example, in a study of 141 elderly people with cognitive abnormalities due to B12 deficiency, 28% had no anemia. All participants were given intramuscular injections of vitamin B12, and all showed subsequent improvement in cognitive function.24
Vitamin B12 injections put more B12 into the body than is achievable with absorption from oral supplementation. Therefore, it is unclear whether the improvements in cognitive function described above were due simply to correcting the B12 deficiency or to a therapeutic effect of the higher levels of vitamin B12 obtained through injection. Elderly people with ARCD should be evaluated by a healthcare professional to see if they have a B12 deficiency. If a deficiency is present, the best way to proceed would be initially to receive vitamin B12 injections. If the injections result in cognitive improvement, some doctors would then recommend an experimental trial with high amounts of oral B12, despite a current lack of scientific evidence. If oral vitamin B12 is found to be less effective than B12 shots, the appropriate treatment would be to revert to injectable B12. At present, no research trials support the use of any vitamin B12 supplementation in people who suffer from ARCD but are not specifically deficient in vitamin B12.
Vitamin B12 (Thalassemia)
If deficient: 300 to1,000 mcg daily
Some studies have found people with thalassemia to be frequently deficient in vitamin B12, supplementing with the vitamin may help.
Test tube studies have shown that propionyl-L-carnitine (a form of L-carnitine) protects red blood cells of people with thalassemia against free radical damage.25 In a preliminary study, children with beta thalassemia major who took 100 mg of L-carnitine per 2.2 pounds of body weight per day for three months had a significantly decreased need for blood transfusions.26 Some studies have found people with thalassemia to be frequently deficient in folic acid, vitamin B12,27 and zinc.28 , 29 Researchers have reported improved growth rates in zinc-deficient thalassemic children who were given zinc supplements of 22.5 to 90 mg per day, depending on age.30 , 31 Magnesium has been reported to be low in thalassemia patients in some,32 , 33 but not all,34 studies. A small, preliminary study reported that oral supplements of magnesium, 7.2 mg per 2.2 pounds of body weight per day, improved some red blood cell abnormalities in thalassemia patients.35
Vitamin B12 (Delayed Gastric Emptying, Helicobacter Pylori Infection, Indigestion, Heartburn, and Low Stomach Acidity)
1,000 mcg daily
Vitamin B12 may be beneficial for people with delayed emptying of the stomach in association with Helicobacter pylori infection and low blood levels of vitamin B12.
Vitamin B12 supplementation may be beneficial for a subset of people suffering from indigestion: those with delayed emptying of the stomach contents in association with Helicobacter pylori infection and low blood levels of vitamin B12. In a double-blind study of people who satisfied those criteria, treatment with vitamin B12 significantly reduced symptoms of dyspepsia and improved stomach-emptying times.36
Vitamin B12 (Sickle Cell Anemia)
Consult a qualified healthcare practitioner
People with sickle cell anemia may be deficient in vitamin B12. Intramuscular vitamin B12 injections improved symptoms for patients in one study.
Sickle cell anemia may result in vitamin B12 deficiency. A study of children with sickle cell anemia found them to have a higher incidence of vitamin B12 deficiency than children without the disease.37 A study of 85 adults with sickle cell anemia showed more of them had vitamin B12 deficiency than did a group of healthy people.38 A subsequent preliminary trial demonstrated that for patients with low blood levels of vitamin B12, intramuscular injections of 1 mg of vitamin B12 weekly for 12 weeks led to a significant reduction in symptoms.39 Researchers do not know whether people with sickle cell anemia who are found to be deficient in vitamin B12 would benefit equally from taking vitamin B12 supplements orally.
Preliminary research has found that patients with sickle cell anemia are more likely to have elevated blood levels of homocysteine compared to healthy people.40 , 41 Elevated homocysteine is recognized as a risk factor for cardiovascular disease.42 In particular, high levels of homocysteine in sickle cell anemia patients have been associated with a higher incidence of stroke.43 Deficiencies of vitamin B6, vitamin B12, and folic acid occur more frequently in people with sickle cell anemia than in others44 , 45 , 46 and are a cause of high homocysteine levels.47 A controlled trial found homocysteine levels were reduced 53% in children with sickle cell anemia receiving a 2–4 mg supplement of folic acid per day, depending on age, but vitamin B6 or B12 had no effect on homocysteine levels.48 A double-blind trial of children with sickle cell anemia found that children given 5 mg of folic acid per day had less painful swelling of the hands and feet compared with those receiving placebo, but blood abnormalities and impaired growth rate associated with sickle cell anemia were not improved.49 In the treatment of sickle cell anemia, folic acid is typically supplemented in amounts of 1,000 mcg daily.50 Anyone taking this amount of folic acid should have vitamin B12 status assessed by a healthcare professional.
Vitamin B12 (Phenylketonuria)
Refer to label instructions
Vitamin B12 is found almost exclusively in foods of animal origin, which are restricted on the PKU diet. Supplementing with vitamin B12 may correct a deficiency.
People with PKU may be deficient in several nutrients, due to the restricted diet which is low in protein and animal fat. Deficiencies of long-chain polyunsaturated fatty acids (LC-PUFAs),51 , 52 , 53 selenium,54 , 55 , 56 , 57 vitamin B12,58 and vitamin K may develop on this diet.59
Vitamin B12 is found almost exclusively in foods of animal origin, which are restricted on the PKU diet. People on the PKU diet who are inconsistent in their use of a vitamin B12 supplement may become deficient in this vitamin. In a survey of young adults with PKU, 32% were found to have low or low-normal blood levels of vitamin B12.60 Vitamin B12 deficiency can cause anemia and nerve problems.
Vitamin B12 (Dermatitis Herpetiformis)
Refer to label instructions
Supplementing with vitamin B12 can counteract the nutrient deficiency that often occurs as a result of malabsorption.
People with DH frequently have mild malabsorption (difficulty absorbing certain nutrients) associated with low stomach acid (hypochlorhydria) and inflammation of the stomach lining (atrophic gastritis).61 Mild malabsorption may result in anemia62 and nutritional deficiencies of iron, folic acid,63 , 64 vitamin B12,65 , 66 and zinc.67 , 68 , 69 More severe malabsorption may result in loss of bone mass.70 Additional subtle deficiencies of vitamins and minerals are possible, but have not been investigated. Therefore, some doctors recommend people with DH have their nutritional status checked regularly with laboratory studies. These doctors may also recommend multivitamin-mineral supplements and, to correct the low stomach acid, supplemental betaine HCl (a source of hydrochloric acid).
Vitamin B-Complex (Indigestion, Heartburn, and Low Stomach Acidity)
Refer to label instructions
For people who have inadequate absorption of vitamin B12 due to low stomach acid, supplementing with vitamin B complex can help correct a deficiency.
Vitamin B12 supplementation may be beneficial for a subset of people suffering from indigestion: those with delayed emptying of the stomach contents in association with Helicobacter pylori infection and low blood levels of vitamin B12. In a double-blind study of people who satisfied those criteria, treatment with vitamin B12 significantly reduced symptoms of dyspepsia and improved stomach-emptying times.71
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Last Review: 05-01-2013
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The information presented in Aisle7 is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. Self-treatment is not recommended for life-threatening conditions that require medical treatment under a doctor's care. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires June 2014.
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