A lack of sufficient amounts of vitamin B12 can cause a variety of symptoms that may be seen as unrelated, signs of growing older, due to insomnia or diabetes, or resulting from unusual side effects related to unknown sources. Learn the signs and symptoms of a vitamin B12 deficiency and what can mask those symptoms.
What is Vitamin B12 and Where Do People Get B-12 Naturally?
Vitamin B12 is known by several different names, some of the most common including:
- B-12
- B12
- B Complex vitamin
- bedumil
- cobamin
- cobalamin
Vitamin B12 is a water-soluble vitamin found in foods such as:
- meats, especially liver, beef, and clams
- eggs
- milk and milk products
- fortified foods, such as certain cereals
- some nutritional yeast products
What Levels of B12 are Considered Low?
The Food and Drug Administration does not require that the vitamin B12 content of a food be listed unless the food is fortified with the vitamin. Readers who are interested in determining the amount of vitamin B12 found naturally in foods may wish to review information in the U.S. Department of Agriculture’s Nutrient Database.
Recommended Daily Allowance (RDA) of vitamin B12 varies by age per the National Institutes of Health online article entitled “Dietary Supplement Fact Sheet: Vitamin B12” and includes the following:
- birth to 8 years – 0.4 to 1.2 mcg (moving from lower to higher levels as the child ages)
- 9 to 13 years – 1.8 mcg
- 14 years and older – 2.4 mcg (higher levels for women who are pregnant or lactating)
Blood (serum) levels of vitamin B12 are considered to be less than normal in adults if levels drop below about 170 to 250 pg/mL or 120 to 180 picomol/L, but sometimes a serum vitamin B12 level might not accurately reflect the amount of vitamin B12 that is located in the cells. High serum levels of homocysteine or methylmalonic acid may also indicate a vitamin B12 deficiency.
Common Causes of B12 Deficiency
Levels of vitamin B12 may be low due to a number of reasons, including:
- eating a diet without meat or meat products, such as a strict vegetarian diet or restricted diet due to food allergies or sensitivities
- inadequate absorption of the nutrient due to conditions like pernicious anemia, celiac disease, Crohn’s disease, a lack of intrinsic factor, or low levels of hydrochloric acid in the stomach
- increased levels of normal intestinal bacteria and certain infections
- certain medications, such as chloramphenicol, proton pump inhibitors, H2 receptor antagonists, and metformin
- history of stomach or intestinal surgery
- oral contraceptives
- smoking
- some experience low vitamin B12 levels due to unknown reasons
Symptoms of Vitamin B12 Deficiency
When vitamin B12 levels drop below normal, red blood cells tend to be too large and may not divide properly. The body may have difficulty releasing red blood cells into the blood from the bone marrow, which is where the cells form. Because red blood cells carry oxygen, low levels of circulating red blood cells may result in classic symptoms of fatigue and pale skin.
Additional symptoms of low levels of vitamin B12 include:
- weakness, particularly in the legs
- numbness and/or tingling in the hands and feet
- problems with coordination or balance
- nerve damage
- memory problems, confusion, or dementia
- digestive problems, including constipation, diarrhea, lowered appetite, and weight loss
- soreness of the mouth and/or tongue
- failure to thrive, delays in development, or movement disorders in children
These symptoms may also be caused by a variety of other conditions, so it is important to seek the advice of a healthcare provider in order to determine whether or not these symptoms are related to a deficiency of B12. People with certain conditions, such as pernicious anemia, may be getting adequate amounts of dietary vitamin B12 but may still experience a B12 deficiency.
High levels of folic acid or folate can mask the symptoms of vitamin B12 deficiency. If left untreated, vitamin B12 deficiency may result in permanent nerve damage and can cause memory problems to be more severe. For this reason, healthy adults should generally not take more than 1,000 mcg of folic acid per day.
Vitamin B12 Deficiency May Cause Many Symptoms
Vitamin B12 deficiency may have no obvious symptoms or may cause a wide variety of symptoms that may appear unrelated. These symptoms may be related to other conditions as well. Many people take in adequate amounts of B12 in the diet, but some may need supplementation or foods fortified with vitamin B12. Several body conditions and medications, such as folic acid, can have an effect on the absorption or display of symptoms related to a deficiency in B12.
Untreated vitamin B12 deficiency may result in serious symptoms that could be severe and even permanent. People who may have a vitamin B12 deficiency should see a healthcare provider for further evaluation and specific recommendations regarding treatment, if applicable.
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Information in this article is for informational purposes only and should not be considered medical advice.
Sources:
National Institutes of Health online article entitled “Dietary Supplement Fact Sheet: Vitamin B12”
National Heart Lung and Blood Institute February 2009 online article entitled “What is Pernicious Anemia?”
KwaZulu-Natal Dietitions Department of Health online article entitled “Foods Rich in Folic Acid and Vitamin B12”
RxList online 2010 article entitled “Vitamin B12”
Katrena Wells - Katrena Wells is a RN in NC with 17 1/2 years of experience in oncology, an educator since 1995, and has taught exercise classes since ...
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