The B vitamins are a class of water soluble vitamins which have various functions regarding cell metabolism within the body. All eight of the vitamins have individual names, however, when provided together they are referred to as Vitamin B Complex. Two of these vitamins, B12 and folic acid, are routinely measured when people complain of chronic fatigue. Lack of B12 and folic acid in the diet will lead to deficiencies in the body, causing people to report feeling tired.
Functions in the Body
B12 is responsible for nutrient metabolism and formation of the insulation sheath around nerve cells. Folic acid is essential in cell growth, specifically in pregnancy, and in the transfer of inherited traits between cells. Both B12 and folic acid aid in replacement and maintenance of the genetic code for all cells within the body.
Deficiency
Poor dietary intake of B12 or folic acid will lead to deficiencies in the body. Lack of intrinsic factor secreted from the stomach will lower B12 absorption, also leading to deficiency. A deficiency in either B12 or folic acid leads to megaloblastic anemia. This form of anemia is characterized by red blood cells that are large, fragile and few in number. Individuals experience fatigue because of the impaired oxygen carrying ability in these red blood cells. It is important to test B12 and folic acid levels if a megaloblastic anemia is suspected because a folic acid deficiency can mask a deficiency in B12 which will lead to irreversible nerve damage if untreated.
Other Symptoms
Anemia is not the only symptom of these deficiencies. B12 deficiency is also characterized by diarrhea, lack of appetite, lack of energy, nerve damage and a red swollen tongue. Other symptoms of folic acid deficiency include diarrhea, mouth ulcers, poor growth and a swollen tongue. During pregnancy, folic acid deficiency can result in neural tube defects.
Daily Recommended Intake
According to the Daily Recommended Intake or DRIs, adult men and non-pregnant women should consume 2.4 µg/d of B12 and 400 µg/d of folic acid to stay healthy. The best way to meet the recommended levels is to eat a variety of foods containing these nutrients. B12 is only found in foods of animal origin and fermented soybeans. Foods containing B12 include meat, fish, eggs, dairy, and miso. Folic acid can be found in foods such as Brewer's yeast, liver, dark green leafy vegetables, oranges, and bananas. Both vitamins can also be found in fortified foods, such as ready-to-eat dry cereal.
Individuals at Risk
Two groups of individuals who are primarily at risk of developing megaloblastic anemia are the elderly and vegetarians or vegans. The elderly are at risk because the body produces less intrinsic factor with age, decreasing the amount of B12 absorbed from food. Secondly, strict vegetarians or vegans who consume no animal products are at risk. Those who are at risk for B12 and folic acid deficiencies should monitor their dietary intake and make appropriate changes in order to get enough of the vitamins. A physician or dietitian may also recommend a daily multivitamin or B-Complex supplement.
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