Nutrition Science and Everyday Application - beta v 0.1

VITAMINS AND MINERALS INVOLVED IN ENERGY METABOLISM 529
Figure 9.17. Dietary sources of folate. Examples of good sources pictured include spinach,
black-eyed peas, fortified cereal, rice, and bread and asparagus. Source: NIH Office of Dietary
Supplements
Folate Deficiency and Toxicity
Folate deficiency is typically due to an inadequate dietary intake; however, smoking and
heavy, chronic alcohol intake can also decrease absorption, leading to a folate deficiency. 2
The primary sign of a folate deficiency is macrocytic anemia, characterized by large,
abnormal red blood cells, which can lead to symptoms of fatigue, weakness, poor
concentration, headache, irritability, and shortness of breath. Other symptoms of folate
deficiency can include mouth sores, gastrointestinal distress, and changes in the skin, hair
and nails. Women with insufficient folate intakes are at increased risk of giving birth to
infants with neural tube defects and low intake during pregnancy has been associated with
preterm delivery, low birth weight, and fetal growth retardation. 3
Toxicity of folate is not typically seen due to an excess consumption from foods. However,
there is concern regarding a high intake of folic acid from supplements because it could
mask a deficiency in vitamin B 12 . Because folate and vitamin B 12 deficiencies are manifested
by similar anemias, if a person with vitamin B 12 deficiency is taking a high dose of folic
acid, the macrocytic anemia would be corrected while the underlying B 12 deficiency went
undetected, which could result in significant neurological damage. Thus, a tolerable upper
intake level (UL) has been established for folate to prevent irreversible neurological damage
due to high folic acid intake masking a B 12 deficiency. 2