Yan Lin
KNH 413
M.S Matuszak
Medical Nutrition Therapy Nutrient – Folic Acid
1. What is the nutrient?
Folic acid is a water soluble B vitamin. It is used in various ways in our body. Folic acid,
vitamin B6, and vitamin B12 work together to lower serum homosysteine level. High
serum homosysteine level increases risk for cardiovascular disease. Folic acid also helps
form red blood cells and genetic materials within each body cell. It also plays a part in
protein metabolism.
2. What is the RDA/DRI for the nutrient?
Age (years)
Male and Females
(μg)
1-3
150
4-8
200
9-13
300
14-18
400
19+
400
Pregnancy
(μg)
N/A
N/A
N/A
600
600
Lactation
(μg)
N/A
N/A
N/A
500
500
3. How is the nutrient metabolized?
Folic acid is absorbed primarily from the small intestine. It is then metabolized in the
liver into 7,8-dihydroFolic Acid and eventually converted to 5,6,7,8-tetrahydroFolic Acid.
Folic acid is metabolized by donating one carbon unit in various biosynthetic pathways.
Folate coenzymes act as acceptors and donors of one-carbon units in a variety of
reactions which are important to the metabolism of nucleic acids and amino acids.
4. What are food sources of the nutrient?
Good sources for folic acids include:
1. green leafy vegetables and asparagus
2. whole wheat products and fortified breakfast cereals
3. citric fruits or juices, strawberries, cantaloupe and other melons
4. animal livers, kidneys, sunflower seeds, eggs, peas, and dried beans.
5. What disease states alter the nutrients metabolism?
During pregnancy and lactation, the requirement for folic acid is elevated. People who
abuse alcohol also need higher levels of folic acid. Other medical conditions that result
in higher levels of folic acids include malabsorption, liver disease, kidney dialysis, and
certain anemias.
6. What are the tests or procedures to assess the nutrient level in the body?
RBC folic acid measurement is a test used to measure the amount of folic acid in red
blood cell. It is done primarily for assessing the risk of folic acid deficiency or neural tube
defect. Other tests ordered to assess vitamin B12, homocysteine, and methymelonic
acid levels are also used to check for the possibility of folic acid deficiency.
7. What is the drug - nutrient interactions?
Medications that interfere with folic acid utilization include anticonvulsant medications,
metformin (controlling blood sugar in type-2 diabetes), sulfasalazin, triamteren,
methotrexate, and barbeturates. When taking these medications, the total intake of
folic acid needs to be increased.
8. How is the nutrient measured?
RBC folic acid measurement can be ordered along with vitamin B12, homocysteine, and
methymelonic acid tests to assess the folic acid status in the body. The normal range for
children 2-6 is >160ng/mL, for adolescent older than 16 is 140-628ng/mL, and for adults
is 150-450ng/mL.
9. What is the Upper Tolerable Limits?
Age
Male and Females
(years)
(μg)
1-3
300
4-8
400
9-13
600
14-18
800
19+
1000
Pregnancy
(μg)
N/A
N/A
N/A
800
1000
Lactation
(μg)
N/A
N/a
N/A
800
1000
10. What are the physical signs of deficiency?
The physical signs of deficiency include neural tubal defect in infants, slow growing rate
in infants and children, and folate deficiency anemia in adults. Others include diarrhea,
loss of appetite, fatigue, weakness, high level of blood homocysteine, and etc.
11. What are physical signs of toxicity?
Too much folic acid from dietary source would not cause any health concern, however,
low toxicity would result from too much folic acid supplementation or folic acid fortified
foods intake. Excess folic acid intake will be excreted in urine. However, research
indicated that excess folic acid consumption was associated with vitamin B12 deficiency
anemia which resulted in large red blood cells.
References:
1. Office of Dietary Supplement. Folate. Retrieved from
http://ods.od.nih.gov/factsheets/folate/
2. The Ohio State University. Folate. Retrieved from http://ohioline.osu.edu/hygfact/5000/5553.html
3. Oregon State University. (2007). Folic acid. Retrieved from
http://lpi.oregonstate.edu/infocenter/vitamins/fa/
4. Marinus, M.G. Folic acid metabolism. Retrieved from
http://users.umassmed.edu/martin.marinus/Mph200/FolicAcidMetabolism.pdf
5. University of Maryland Medical Center. (2011). Folic acid. Retrieved from
http://www.umm.edu/altmed/articles/vitamin-b9-000338.htm
6. Medical Center of South Carolina. Folic acid measurement, RBC. Retrieved from
http://www.muschealth.com/lab/content.aspx?id=150003
7. Lab Tests Online. Vitamin B12 and folic acid. Retrieved from
http://labtestsonline.org/understanding/analytes/vitamin-b12/tab/test
8. Klee, G., G., Cobalamin and folate evaluation: measurement of methylmalonic acid and
homocysteine vs vitamin B12 and folate, retrieved from Clinical Chemistry at
http://www.clinchem.org/content/46/8/1277.full