Folate (Vitamin B9)

Serum Folate

Clinical Information

Also known as folate, folic acid. Around 30-50% of which are found in the mitochondria.

This is essential for metabolic activities for cell growth and replication. It is serves as a cofactor in the synthesis of thymidylate, purines and methionine, and other methylation reactions1.

Signs and Symptoms of Deficiency or Toxicity

Severe deficiency leads to megaloblastic anemia. Signs and symptoms of which are fatigue, weakness, and shortness of breath2.

Folate deficiency normally occurs with other nutritional deficiencies. The most common cause of inadequate dietary intake. Other causes are secondary causes such as liver disease, hemolytic disorders, malignancies, and rare inborn errors of metabolism3. People who are at risk to folate deficiency are people with alcohol dependence, women of reproductive age, pregnant women, and those with malabsorptive disorders3.

Toxicity of water-soluble vitamins is unlikely2 and is excreted in the urine4, 5.

Biomarker and Methods of Analysis


Serum folate is more reproducible and faster to perform than red cell folate; it is influenced by fewer analytical variables and provides an assessment of folate status that may be superior to red cell folate6.

Supplementation Guide

Routine folic acid supplementation is recommended from at least a month before conception and throughout the first 1 weeks of pregnancy to reduce neural tube defect in baby. Dosing recommendation is 500 micrograms per day. Meanwhile, women with chronic hemolytic conditions including beta thalassemia should be provided with a higher dose of folic acid of 5 mg per day7

Following are UL per age group8.

  • In children:
    • 1-3 y.o.:30 mcg DFE
    • 4-8 y.o. 400 mcg DFE
    • 9-13 y.o.: 600 mcg DFE
    • 14-18 y.o.: 800 mcg DFE
  • In adults, 19 years and older, 1000 mcg DFE
  • Among pregnant/lactating women:
    • 14-18 y.o.: 800 mcg DFE
    • 19 and older, 1000 mcg DFE

High intakes of folic acid may mask vitamin B12 deficiency3.

Folic acid may possibly interact with anticonvulsants, barbiturates, methotrexate, and pyrimethamine9.

Food Sources

Folate is widely found in food especially in dark green leafy vegetables. Fruits and fruit juices, nuts, beans, dairy products, poultry and meat, eggs, seafood, and grains. The richest source of folate are spinach, liver, yeast, and brussel sprouts3.

(1) Huskisson E, Maggini S, Ruf M. The role of vitamins and mineral in energy metabolism and well-being. The Journal of International Medical Research 2007; 35: 277-289
(2) Higdon J, Drake VJ, Delage B. (July 2015). Micronutrient Information Center. Biotin.Retrieved from
(3) Office of Dietary Supplements-National Institutes of Health. Folate. Dietary supplement Fact Sheet. Retrived from
(4) Mayo Clinic Medical Laboratories. (n.d.) Test Catalog. Vtamin B12 and Folate, Serum. Retrieved from
(5) Sriram K and Lonchyna VA. Micronutrient supplementation in adult nutrition therapy: Practical considerations. Journal of Parenteral and Enteral Nutrition 2009; 33(5): 548-562.
(6) Bralley, J.A., Lord, R.S. (2012). Laboratory Evaluations for Integrative and Functional Medicine. 2nd ed. Duluth, Ga: Metametrix Institute.
(7) The Royal Women’s Hospital. (May 15, 2017). Guideline. Folate in Pregnancy. Retrived from
(8) Philippine Dietary Reference Intakes. 2015. Department of Science Technology-Food and Nutrition Research Institute.
(9) Mayo Clinic Staff. (October 24, 2017). Folate (folic acid). Retrieved from