Folate (vitamin B9) is a water-soluble B vitamin needed for DNA synthesis, cell division, and red blood cell production. It works closely with vitamin B12 in several metabolic pathways, and deficiency in either can produce similar symptoms. Folate is found in leafy green vegetables, legumes, fortified cereals, and citrus fruits.
The most widely recognised role of folate is in early pregnancy. Adequate folate at the time of conception and during the first weeks of pregnancy is critical for normal neural tube development. Low folate at this stage may increase the risk of neural tube defects such as spina bifida. Because the neural tube forms very early, often before pregnancy is confirmed, supplementation is recommended from at least one month before conception.
Outside of pregnancy, folate deficiency can cause megaloblastic anaemia, a condition where the bone marrow produces abnormally large, immature red blood cells that do not function properly. Symptoms include fatigue, weakness, shortness of breath, pale skin, and irritability. These overlap with B12 deficiency symptoms, which is one of the reasons testing both vitamins together is often recommended.
Common causes of low folate include poor dietary intake, heavy alcohol consumption (which impairs folate absorption and increases excretion), and malabsorption conditions such as coeliac disease and Crohn's disease. Certain medications, including methotrexate, trimethoprim, and some anticonvulsants, can also interfere with folate metabolism.
This test measures serum folate, reflecting your recent dietary and supplemental intake. A fasting sample is recommended because eating folate-rich foods can temporarily elevate the result. If you are already taking folic acid supplements, the test will reflect that supplementation and results should be interpreted accordingly.
To measure circulating folate and identify whether levels are low, which may contribute to anaemia, impaired cell division, or increased neural tube defect risk in pregnancy.
