# Folic acid

Source: https://synapse-lifestyle.com/en/reference-guide/biomarkers/folate

Unit: ng/mL

## What is Folic acid?

Folic acid is vitamin B9. Your body uses it to build new cells, from red blood cells to the lining of your gut. In food this vitamin is called folate; folic acid is the manufactured form used in supplements. A low value can leave you tired, and it is always read alongside your vitamin B12.

## Clinical frame

Folate is a cofactor in one-carbon metabolism and therefore in the synthesis of **purines and thymidylate**. In deficiency, DNA synthesis falters first in rapidly dividing tissue, presenting as **megaloblastic anaemia** with a raised MCV [3]. Serum folate mainly reflects recent intake; red-cell folate gives a steadier picture of the store.

Periconceptional supplementation lowers the risk of **neural tube defects**. The MRC trial found a reduction of about 70 % in women with a previously affected pregnancy [1]; the systematic review confirms the effect for a first pregnancy as well [2]. The neural tube closes around day 28, so starting after a positive test is too late. The advice is **400 micrograms a day**, from planning until week twelve.

Folic acid and vitamin B12 give the same haematological picture. Folate supplementation can correct the anaemia of a **B12 deficiency** while the neurological damage advances, so a **B12 measurement** belongs with every low folate result [3]. Alcohol, malabsorption such as coeliac disease, and folate antagonists such as methotrexate are the usual causes of an acquired shortage.

## What moves this value?

Few green vegetables or pulses, long boiling in plenty of water, regular alcohol, a bowel condition and certain medicines all pull your value down.

Vegetables every day and pulses regularly, briefly steamed rather than long boiled, usually lift your value quickly. When you are planning a pregnancy a supplement of 400 micrograms a day is the rule; discuss a low value with your doctor.

Developed and reviewed with the Synapse [medical advisory board](https://synapse-lifestyle.com/en/advisory-board).

## References

1. MRC Vitamin Study Research Group. Prevention of neural tube defects: results of the Medical Research Council Vitamin Study. Lancet 338, 131–137 (1991). (PMID 1677062) https://doi.org/10.1016/0140-6736(91)90133-A
2. De-Regil, L. M. et al. Effects and safety of periconceptional oral folate supplementation for preventing birth defects. Cochrane Database Syst Rev 12, CD007950 (2015). (PMID 26662928) https://doi.org/10.1002/14651858.CD007950.pub3
3. Stabler, S. P. Vitamin B12 deficiency. N Engl J Med 368, 149–160 (2013). (PMID 23301732) https://doi.org/10.1056/NEJMcp1113996

- [All biomarkers in the guide](https://synapse-lifestyle.com/en/reference-guide#biomarkers)

The colour zones are personal: they depend on age, sex, risk and history, and appear in the patient's own report.

Insights to discuss with the patient, not a diagnostic instrument.