Folic acid is the synthetic form of folate, vitamin B9. It is taken before and during early pregnancy to prevent neural tube defects such as spina bifida, and to treat folate deficiency anaemia. Timing matters — the pregnancy benefit depends on taking it before conception.
What is Folic Acid?
Folate is vitamin B9, found naturally in leafy greens, legumes, citrus and liver. Folic acid is the stable synthetic form used in supplements and in food fortification — South Africa has fortified maize meal and bread flour with folic acid since 2003.
Folate is essential for building DNA and for cell division. That makes it most critical wherever cells are dividing rapidly: in a developing embryo, and in the bone marrow producing red blood cells.
Two consequences follow, and they are the whole basis of how it is used:
In early pregnancy, the neural tube — which becomes the brain and spinal cord — forms and closes within the first 28 days, often before a woman knows she is pregnant. Adequate folate at that moment substantially reduces the risk of neural tube defects such as spina bifida and anencephaly.
In the bone marrow, folate deficiency stops red blood cells maturing properly, producing megaloblastic anaemia — large, immature red cells that carry oxygen poorly.
Folic acid is not the same as folate in one important respect. Some people convert folic acid less efficiently; methylfolate is an alternative form sold for that reason. For most people ordinary folic acid works perfectly well, and it is the form the pregnancy evidence is built on.
What is Folic Acid commonly used for?
- Before conception and in early pregnancy, to prevent neural tube defects. This is its most important use.
- Throughout pregnancy and breastfeeding, at a maintenance amount.
- Folate deficiency anaemia, to correct it.
- Alongside methotrexate, which blocks folate — a supplement reduces side effects such as mouth ulcers and nausea.
- In malabsorption, including coeliac disease and inflammatory bowel disease.
- In alcohol dependence, where intake and absorption are often poor.
- In chronic haemolytic anaemias, including sickle cell disease, where red cell turnover is high.
- In kidney dialysis, where folate is lost.
- Alongside other B vitamins to lower homocysteine.
The timing point
Starting folic acid after a positive pregnancy test is often too late for the neural tube benefit. The tube closes by about four weeks — frequently before a missed period is noticed. That is why the advice is to start before conception, ideally at least a month beforehand, and continue through the first trimester.
Because roughly half of pregnancies are unplanned, the general recommendation for anyone who could become pregnant is to take it routinely. Higher amounts are advised for women with a previous affected pregnancy, diabetes, obesity, coeliac disease, or who take certain anticonvulsants — that is a conversation with a doctor, since the higher dose is substantially more than the standard one.
Who commonly looks for Folic Acid and why
- Women planning a pregnancy, or newly pregnant.
- Women told to take it at a first antenatal visit.
- People diagnosed with folate deficiency anaemia.
- People on methotrexate for rheumatoid arthritis or psoriasis.
- People with sickle cell disease or another chronic anaemia.
- People on certain anticonvulsants, which deplete folate.
- People with coeliac disease or another malabsorption condition.
- Anyone told their blood count showed large red cells.
What to check on the label before taking Folic Acid
Check the amount, because the pregnancy doses differ substantially. There is a standard preventive amount and a considerably higher one for women at increased risk. Taking the standard amount when you need the higher one means missing much of the benefit — so if any of the risk factors above apply, confirm which you should be on.
Check whether your prenatal multivitamin already contains it, so you are not doubling up unintentionally.
Note that fortified staples contribute too — maize meal and bread flour in South Africa are fortified — though not enough to replace a supplement when one is indicated.
Speak to a pharmacist or doctor if:
- You are planning a pregnancy, so you start early enough and on the right amount.
- You have a previous pregnancy affected by a neural tube defect, diabetes, a high BMI, or take an anticonvulsant — you likely need the higher amount.
- You take methotrexate — the timing relative to your methotrexate dose matters, so follow the instruction given.
- You have anaemia that has not been investigated.
- You take anticonvulsants, sulfasalazine or trimethoprim-containing antibiotics such as co-trimoxazole, which interact with folate.
- You have had gastric surgery or have a malabsorption condition.
Safety, interactions and when to seek professional advice
The important caution is B12. Folic acid corrects the blood picture of B12 deficiency — the anaemia improves and the large red cells normalise — while doing nothing about the nerve damage B12 deficiency causes. That damage can then progress silently and may become irreversible.
So anaemia should be investigated before treating it with folate alone. A doctor will normally check B12 as well. This matters most in older adults, vegetarians and vegans, people on long-term metformin or acid-suppressing medicines, and anyone with pernicious anaemia. If you have nerve symptoms — tingling, numbness, unsteadiness — alongside anaemia, say so.
Folic acid is otherwise well tolerated. Side effects are uncommon; nausea, bloating and appetite changes occur occasionally.
Do not take large amounts long term without a reason. There is no benefit beyond correcting deficiency and meeting the pregnancy requirement.
Anaemia is a finding, not a diagnosis. Iron deficiency, B12 deficiency, thalassaemia, chronic disease and blood loss all cause it, and the treatments differ. Persistent tiredness, breathlessness or pallor should be investigated rather than self-treated.
Seek medical attention for anaemia symptoms that have not been assessed — tiredness, breathlessness, pallor, palpitations; for tingling, numbness or unsteadiness alongside anaemia; for a rash or breathing difficulty after taking it; or if you are pregnant and unsure which amount you should be taking.
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Frequently asked questions
What is folic acid used for? Preventing neural tube defects such as spina bifida when taken before and during early pregnancy, and treating folate deficiency anaemia.
When should I start taking it for pregnancy? Before conception — ideally at least a month beforehand — and continuing through the first trimester. The neural tube closes by about four weeks, often before a pregnancy is known.
Is it too late if I have just found out I am pregnant? Start immediately and speak to a doctor or midwife. Much of the neural tube benefit depends on earlier intake, but folate remains important through pregnancy.
Do I need a higher dose? Possibly. Women with a previous affected pregnancy, diabetes, a high BMI, coeliac disease or on certain anticonvulsants are usually advised a considerably higher amount. Confirm with a doctor.
Why does my doctor check B12 as well? Folic acid can correct the anaemia of B12 deficiency while nerve damage continues unnoticed. Checking both avoids masking it.
Is folate the same as folic acid? Folate is the natural form in food; folic acid is the synthetic form in supplements and fortified flour. Methylfolate is an alternative form some people prefer.