Folic Acid

What is folic acid?

Folic acid, or folate as the naturally occurring form is known, is a vitamin that is necessary for normal cell growth. Folate is found in green, leafy vegetables such as broccoli, green beans and Brussels sprouts and also in oranges. Overcooking vegetables or keeping food hot for long periods can destroy folic acid. Bread and breakfast cereals often have folic acid added to them (food labels will indicate this).

When is it necessary to take extra folic acid?

In 1991, a British study showed that the risk of giving birth to a baby with a neural tube defect was substantially lowered in women who took folic acid supplements during pregnancy. Neural tube defects such as spina bifida occur very early in pregnancy, usually within the first month following conception. Supplements are necessary because the amount of folic acid found naturally in foods is much smaller than the amount required to prevent defects. You would probably need to eat about three times your normal daily amount in order to obtain a sufficient amount of folic acid.

When should folic acid supplements be started?

Ideally, you should begin taking folic acid before conception. If you are planning a pregnancy you should take folic acid supplements from the time that you start trying to conceive until the twelfth week of pregnancy. Some doctors recommend that all women who may become pregnant should take folic acid supplements as a precaution because many pregnancies are unplanned. If you are not taking folic acid and discover you are pregnant, you should start taking a supplement straight away and continue until the twelfth week. It is also recommended that you try to increase your intake of folic acid found naturally by eating more vegetables and fortified cereals.

How much folic acid should be taken?

The Department of Health recommends that a supplement of 400 micrograms of folic acid should be taken daily. It is not harmful if you consume more than this as a result of a good intake of the right foods because the body will automatically get rid of any excess. Women who have previously given birth to a child with a neural tube defect may be advised to take a higher dose of folic acid, eg, 5mg daily.

Folic acid is available on prescription but can also be purchased from pharmacies and most supermarkets. Multivitamins often contain small amounts of folic acid but it is not advisable to take larger quantities of these to ensure a sufficient level of folic acid as it may mean that an excess of other vitamins is also taken. A single supplement of the recommended level of folic acid is the best way to take it.

Should everyone planning a pregnancy take folic acid?

Ideally, all women who are pregnant or trying to conceive should take folic acid supplements. However, in some circumstances caution is required:

  • If you are already taking medicine for a medical condition, particularly epilepsy, you should seek medical advice before taking folic acid.
  • If you or your partner have a family history of neural tube defect, medical advice should be taken as an increased level of folic acid may be recommended.

Further information available from:

The British Nutrition Foundation
Imperial House 6th Floor
15-19 Kingsway
London WC2B 6UN
Tel: 020 7557 7930
Web site:

Fact sheet provided by MIMS

Date last reviewed: October 2016

Register or Subscribe to MIMS

GPs can get MIMS print & online and GPonline for free when they register online – take 2 minutes, and make sure you get your free MIMS access! If you're not a GP, you can subscribe to MIMS for full access.

Register or subscribe

MIMS bulletins

News and updates straight to your inbox.

Prescribing Update: Fortnightly news bulletin
Urgent prescribing updates
Spotlight: Disease-themed monthly round-up

Sign me up

MIMS Dermatology

Read the latest issue online exclusively on MIMS Learning.

Read MIMS Dermatology

Mobile apps

MIMS: access the full drug database and quick-reference tables on the go

MIMS Diagnosis and Management: concise information on signs and symptoms, investigations and diseases

Promo Image

Clinical calculators

Handy calculators and conversions for primary care.