Folic acid before pregnancy: how much and when to start

Why does folic acid matter before you are pregnant?

The neural tube becomes the brain and spinal cord, and it closes by about week 6 of pregnancy. Counting from the first day of your last period, that is only a couple of weeks after a missed period. Many people have not taken a test by then, which is why the advice begins before you conceive.

Folic acid takes time to build up, so a few weeks of steady use before conception gives the best protection. If you are already pregnant and have not started, begin as soon as you can.

How much folic acid should you take?

Almost every national authority recommends 400 mcg a day for people at standard risk. The purpose is shared, and the timing and wording differ from country to country.

The shared message is to start before you conceive and keep going through the early weeks. Where the end date differs, follow your own country's advice, or your national health ministry if yours is not listed.

A 10-week or 12-week end date covers folic acid specifically. It does not mean you should stop every prenatal vitamin then. Your needs for iron, iodine, vitamin D and other nutrients continue, and the prenatal vitamin guide explains how to choose a product you can keep taking.

If your cycle is irregular or you are coming off birth control, start a daily vitamin as soon as you decide to try. The birth control guide explains how quickly fertility can return.

Do you need a higher dose?

Some people need more than 400 mcg, and a provider sets that dose. A higher dose may be advised if you:

• have diabetes,
• take medicine for epilepsy,
• have had a pregnancy affected by a neural tube defect, or have a close relative who has,
• have a condition that affects how you absorb nutrients, such as some bowel diseases or weight-loss surgery.

In the UK, this is usually a prescribed 5 mg tablet, and other countries, including Ireland and France, send these situations to a clinician and use their own protocols. Do not take more than 1 mg of folic acid a day without advice, and do not combine several multivitamins to reach a bigger number. A pharmacist can add up the totals.

Folate from food: what counts?

Folate is the natural form found in leafy greens, lentils, chickpeas, beans, asparagus, avocado and oranges. Many countries add folic acid to flour, pasta or cereal, so check the labels on staples you buy.

Food folate is good for you. Because the amount you absorb varies, advice is to take a folic acid supplement in addition to a varied diet. The recommended total folate intake in pregnancy, about 600 mcg of dietary folate equivalents in both the US and the European Food Safety Authority reference values, is a target for food and supplements combined. It is a different number from the 400 mcg supplement dose, so they are not meant to be added together.

How do you read the label?

• Look for "folic acid" in micrograms. A dose of 400 mcg or 0.4 mg is the standard amount. One milligram equals 1,000 micrograms.
• Do not add DFE and folic acid together. One mcg of dietary folate equivalents (DFE) equals 1 mcg of food folate or 0.6 mcg of folic acid taken with food, so one ingredient can show two numbers.
• Check your prenatal vitamin first. Most already contain folic acid, so a second folic acid pill usually creates a duplicate.
• Mind the full serving. Some brands split a day's dose across capsules.
• Know the upper limit. In the US, the safe upper limit for folic acid from supplements and fortified foods is 1,000 mcg a day for adults, unless a clinician directs a higher treatment dose.

What about MTHFR and methylfolate?

Some products promote "methylfolate" for people with common MTHFR gene variants. The CDC explains that people with common variants can process folic acid, and that 400 mcg raises blood folate whatever the genotype. Folic acid is the form shown in research to prevent neural tube defects.

A common MTHFR variant is not, by itself, a reason to avoid folic acid, and a higher price does not make a product more effective. If a doctor has told you about a specific concern, follow that advice. Otherwise a standard 400 mcg product remains a sound choice.

Does the partner need folic acid?

For conception, the research does not point to a need. In a large trial of couples seeking fertility treatment, men who took folic acid and zinc did not see better semen quality or more live births than men who took a placebo. A healthy diet and an assessment for any concerns do more than a tablet, and our male fertility guide covers what helps.