Folic acid: benefits, food sources and when to take it

What is folic acid and how does it differ from folate?

Folate is the name for the forms of vitamin B9 found naturally in food. Folic acid is a synthetic form used in supplements and fortified foods [7].

The body uses these forms in different ways. Total intake is expressed in dietary folate equivalents, because natural and added forms are used differently [7].

What is folate for?

The health claims authorised in the European Union state that folate contributes to normal formation of blood cells and takes part in cell division [8]. This does not mean that a supplement on its own treats anaemia or a fertility problem.

At the start of pregnancy, the neural tube forms the brain and spinal cord. NICE explains that folic acid helps prevent neural tube defects and recommends taking it before and during the first weeks of pregnancy [1].

The European declaration for supplements is more specific: supplementary folic acid increases maternal folate, and a low maternal level is a risk factor for neural tube defects [2]. The beneficial effect is obtained with 400 µg daily from at least one month before to three months after conception [2].

Foods that provide folate

Pulses, leafy vegetables, asparagus, broccoli and citrus fruit are food sources of folate [7]. The amount varies with the variety, the portion and the preparation. You can vary the foods you choose without turning every meal into a microgram calculation.

Combine different sources during the week: lentils or chickpeas, leafy greens, broccoli, asparagus and whole fruit. You do not need to match every plate with a figure. The supplement indicated before pregnancy is still needed even if your diet includes folate or there are fortified foods [1].

Liver also contains folate, but during pregnancy it is advised to avoid liver and its derivatives. They contain a lot of vitamin A in the form of retinol, which can harm the baby [3]. You can also consult what to eat and which foods to avoid during pregnancy.

How much folate do you need a day?

For adults, EFSA sets a reference value of 330 µg DFE a day. During pregnancy it sets an adequate intake of 600 µg DFE and, during breastfeeding, a reference value of 500 µg DFE [9]. These amounts describe total intake and do not replace the preventive folic acid regimen.

There is no need to double each portion or to calculate every plate. A varied diet provides folate and other nutrients. If you are pregnant, the team will adjust the regimen to your situation, your test results and the supplements you already take.

When is the 400 microgram supplement recommended?

NICE recommends 400 µg of folic acid a day for anyone who could become pregnant, is planning a pregnancy or is in the first 12 weeks [1]. The ideal is to start three months before trying for a baby. If pregnancy has already started, it should be started as soon as possible and maintained at least during those first 12 weeks [1].

Do not delay starting until you change your diet, reach a specific weight or begin assisted reproduction. A weight or a BMI of 25 or more does not on its own justify exceeding 400 µg daily [1].

When is 5 mg used?

NICE reserves 5 mg daily for situations with higher risk, always within pregnancy planning or the first 12 weeks [1]. The regimen should be offered by the clinical team; do not start it on your own.

• The person, their partner or their family have a history of neural tube defects or other congenital malformations.
• There has been a previous pregnancy affected by a neural tube defect or another congenital malformation.
• There is type 1 or type 2 diabetes.
• There is a haematological condition that requires folic acid, such as sickle cell anaemia or thalassaemia.
• Medicines are taken that affect the absorption or metabolism of folic acid, such as some antiepileptics or HIV treatments.

Being overweight or obese, without any of these factors, does not turn the general regimen into 5 mg [1]. If you have had bariatric surgery, NICE advises seeking individual advice from the bariatric surgery unit about folic acid and other micronutrients [1].

What do I do if I start late or miss a dose?

If the pregnancy has already started and you were not taking the supplement, start the indicated regimen as soon as possible and check whether you have any of the risk factors above [1]. Starting late is not made up for by taking double.

For a single missed dose, the NHS advises taking it when you remember and the next one at its usual time. Do not take two doses to make up for it [5]. If you have questions about a 5 mg prescription, check with whoever prescribed it.

Can you take too much?

EFSA sets a tolerable upper intake level for adults of 1,000 µg of added folate a day. It also applies during pregnancy and breastfeeding, and it counts supplements and fortified foods; it does not include the natural folate in pulses and vegetables [4].

A high-dose prescription responds to a medical indication and is supervised individually. Do not change it on your own to fit this limit.

A high amount can correct anaemia caused by vitamin B12 deficiency while neurological symptoms continue [4]. For that reason, it is worth reviewing all supplements and not adding a prenatal and a multivitamin without checking the total amount.

And in men?

Men also need folate, but a supplement has not been shown to improve fertility on its own. A trial in couples treated for infertility studied 5 mg of folic acid together with 30 mg of zinc [6].

The combination did not increase live births or improve most semen parameters [6]. The result corresponds to that combination and that population; it does not allow the conclusion that folic acid on its own improves or worsens natural conception.

What questions do we see in consultation about folic acid?

Bring a list of medicines and supplements, with their amounts. That way it can be checked whether you already take folic acid, whether there is any interaction, and whether you need the general regimen or a clinical 5 mg regimen.

It is also worth separating three questions: folate from food, the preventive supplement and the study of fertility. None is resolved by increasing the dose without an indication.

The general regimen is 400 µg a day, ideally from three months before trying for a baby. The 5 mg doses are reserved for specific, supervised clinical situations.

When to seek advice if you are trying for a baby and it does not happen?

Folic acid does not treat a cause of infertility. NICE proposes investigating both members of the couple after one year of unprotected vaginal intercourse, if no cause is known [10].

From age 36 it offers specialist referral when you attend consultation. It also brings this forward if there is a known or suspected cause, or a history that increases the risk of infertility [10]. These criteria guide the medical assessment and do not set a different dose of folic acid.

To broaden the context, see food and fertility as a couple and the guide on male fertility and food. Neither replaces your team’s assessment.