Folic acid tablets: how much to take, folate vs folic acid, and whether you need methylfolate

What folic acid is for

Folate (vitamin B9) is needed for cell division and to make red blood cells. The NHS says adults need 200 mcg of folate a day, and most people get it from food: leafy greens, peas, pulses and fortified breakfast cereals.

You’d usually take a separate folic acid tablet if:

• you could get pregnant or are planning to – the main reason by far;
• a blood test shows folate deficiency, in which case your GP sets the dose and how long;
• you take certain medicines, such as low-dose methotrexate for rheumatoid arthritis, and your doctor has added folic acid.

If your folate is already fine, an extra tablet won’t give you more energy or better health. If you’re unsure what you need, start with our vitamin check.

Folate vs folic acid vs methylfolate

Because absorption differs, US labels give folate in mcg DFE (dietary folate equivalents). 400 mcg of folic acid taken with food is about 667 mcg DFE. Look for the folic acid figure in brackets: “667 mcg DFE (400 mcg folic acid)”.

Folic acid before pregnancy: the NHS dose

Folic acid lowers the risk of neural tube defects – serious conditions affecting the baby’s brain and spine, such as spina bifida. The neural tube forms in the first weeks of pregnancy, so you need to start before you conceive.

NHS and NICE advice:

• 400 mcg a day if you could get pregnant, are planning a pregnancy or are in the first 12 weeks;
• start ideally 3 months before you begin trying, and continue until the end of week 12;
• if your pregnancy wasn’t planned, start as soon as you find out;
• a BMI of 25 or more doesn’t need a higher dose on its own, according to NICE’s 2025 guidance.

5 mg a day is prescription-only. NICE gives these examples of higher risk:

• a neural tube defect or other birth defect in you, your partner, your family or a previous pregnancy;
• type 1 or type 2 diabetes;
• sickle cell disease or thalassaemia;
• anti-epilepsy medicines or medicines for HIV.

If you’ve had weight-loss surgery, NICE advises asking your bariatric unit for individual advice.

Not sure which dose applies to you? Pick your situation:

See the full timeline, with vitamin D and iodine, in our guide to pregnancy vitamins.

How to take folic acid tablets

Usually one 400 mcg tablet a day, at the same time each day – next to the kettle is a good place to keep the pot. With or without food doesn’t matter much: on an empty stomach nearly all of it is absorbed, and with food at least 85%.

Most people who get it wrong are doubling up. Folic acid is in pregnancy formulas, multivitamins, B complexes and “women’s” inositol. Add up what you get from every bottle:

If you’re eligible for Healthy Start (England, Wales and Northern Ireland), the free vitamins for pregnancy already contain 400 mcg of folic acid, so you don’t need a second tablet.

MTHFR and methylfolate: the hype

MTHFR is an enzyme that helps turn folate into its active form. A common gene variant (C677T) is often called a “mutation”. About 25% of Hispanic people and 10% of white and Asian people carry two copies, according to NIH ODS. One copy is even more common.

That’s the basis of the marketing for “methylated” vitamins: the claim that folic acid doesn’t work if you have MTHFR. The CDC says plainly that this isn’t true:

• people with an MTHFR variant can process all types of folate, including folic acid;
• folic acid is the only type of folate shown to help prevent neural tube defects;
• if you have the variant and could get pregnant, the CDC advises the same 400 mcg of folic acid a day.

NIH ODS says some people with the variant might do better on methylfolate, but the evidence is inconclusive. Methylfolate is a reasonable option, not a requirement. And because the folic acid advice is the same with or without the variant, a genetic MTHFR test won’t change which vitamins you need.

The 1 mg limit and masking low B12

For adults, the upper limit is 1,000 mcg (1 mg) a day of folic acid from supplements and fortified foods. EFSA says the limit covers methylfolate too. It doesn’t apply to folate from ordinary food.

Why bother counting:

• the NHS warns that more than 1 mg of folic acid a day can hide the symptoms of B12 deficiency. The anaemia improves while nerve damage continues. Older people are at greater risk because B12 absorption falls with age. More in our vitamin B12 guide;
• the evidence on risks is mixed. In one Norwegian trial, 800 mcg of folic acid a day plus B12 was linked to more cancer. There’s no evidence that moderate doses harm you, but no benefit from extra either;
• NIH ODS cites data linking 1,000 mcg a day or more around conception with slightly lower cognitive test scores in children at age 4–5.

This is why the NHS checks B12 before treating folate deficiency. If you’re vegan or over 50, taking folate together with B12 is the practical choice.

Who should take care: medicines and conditions

• Methotrexate. Folate works against it. If you’re having cancer treatment, don’t take folate without your oncologist’s agreement. For rheumatoid arthritis and psoriasis, folic acid is sometimes prescribed with methotrexate to reduce side effects; your doctor sets the dose and days.
• Anti-epilepsy medicines (phenytoin, carbamazepine, valproate). They lower blood folate, and folate may lower their levels. Take it only on advice; in pregnancy, this is a reason for the 5 mg dose.
• Sulfasalazine reduces folate absorption.
• Numbness, pins and needles or anaemia – get your B12 checked first.
• Pregnancy after weight-loss surgery – ask your bariatric unit.

Folate in food and fortified flour

Folate is found in leafy greens, peas, pulses, broccoli and liver. Avoid liver in pregnancy because of its vitamin A.

Across the UK, millers must add folic acid to non-wholemeal wheat flour by the end of 2026. Food Standards Scotland says this could cut neural tube defects by 20%. It doesn’t replace the 400 mcg tablet if you’re trying to conceive: a sandwich isn’t a measured dose.

Outside pregnancy, food is usually enough. What else women may need at different ages is covered in our guide to supplements for women.

How to choose folic acid on iHerb

1. Decide why you need it: planning a pregnancy, a deficiency on a blood test, or your GP’s advice.
2. For pregnancy, choose 400 mcg of folic acid per tablet. Only a doctor can prescribe 5 mg.
3. Choose methylfolate only if you’ve agreed it with your GP. It costs more, and it hasn’t been shown to be better for MTHFR.
4. Add up folic acid and methylfolate across all bottles: no more than 1,000 mcg a day unless prescribed.
5. Before pregnancy, check there’s no retinol in the formula (retinyl palmitate, retinyl acetate).
6. If you’re over 50 or vegan, consider B12 alongside folate. Combined formulas are covered in our guide to the vitamin B complex.