Folic acid: doses, foods and side effects

Are there foods to avoid when taking folic acid?

No. There's no food you need to cut out while you take folic acid, and it's fine to keep eating folate-rich foods and fortified cereals. The one thing the NHS flags is alcohol: it says to avoid or limit it, because alcohol can affect how well folic acid works.

Tea may make a small difference. In a German study, healthy volunteers swallowed folic acid with water, green tea or black tea on separate occasions. At the 0.4 mg dose, green and black tea both lowered the peak level of folate in the blood by about 39%, and lowered the total amount absorbed by about 27% and 18% respectively. It was a single-dose study using tea extract, and it didn't measure whether folate levels fell over weeks, so it doesn't mean you need to give up tea. Taking your tablet with water, as the NHS suggests, and having your cup of tea later costs you nothing.

Fortified food isn't something to avoid either. When the UK decided to add folic acid to flour from December 2026, it kept the level at 250 µg per 100 g partly so that people wouldn't go over the 1 mg a day guidance level, and EFSA's 2023 safety review found the evidence insufficient to link folate intake to impaired thinking or to bowel or prostate cancer.

Can you drink milk while taking folic acid?

Yes. The NHS folic acid page doesn't list milk, or any food, as a problem; its only food and drink advice is about alcohol. The worry may come from iron tablets, where the NHS says tea, eggs and milk can affect how well the medicine works.

What should you not mix with folic acid?

Some medicines. The NHS says these may not mix well with folic acid:

• epilepsy medicines such as phenytoin, phenobarbital and primidone
• the antibiotics chloramphenicol and co-trimoxazole
• sulfasalazine, used for ulcerative colitis, Crohn's disease and rheumatoid arthritis
• lithium
• aspirin, for pain relief or to thin the blood

If you take any of these, talk to your GP or pharmacist before starting folic acid. Methotrexate is a special case: doctors sometimes prescribe folic acid alongside it to prevent side effects, so follow their instructions rather than adding your own supplement.

What are the benefits of folic acid?

The best-established benefit is preventing neural tube defects such as spina bifida when it's taken before and in early pregnancy. A 2015 Cochrane review of five trials, involving 7,391 women, found that folic acid, alone or with other vitamins and minerals, cut the risk of these birth defects by about 70% compared with no folic acid (risk ratio 0.31). Folic acid tablets are also a treatment for folate deficiency anaemia, prescribed by a GP.

Beyond pregnancy, folate (the family of vitamin B9 compounds that includes folic acid) has a set of authorised roles in GB law. Folate contributes to normal blood formation, normal amino acid synthesis, normal homocysteine metabolism, normal psychological function, the normal function of the immune system and the reduction of tiredness and fatigue, and it has a role in cell division. These describe what the vitamin does in your body, and they aren't evidence that taking extra helps if you already get enough.

Can men take folic acid?

Yes. The NHS says adults need 200 micrograms of folate a day, and that men, and women who can't get pregnant, should be able to get all the folate they need from a varied and balanced diet; the 400 microgram advice is for people who could become pregnant.

What does folic acid do for men?

The same as for anyone: folate contributes to normal blood formation and the reduction of tiredness and fatigue, among its authorised roles. It's often sold for male fertility, but a large trial didn't support that. In the US Folic Acid and Zinc Supplementation Trial, published in 2020, 2,370 men whose couples were planning fertility treatment took 5 mg of folic acid and 30 mg of zinc, or a placebo, every day for six months. Sperm counts, movement and shape were no better, live birth rates were the same (34% and 35%), and the supplement group had more stomach upset and slightly more sperm DNA damage. If you have a neural tube defect, or a relative with one, tell your partner's GP, because she may need the higher 5 mg dose.

What are the side effects of folic acid?

Not everyone gets them. The NHS lists bloating, wind, feeling sick and loss of appetite for tablets, and adds diarrhoea, vomiting and a skin rash, which may be itchy, for liquid folic acid. Rarely, folic acid can cause anaphylaxis, a serious allergic reaction with a swollen face, throat or tongue and difficulty breathing, which needs emergency help.

The more serious risk is easy to miss. Doses above 1 mg a day can mask the symptoms of B12 deficiency, which can eventually damage the nervous system, so the NHS checks B12 before treating anyone with folic acid. The NHS also says folic acid may not be suitable if you have B12 deficiency anaemia or pernicious anaemia, a coronary stent, or cancer. Our guide to B12 deficiency explains why this matters.

What are the symptoms of folic acid (folate) deficiency?

Mostly tiredness and the symptoms of anaemia. Doctors call it folate deficiency, because the NHS describes folic acid as the man-made form of folate. The NHS lists feeling weak or tired, shortness of breath, headaches, palpitations, a sore or red tongue (sometimes with mouth ulcers), indigestion, loss of appetite, diarrhoea, problems with your vision and problems with memory, understanding and judgement. The BDA adds weight loss. These are almost the same as the symptoms of B12 deficiency, so a blood test should decide what you take.

Common causes include a diet low in folate, regularly drinking too much alcohol, conditions such as coeliac disease that affect absorption, pregnancy, and some medicines, which the NHS says include some anticonvulsants, colestyramine, sulfasalazine and methotrexate. If you have symptoms, see a GP. Treatment is usually folic acid tablets for about 4 months, after your B12 has been checked. If you take high-dose biotin, tell the person taking your blood: an NHS hospital laboratory warns that biotin at 5 mg a day or more can make a folate result look falsely high.

How much folic acid should you take before and during pregnancy?

400 micrograms (400 mcg, or 0.4 mg) a day for most people, and 5 mg for those at higher risk. Most women's folate levels aren't high enough without a supplement: in the UK's National Diet and Nutrition Survey for 2016 to 2019, 89% of women aged 16 to 49 had red blood cell folate below the level linked to a higher risk of neural tube defects.

The BDA's list for the higher dose also includes living with obesity, so ask your GP if you're unsure which applies to you.

Folic acid before pregnancy: when should you start?

Before you start trying, ideally 3 months before. Folate levels take time to build: in a 2006 trial of 144 women, folate in the blood levelled off after 12 weeks of daily supplements, but red blood cell folate was still rising at 24 weeks. If you find out you're pregnant and haven't been taking it, start as soon as you know. The NHS says taking it beyond 12 weeks won't harm your baby. Fortifying flour from December 2026 won't change this: the UK's chief medical officers say the supplement advice continues.

A pregnancy multivitamin providing 400 micrograms also works, the BDA says. The NHS asks you to check with a doctor or pharmacist before taking a multivitamin with folic acid in pregnancy, and not to take supplements containing vitamin A, or cod liver oil, while pregnant.

What's the best time to take folic acid?

Whenever you'll remember it every day. The NHS doesn't set a time of day. It says to swallow tablets whole with a glass of water, or to measure liquid folic acid with the syringe or spoon provided. Water rather than tea is sensible given the tea study above. If you forget a dose, the NHS says to take it as soon as you remember and then carry on at the usual time, and never to take two doses to make up.

Can you take folic acid as gummies?

The NHS doesn't mention gummies: it describes folic acid as tablets or a liquid, plus multivitamin tablets and capsules. If you're considering a gummy, check these points:

• The label says folic acid, not folate or methylfolate, if you're following the NHS pregnancy advice. Our guide to folate vs folic acid explains the difference.
• The amount is 400 micrograms per serving, and you know how many gummies make a serving.
• A multivitamin gummy contains no vitamin A (retinol) if you could be pregnant, and you've checked with a pharmacist or doctor, as the NHS asks.
• It's for an adult: the NHS says multivitamins containing folic acid are not recommended for children under 12.
• The sugar per serving is low enough: the NHS says adults should have no more than 30 g of free sugars a day.

If a GP prescribed 5 mg, don't swap it for a gummy.

Can you take folic acid and vitamin D together?

The NHS advises both in pregnancy, as two separate supplements with different timings. Folic acid is 400 micrograms a day, ideally from 3 months before conception until 12 weeks. Vitamin D is 10 micrograms a day between early October and late March, and all year if you usually cover most of your skin outdoors, spend a lot of time indoors or have black or brown skin. Neither the NHS pregnancy page nor the NHS folic acid page lists vitamin D as something to avoid with folic acid. The BDA says a pregnancy-specific supplement providing 400 micrograms of folic acid also works, so if you choose one, check whether it includes the 10 micrograms of vitamin D you need and that it contains no vitamin A. A pharmacist or midwife can check what suits you. Don't take more than 100 micrograms of vitamin D a day. Our guide to vitamin D in a UK winter has more on the vitamin.

Can you take iron and folic acid together?

Yes, for most people. Neither the NHS folic acid page nor its iron tablet pages list the other as an interaction, and the World Health Organization recommends daily iron and folic acid together in pregnancy. In the UK, iron isn't routine in pregnancy: the NHS checks your iron with blood tests at booking and around 28 weeks, and your GP or midwife recommends iron if you need it. Take iron with water, too, because the NHS says tea, eggs and milk can affect how well it works. Keep iron tablets out of children's reach: the NHS warns iron can be very dangerous if a child takes it by accident. Our guide to iron tablets has more.

Where Natura fits

Natura doesn't make a folic acid tablet. Daily Folate, in the Natura cabinet (coming soon), is 400 µg of folate as L-5-methyltetrahydrofolate (methylfolate), which isn't the form the NHS pregnancy advice is built on; our guide to folate vs folic acid explains the difference. Folate contributes to normal blood formation and to the reduction of tiredness and fatigue. If you could get pregnant, take a 400 microgram folic acid supplement as the NHS advises; Daily Folate is with the daily bottles.