Vitamin B9 (Folate and folic acid)

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By Nikola · Precision Nutrition L1 · Updated 5 November 2026

Vitamin B9 is the B vitamin your body needs for cell division, red blood cell formation and the growth of maternal tissue in pregnancy; folate is the form found naturally in food, and folic acid is the synthetic form used in supplements and fortified foods. EFSA sets a population reference intake (PRI) of 330 µg dietary folate equivalents (DFE) a day for adults, an adequate intake of 600 µg in pregnancy and a PRI of 500 µg while breastfeeding. Pulses such as lentils, chickpeas and beans, leafy greens, asparagus, peanuts and sunflower seeds are the richest everyday sources. If you could become pregnant, food alone is not the whole answer: the NHS recommends 400 micrograms of folic acid a day from before pregnancy until week 12.

What vitamin B9 does

Folate works closely with vitamin B12, which is why a lack of either one leads to the same blood problem, megaloblastic anaemia (NIH). The NHS sums up the two jobs people notice most: folate helps the body form healthy red blood cells and reduces the risk of neural tube defects, such as spina bifida, in unborn babies.

Folate vs folic acid. Same vitamin, different absorption. According to the NIH, at least 85% of folic acid is bioavailable when taken with food, against about 50% of food folate. Dietary folate equivalents correct for this: 1 µg DFE equals 1 µg of food folate or 0.6 µg of folic acid taken with food (0.5 µg on an empty stomach). So 400 µg of folic acid with a meal counts as about 670 µg DFE.

The EU allows these health claims for foods that are at least a source of folate (Regulation (EU) 432/2012):

• “Folate contributes to maternal tissue growth during pregnancy”
• “Folate contributes to normal amino acid synthesis”
• “Folate contributes to normal blood formation”
• “Folate contributes to normal homocysteine metabolism”
• “Folate contributes to normal psychological function”
• “Folate contributes to the normal function of the immune system”
• “Folate contributes to the reduction of tiredness and fatigue”
• “Folate has a role in the process of cell division”

How much you need a day

Group	EFSA reference intake	EFSA upper limit (folic acid and added folate forms)	For reference: NIH RDA
Men	330 µg DFE (PRI)	1,000 µg	400 µg DFE
Women	330 µg DFE (PRI)	1,000 µg	400 µg DFE
Pregnancy	600 µg DFE (AI)	1,000 µg	600 µg DFE
Breastfeeding	500 µg DFE (PRI)	1,000 µg	500 µg DFE
Children 1-3 years	120 µg DFE (PRI)	200 µg	–

Sources: EFSA (reference intakes; 2023 upper limit), NIH ODS. PRI = population reference intake, AI = adequate intake. The EFSA upper limit covers folic acid and the authorised methylfolate salts in supplements and fortified foods combined, not folate naturally present in food. The UK uses a lower 200 µg a day for adults (NHS).

Best food sources

Food	Folate, 100 g	Portion	Folate per portion
Lentils, boiled	181 µg	½ cup, 99 g	179 µg
Chickpeas, boiled	172 µg	½ cup, 82 g	141 µg
Black beans, boiled	149 µg	½ cup, 86 g	128 µg
Avocado, raw	81 µg	½ fruit, 100 g	81 µg
Sunflower seed kernels, dried	227 µg	¼ cup, 35 g	79 µg
Peanuts, raw	240 µg	28 g (1 oz)	68 µg
Spinach, raw	194 µg	1 cup, 30 g	58 µg
Broccoli, raw	63 µg	1 cup chopped, 91 g	57 µg
Brussels sprouts, raw	61 µg	1 cup, 88 g	54 µg
Asparagus, raw	52 µg	4 medium spears, 64 g	33 µg

Source: USDA FoodData Central, SR Legacy, checked 5 November 2026: lentils FDC 172421, chickpeas FDC 173757, black beans FDC 173735, avocado FDC 171705, sunflower seeds FDC 170562, peanuts FDC 172430, spinach FDC 168462, broccoli FDC 170379, Brussels sprouts FDC 170383, asparagus FDC 168389. All values are food folate (the records list no folic acid), so µg here equals µg DFE. Portions are USDA household measures or halves and quarters of them; values per portion are calculated and rounded.

Half a cup of cooked lentils covers more than half of the EFSA 330 µg, and chickpeas or beans are close behind. Raw spinach with avocado and sunflower seeds, or a side of broccoli, Brussels sprouts or asparagus, adds the rest. The NHS also lists peas and kale. Animal foods are modest: USDA gives 47 µg per 100 g for raw eggs and 26 µg for farmed salmon.

Deficiency: signs and who is at risk

The main clinical sign of folate deficiency is megaloblastic anaemia. The NIH lists weakness, fatigue, difficulty concentrating, irritability, headache, heart palpitations and shortness of breath; the NHS adds a sore and red tongue, mouth ulcers and pins and needles. The same picture can come from a lack of B12, so a blood test, not a guess, tells the two apart.

The NIH names these groups as more likely to fall short:

• People with alcohol use disorder.
• Women of childbearing age and pregnant women.
• People with malabsorptive disorders.
• People with the MTHFR 677C>T gene variant.

The NHS adds that anticonvulsants and proton pump inhibitors can reduce absorption of folate and B12, and stresses early diagnosis, because some problems from the deficiency can become permanent. Treatment is usually folic acid tablets, often for about 4 months.

Supplements: when they make sense

• Before and in early pregnancy. The clearest case. The NHS recommends 400 micrograms of folic acid every day from before pregnancy until week 12, or from the moment you find out, and notes that it is difficult to get enough folate for a healthy pregnancy from food alone. The US Food and Nutrition Board gives the same 400 µg advice to all women who could become pregnant (NIH).
• A higher dose for higher risk. The NHS says you will be advised a 5 mg dose if either parent has a neural tube defect or a family history of one, after a previous affected pregnancy, or with diabetes, anti-epilepsy medicine or anti-retroviral medicine for HIV.
• A diagnosed deficiency, treated as your doctor prescribes.

Forms. Most products use folic acid; some use 5-methyltetrahydrofolate (5-MTHF, methylfolate). The NIH says its bioavailability is the same as or greater than that of folic acid, but conversion factors for it have not been formally established. Outside pregnancy planning and diagnosed deficiency, food comes first: pulses and greens cover the reference intake without pills.

Who should be careful

• Anyone who may be low in B12, especially older people. High doses of folic acid can correct the anaemia of B12 deficiency but not the nerve damage (NIH). The NHS warns that more than 1 mg (1,000 micrograms) a day can mask B12 deficiency, which, if missed, can damage the nervous system. EFSA based its 1,000 µg upper limit on this risk.
• People on methotrexate. The NIH advises patients taking methotrexate for cancer to consult their oncologist before taking folate supplements.
• People on antiepileptic medicines. These can lower blood folate, and the NIH advises checking with a healthcare provider before taking folate supplements.
• People on sulfasalazine. It inhibits folate absorption and can cause deficiency (NIH).
• Cancer history. The NIH calls the effect of supplemental folic acid on cancer risk unclear, especially after colorectal adenomas or cancer; EFSA (2023) found the evidence insufficient to show a causal link with colorectal or prostate cancer. Ask your doctor before high doses.

FAQ

What is the difference between folate and folic acid?

Folate is the natural form of vitamin B9 in foods such as lentils, spinach and asparagus. Folic acid is the synthetic form in supplements and fortified foods, and the body absorbs it better: at least 85% with food, against about 50% for food folate (NIH). Both count, measured in dietary folate equivalents.

How much folic acid should I take when trying to get pregnant?

The NHS recommends 400 micrograms of folic acid a day from before pregnancy until week 12. Women at higher risk of neural tube defects, for example with diabetes, a previous affected pregnancy or anti-epilepsy medicine, are advised a 5 mg dose by their doctor.

Which foods are highest in folate?

Pulses lead per portion: half a cup of cooked lentils has about 179 µg and chickpeas about 141 µg (USDA). Raw spinach, sunflower seeds, peanuts, avocado, broccoli, Brussels sprouts and asparagus are good sources too.

Related entries and articles

• Lentils, chickpeas and kidney beans
• Spinach, asparagus and avocado
• Vitamin B12 – the partner vitamin of folate
• Vitamin B6 and iron
• Warm lentil salad with roasted carrots and feta
• Chickpea and sweet potato curry
• Bob chorba: Bulgarian white bean soup

Sources

1. USDA FoodData Central, SR Legacy: lentils, boiled (FDC 172421); chickpeas, boiled (FDC 173757); black beans, boiled (FDC 173735). fdc.nal.usda.gov
2. USDA FoodData Central, SR Legacy: avocados, raw (FDC 171705); sunflower seed kernels, dried (FDC 170562); peanuts, raw (FDC 172430). fdc.nal.usda.gov
3. USDA FoodData Central, SR Legacy: spinach, raw (FDC 168462); broccoli, raw (FDC 170379); Brussels sprouts, raw (FDC 170383); asparagus, raw (FDC 168389); egg, whole, raw (FDC 171287); salmon, Atlantic, farmed, raw (FDC 175167). fdc.nal.usda.gov
4. EFSA NDA Panel. Scientific Opinion on Dietary Reference Values for folate. EFSA Journal 3893. efsa.europa.eu
5. EFSA NDA Panel (2023). Scientific opinion on the tolerable upper intake level for folate. EFSA Journal 21(11):e08353. efsa.europa.eu
6. EFSA: Overview on Tolerable Upper Intake Levels as derived by the SCF and the EFSA NDA Panel, version 11 (August 2025). efsa.europa.eu
7. NIH Office of Dietary Supplements: Folate, Fact Sheet for Health Professionals. ods.od.nih.gov
8. NHS: Vitamins and minerals – B vitamins and folic acid. nhs.uk
9. NHS: Vitamins, supplements and nutrition in pregnancy. nhs.uk
10. NHS: Vitamin B12 or folate deficiency anaemia. nhs.uk
11. Commission Regulation (EU) No 432/2012 – permitted health claims. legislation.gov.uk

This page is for information only and is not medical or dietary advice.