Vitamin B9 (folate) is a water-soluble vitamin that’s essential for your health. Your body doesn’t store vitamin B9 so you can become deficient in a matter of weeks. Vitamin B9 deficiency can lead to anaemia and might increase your risk of heart disease. It’s also really important during early pregnancy for a developing baby. Signs of deficiency include tiredness, weakness, shortness of breath, heart palpitations, and difficulty concentrating. If you’re deficient, you should eat folate-rich foods and you might also need to take a folic acid supplement.

What is folate?

Vitamin B9, also called folate or folic acid, is a type of B vitamin.

Folate is the naturally occurring form of vitamin B9. Folic acid is the synthetic version of vitamin B9, which is what is found in fortified foods and supplements.

You can check your vitamin B9 levels as part of a vitamins blood test.

Food sources of folate (vitamin b9) — spinach, broccoli, and avocados

What does vitamin B9 do?

Vitamin B9 plays an essential role in:

  • making and repairing your DNA
  • producing red blood cells — which carry oxygen around your body

Causes of vitamin B9 deficiency

Your body can’t build up a store of vitamin B9 so you can become deficient in a matter of weeks. So it’s important to continuously get enough from your diet or from supplements.

You might also be at an increased risk of vitamin B9 deficiency if you:

  • are pregnant
  • have a poor diet
  • drink excessive amounts of alcohol
  • take certain medications — like anticonvulsants and proton pump inhibitors (PPIs)
  • have a gastrointestinal disorder — like coeliac or Crohn’s disease
  • have a genetic disorder that stops your body from converting vitamin B9 to a form your body can use

Effects of vitamin B9 deficiency

Folate deficiency anaemia
You need vitamin B9 to make normal red blood cells, so if you’re deficient it can lead to megaloblastic anaemia — where your red blood cells aren't fully developed and larger than usual. This means you can’t transport enough oxygen around your body.

Neural tube defects
Vitamin B9 plays an essential role in the development of a baby’s brain and spinal cord during pregnancy. If you’re deficient, especially in the first few weeks of pregnancy, it might lead to a serious birth defect called a neural tube defect (NTD) — like spina bifida and anencephaly.

If you have low levels of vitamin B9 during pregnancy it might increase your risk of premature labour or your baby could have a low birth weight.

Heart disease
Vitamin B9 plays an important role in homocysteine metabolism. If you don’t have enough vitamin B9 to help metabolise and lower your homocysteine levels, it might increase your risk for heart disease.

Symptoms of vitamin B9 deficiency

The symptoms of vitamin B9 deficiency include:

  • tiredness
  • weakness
  • heart palpitations
  • shortness of breath
  • headaches
  • irritability
  • difficulty concentrating

If you have any of these symptoms it’s really important to test your levels.

How to test your vitamin B9 levels

You can check your vitamin B9 levels as part of a vitamins blood test. Your test kit contains everything you need to collect your sample at home. Our easy-to-follow instructions will guide you through it. Or, if you don't want to take your own blood sample, we can arrange for a nurse to collect it for you at a clinic at an extra cost.

How to treat vitamin B9 deficiency

Folic acid (vitamin B9) deficiency can be treated by increasing the amount of folate-rich foods you eat or by taking a folic acid supplement.

Folate-rich foods
Even if you're thinking of taking a folic acid supplement, including folate-rich foods in your diet is a good idea. These foods are full of other nutrients and are good for your overall health. Foods high in folate include:

  • leafy, green vegetables — for example, spinach, kale, broccoli, cabbage, and brussels sprouts
  • beans, peas, and lentils
  • eggs
  • shellfish
  • beetroot
  • oranges
  • wholegrains
  • avocado

Foods fortified with folic acid
Some foods, particularly some breakfast cereals, are fortified with folic acid. You’ll be able to see this on the food label.

The UK is planning to make it mandatory to fortify all flour-based products, like bread, with folic acid. This is to try to lower the risk of babies developing NTDs — which are in most cases preventable. This is commonly done in other countries and research shows that it’s very safe.

Folic acid supplements
For most people, taking a folic acid supplement for about four months is enough. You might need to continue taking them if your levels still aren’t back to normal after this.

If you’re a woman, it’s recommended that you take a 400 mcg folic acid supplement before and during the first 12 weeks of pregnancy. In some cases, you might need to take a higher dose. You should work with your health professional to work out the right dosage for you.

It’s also really important to make sure your vitamin B12 levels are normal when starting a folic acid supplement. This is because folic acid supplements can mask the symptoms of vitamin B12 deficiency. If vitamin B12 deficiency goes untreated, it can lead to irreversible damage to your nervous system.

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Morris, J. K., Rankin, J., Draper, E. S., Kurinczuk, J. J., Springett, A., Tucker, D., ... & Wald, N. J. (2016). Prevention of neural tube defects in the UK: a missed opportunity. Archives of Disease in Childhood, 101(7), 604-607.

Reynolds, E. (2006). Vitamin B12, folic acid, and the nervous system. The Lancet Neurology, 5(11), 949-960.

National Institue of Health (2018). Office of dietary supplements. Folate: Fact sheet for health professionals. Retrieved 23 October 2018 from