What is vitamin B9 deficiency: symptoms, causes & prevention?

Vitamin B9, also called Folate, is essential in keeping our nerves and red blood cells healthy. Folate is acquired through diet and, as for vitamin B12, a deficiency can cause megaloblastic anaemia. A deficiency can cause your body to make abnormally large red blood cells that cannot function correctly (megaloblastic anaemia). Knowing your vitamin B9 level can help you ascertain whether action is needed. Vitamin B9 deficiency can be treated readily with diet changes and supplementation. However, sometimes complications that have emanated through longstanding deficiency cannot always be cured.

What is vitamin B9 deficiency?

Vitamin B9 deficiency refers to a level of vitamin B9 that is lower than the ‘normal’ recommended range. A deficiency in vitamin B9 can occur due to a poor diet not containing enough of this vitamin, or it can be the result of a condition affecting the body’s ability to absorb and/or process it, such as Coeliac or Crohn’s disease. Unfortunately, vitamin B9 deficiency can remain undetected for years and cause damage before it is diagnosed.

In order to avoid vitamin deficiency anaemia, it is recommended that your dietary intake of vitamin B9 is 200 micrograms per day.

What are the symptoms of vitamin B9 deficiency?

The symptoms of vitamin B9 deficiency are varied and may develop slowly and gradually over time. However, it is important to note that many people who have a vitamin B9 deficiency do not experience symptoms and the deficiency is detected through testing for it. Vitamin B9 deficiency can affect people of all ages, although it is more commonly seen in older people. The symptoms of B9 deficiency include:

  • Tiredness
  • Pins and needles
  • Muscle weakness
  • Mouth ulcers
  • Memory problems

What are the causes of vitamin B9 deficiency?

The main causes of vitamin deficiency include the following:

  • Poor or restricted diet: A healthy and balanced diet that contains a variety of fruit and vegetables should be sufficient to sustain an acceptable of vitamin B9 in the body. However, an unhealthy diet lacking folate-rich foods can lead to vitamin B9 deficiency. Overcooking food can also result in deficiency as it causes the vitamin content to diminish.
  • Gastrointestinal disorders: health conditions such as atrophic gastritis (chronic inflammation of the stomach lining), Crohn’s disease and Coeliac disease can affect your body’s ability to absorb and/or process vitamins.
  • Blood conditions: certain blood conditions such as sickle cell anaemia or spherocytosis mean your body needs more folate than normal and can result in a folate deficiency.
  • Liver damage: from drinking too much alcohol
  • Medications: certain drugs such as anti-seizure drugs, sulfasalazine and methotrexate can reduce the amount of vitamin B9 in the body or reduce the amount you’re the body can absorb.

How to prevent and treat vitamin B9 deficiency

Certain lifestyle changes can help prevent vitamin B9 deficiency. These include:

Diet modifications

Maintaining a healthy, balanced diet is essential to avoiding deficiencies and maintaining good health in general.  Most people can get the amount of folate they need through eating a healthy balanced diet. Vitamin B9 can be found in small amounts in many different foods, including:

  • Brussel sprouts
  • Broccoli
  • Leafy greens
  • Chickpeas, peas and kidney beans
  • Liver (to be avoided during pregnancy)

You can also opt for foods fortified in folic acids, such as some breakfast cereals. You can find out what foods are fortified in folic acids by reading food labels.


If you are found to have vitamin B9 deficiency you must discuss this with your GP. Usually, your GP will treat this with folic acid supplements for about 4 months.

It is recommended that pregnant women (and those trying to get pregnant) take 400 mcg of folic acid supplement before and during the first 12 weeks of pregnancy.

It is essential to have your vitamin B12 levels checked if your vitamin B9 levels are low. Treating a folate deficiency without treating a vitamin B12 deficiency can lead to serious complications including irreversible damage to the nervous system.

Quitting smoking

Some studies have found smoking can increase your chances of vitamin B9 deficiency as it interferes with the absorption of nutrients. Smoking is the leading cause of preventable death in the UK and contributes to lung cancer and coronary heart disease. If you are a smoker and want to quit the habit, you can find practical tips and advice here.

How can I raise my vitamin B9 levels fast?

Usually, people have their vitamin B9 deficiency treated by tablets. Rarely, they may need to have injections from their GP or a specialist in order to raise their levels quickly.

Is vitamin B9 deficiency serious?

Vitamin B9 deficiency can cause severe complications, which can include:

  • Megaloblastic anaemia, which causes your body to make abnormally large red blood cells that cannot function correctly. This leads to a lack of oxygen being circulated through the body.
  • Nerve damage, which can cause pins and needles, burning, tingling, or peripheral neuropathy
  • Increased risk of heart disease.
  • Neural Tube Defects, such as spina bifida and anencephaly, can develop in babies of women who are deficient in vitamin B9 while pregnant.

What is considered low vitamin levels?

The ‘normal’ range of vitamin B9 varies between laboratories. However, as a guide, the normal level of vitamin B9 is above 4.5μg/L.

How long does it take to recover from a vitamin B9 deficiency?

Once treatment begins, vitamin B9 deficiency symptoms normally improve within days or a few weeks. Vitamin deficiency can however cause permanent nerve damage, neurological issues, and debilitating tiredness.

How can I get my vitamin B9 levels tested?

At home

You can buy a single Bluecrest vitamin B9 home test kit to measure your levels quickly and easily. It consists of a simple finger prick test that takes minutes to do and you’ll get results in as little as 8 days. You will also get additional extras such as your own MyWellness results portal and 24/7 GP helpline access for a year.

At a clinic

Alternatively, you can get a vitamin B9 test as part of our more comprehensive Essential Energy and Fatigue plus package. It consists of an in-depth, face-to-face health check with a Health Assessment Specialist, which you can easily book online at one of over 2,000 mobile clinics available nationwide. You will receive a wide array of other key health markers and a detailed results report sent through the post.