6 mins read

What Is Folate and Vitamin B12 Deficiency Anaemia?

June 21, 2021


Vitamins arranged in the writing of "b12"

Blog Homepage >>

Vitamin B12 or folate deficiency anaemia occur when there is not enough of either nutrient, causing the body to produce abnormally large red blood cells which do not function properly.

Both nutrients are essential, so need to be acquired via diet, and are important for the normal development and function of red blood cells.

Let’s explore what B12 and folate deficiency anaemia are, the symptoms, causes and how it can be prevented or treated.

What is Vitamin B12 or folate deficiency anaemia?

Folate, also known as vitamin B9, and vitamin B12 are both vital for making and repairing DNA as well as producing healthy red blood cells [1]. They are complex B vitamins and help to keep the body working effectively.

Because neither B12 nor folate can be made by the body, they must be acquired through the diet. The body is unable to store lots of folate, so deficiency can occur within a few weeks, but most healthy people have enough vitamin B12 stored to last them 3-5 years. If the body becomes deficient in either of these vitamins, it is a sign that there is a chronic shortage.

Anaemia is a condition that is defined as a reduced number of red blood cells or a reduction in their quality. Although a lack of these nutrients in the diet can lead to deficiency, the most common cause of vitamin B12 deficiency in the UK is pernicious anaemia [2].

What is pernicious anaemia?

Pernicious anaemia is an autoimmune disorder where the body’s own immune cells attack the cells in the stomach that produce a protein in the stomach called intrinsic factor. Vitamin B12 combines with intrinsic factor so that it can be absorbed into the body via the distal ileum, a specific part of the gut.

However, by attacking the intrinsic factor producing cells in the stomach, vitamin B12 is unable to be absorbed. It isn’t known what causes it exactly but risk factors for pernicious anaemia include:

  • Women around 60 years of age
  • People with a family history of the condition
  • People who have other autoimmune disorders like Addison’s disease and vitiligo [3].

Vitamin B12 and folate deficiency symptoms

The symptoms caused by vitamin B12 and folate deficiency anaemia are wide-ranging. Often, they develop gradually over a long period of time, but if the condition is left untreated, they can become worse.

Because anaemia causes the body to produce fewer red blood cells or to have a lower concentration of haemoglobin – the protein responsible for transporting oxygen around the body – it is associated with some general symptoms, including:

  • fatigue
  • lethargy
  • feeling faint
  • headaches
  • shortness of breath
  • pale skin
  • heart palpitations
  • tinnitus
  • loss of appetite
  • weight loss
B12 & folate deficiency symptoms

Vitamin B12 Deficiency Symptoms

Vitamin B12 deficiency anaemia can also cause specific symptoms such as:

  • changes in the way you move
  • cognitive decline
  • depression
  • inflamed tongue
  • irritability
  • loss of taste
  • mouth ulcers
  • paranoia
  • pins and needles [4]

People who have vitamin B12 deficiency but not anaemia may also experience these symptoms.

Folate deficiency anaemia symptoms

Vitamin B9 or folate deficiency can also cause:

  • depression
  • diarrhoea
  • loss of taste
  • muscle weakness
  • pins and needles in hands and feet

Causes of vitamin B12 and B9 deficiency anaemia

There are a number of causes of vitamin B12 and B9 deficiency including poor diet, specific conditions such as pernicious anaemia, and certain medications.

Vitamin B12 deficiency causes

The most common cause of vitamin B12 deficiency is pernicious anaemia, an autoimmune condition affecting the stomach and preventing the absorption of vitamin B12 into the body.

However, that is not the only cause. A poor dietary intake of vitamin B12 also results in deficiency and there are certain groups who are more at risk. Vitamin B12 is naturally present in animal-based foods which means people who do not eat these foods, particularly vegans, are at risk of becoming deficient in vitamin B12 [6].

Other factors which can contribute to the development of vitamin B12 deficiency are:

  • Stomach conditions
    • Gastric bypass
    • Bariatric surgery
    • Total or partial gastrectomy (where part of the stomach is removed)
  • Intestinal conditions
    • Crohn’s disease
    • Inflammatory bowel disease
  • Certain medications
    • Metformin (for diabetes)
    • Stomach acid blockers or proton pump inhibitors (PPIs) [4]

Vitamin B9 deficiency causes

Vitamin B9 or folate deficiency can be caused by a poor diet where not enough foods rich in B9 are consumed, malabsorption of folate by the body and excessive urinating.

Vitamin B9 or folate is a water-soluble vitamin and for this reason, the body is unable to store it for long. Unlike vitamin B12, which the body has stored to last a few years, folate stores can be depleted within a few months. So, getting enough vitamin B9 into your diet is paramount.

B9 deficiency causes

A lack of dietary intake of folate is a major cause of folate deficiency anaemia. There are many good food sources of folate, including:

  • Brown rice
  • Chickpeas
  • Eggs
  • Green leafy vegetables
  • Legumes
  • Soybeans
  • Spinach
  • Wholemeal bread [2]

By eating a healthy and balanced diet, you will ensure your body is getting all the nutrients it needs to work effectively. People who tend to eat an unhealthy or unbalanced diet are at a greater risk of developing a deficiency. Alcohol can also reduce folate absorption and/or be a factor in poor dietary intake.

Other causes of folate deficiency include:

  • Coeliac disease
  • Medicines used to treat epilepsy
  • Cancer
  • Blood disorders
  • Infections
  • Pregnancy

Folate and pregnancy

As well as its role in red blood cell production, folate is also vital for the making and repairing of DNA. During pregnancy, there is a greater demand for the nutrient because of the increased growth and development of the foetus.

Folate deficiency during pregnancy has been associated with abnormalities in both mother and baby. Without adequate folate, babies can be born with neural tube defects [8]. So, it is vital that women who want to fall pregnant, take a folic acid 500 microgram tablet every day until they are 12 weeks pregnant [8].

Vitamin B12 deficiency treatment

Before treatment begins, it is best to find out what may be causing the deficiency. In most cases, it can be treated with supplements via tablets or injections.

For individuals, whose deficiency is diet-related, then it’s likely vitamin B12 tablets will be prescribed to be taken between meals. Alternatively, a twice-yearly injection of hydroxocobalamin, a type of B12, may be given. It’s also recommended to incorporate more vitamin B12 rich foods into the diet.

If vitamin B12 deficiency isn’t diet-related, then it is likely regular vitamin B12 injections will be required. These will be arranged and given by a healthcare professional depending on the severity of the symptoms.

Folate deficiency treatment

In most cases, people who are deficient in folate will be given folic acid tablets to increase their levels, as well as being advised to increase their dietary intake.

Monitoring B12 and B9 levels

You can monitor your own vitamin B12 and B9 levels at home using our Nutricheck home blood test.  Nutricheck not only checks your levels of these two key nutrients but also vitamin D which a lot of people in the UK are deficient in, especially during winter months. It also checks your body for other key nutrients, essential for overall wellbeing including iron, magnesium and cholesterol.

Learn more about vitamin deficiencies>>


Both vitamin B12 and B9 are essential for the normal development of red blood cells as well as the production and repair of DNA. Deficiency in these can disrupt these pathways and cause numerous side effects that can affect your everyday life.

Understanding what causes deficiencies in these nutrients and recognising the signs and symptoms is important so that the correct treatment can be applied.

Back To Blog >>

- Health scores calculated


Article references

  1. Fenech, M. (2012). Folate (Vitamin B9) and Vitamin B12 and Their Function in the Maintenance of Nuclear and Mitochondrial Genome Integrity. Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis: 733(1-2), pp 21-33.

  2. Allen, L, H. (2008). Causes of Vitamin B12 and Folate Deficiency. Food and Nutrition Bulletin: 29(2), pp S20-S34.

  3. Stabler, S, P. (2013). Vitamin B12 Deficiency. The New England Journal of Medicine: 3, pp 149-160.

  4. Kene, M, K AND Dhanawade, S. (2020). Clinicohematological Profile of Megaloblastic Anaemia. International Journal of Healthcare and Biomedical Research: 8(3), pp 52-57.

  5. Greenberg, J, A et al. (2011). Folic Acid Supplementation and Pregnancy: More Than Just Neural Tube Defect Prevention. Reviews in Obstetrics and Gynecology: 4(2), pp 52-59.

This information has been medically written by Dr Thom Phillips

Thom works in NHS general practice and has a decade of experience working in both male and female elite sport. He has a background in exercise physiology and has published research into fatigue biomarkers.

Dr Thom Phillips

Dr Thom Phillips

Head of Clinical Services