Vitamin B9 Deficiency

You’ll probably know Vitamin B9 more commonly as either folic acid or folate.

It is a vitamin which is required to ensure our DNA is made properly. Folate can be acquired from our diet particularly green leafy vegetables.

Anyone can suffer from folate deficiency, but it can be particularly harmful in pregnant women particularly to their unborn baby.

If we don’t consume enough B9 in our diet, then it can lead to deficiency which can lead to many health consequences.

Vitamin B9 deficiency and deficiency of Vitamin B12 are the most common types of vitamin deficiency. Both can lead to impaired cognitive ability and megaloblastic anaemia.

The metabolism of both vitamins therefore is linked, due to the similarity in their manifestations. Together they work to make red blood cells, essential for transporting oxygen around the body, and also help to keep several body systems healthy e.g. the cardiovascular, the nervous and the digestive.

If left untreated B9 deficiency can lead to megaloblastic anaemia, where the red cells are abnormal in their shape. Furthermore, often when neurological symptoms are present there is a chance that B9 deficiency is present with B12 deficiency also.

Who is at risk?

In effect every body is at risk of developing Vitamin B9 deficiency. However, there are some groups who are at a higher risk than others. These may include:

  1. Pregnant women
  2. Anyone who consumes large amounts of alcohol
  3. Anyone who continuously eats overcooked foods

You can detect vitamin deficiencies by carrying out a simple blood test alongside a patient history. The history may include what you eat or drink, family history of anaemia etc. Together these will determine if you have anaemia and what type.

Symptoms of Vitamin B9 Deficiency

If folate deficiency isn’t suspected and is allowed to progress, then many symptoms can arise as a result including:

Nervous system

  • Memory loss
  • Nerve damage
  • Depression
  • Psychosis
  • Visual defects

Muscular system

  • Muscle cramps can lead to trouble walking
  • Ankle swelling

Other symptoms

  • Gum disease
  • Burning sensation in the mouth
  • Cancer
  • Heart disease

Folate and Pregnancy

Generally, vitamin B9 is an umbrella term for synthetic folic acid. As humans are not able to make their own folate we must acquire it from our diet. Folate is necessary for both cell division and cell maintenance and plays key roles in DNA synthesis.

A run down of DNA and Folate
In short DNA is a code made up of 4 bases

These bases are:

  • Adenine (A)
  • Guanine (G)
  • Cytosine (C)
  • Thymine (T)

These bases pair up with each other to form base pairs

  • A with T
  • And G with C

Each base is connected to a sugar molecule and a phosphate molecule

Together these are called a nucleotide

Nucleotides are arranged in 2 long strands forming a spiral known as a double helix

This is the ladder shape associated with DNA

Folate plays a role in the creation of nucleotides

  • Needed for the building or repair of DNA

Folate also aids in the addition of a methyl group to the base cytosine

  • Methylation is essential for our normal development

Required for the methylation of the amino acid homocysteine to methionine

  • Impaired homocysteine and folate deficiency can lead to cardiovascular disease and neural tube defects in babies

Every woman who is trying to get pregnant should take folic acid supplements until the 12th week of pregnancy. The recommended dosage is 400 micrograms of folic acid every day. As we have seen folate is vital in DNA synthesis and this is important during the development of the foetus. During pregnancy it can prevent neural tube defects such as spina bifida.

Spina bifida is a group of birth defects resulting in the incomplete closure of the spinal column. This leads to the herniation or the exposure of the spinal cord. However, the supplementation of folic acid can reduce the prevalence of these birth defects.

Sources of Vitamin B9

Folate is found in several foods such as:


Dark green leafy vegetables

  • Avocado
  • Beetroot
  • Brussel sprouts
  • Asparagus
  • Spinach


Oranges/orange juice



Dairy products

  • Cheese
  • Yoghurt


Oily fish

Dietary supplements

  • Folic acid
  • Multivitamins
  • Pregnant women should try to avoid multivitamins containing vitamin A

Causes of Vitamin B9 Deficiency

The causes of vitamin B9 deficiency are relatively similar to the causes of B12 deficiency:

Pernicious anaemia

  • Where the immune system attacks the healthy cells in the stomach so contributes to the body’s inability to absorb certain vitamins


There are several medications which can interrupt the absorption of vitamins including B9, these include:

  • Anticonvulsants
  • Proton pump inhibitors
  • Metformin

Lack of Dietary Intake

Probably, the most common cause of vitamin B9 deficiency is a lack of dietary intake. Humans are unable to synthesise their own B9 so are reliant on acquiring what they need from their diet. This may result from not eating enough fruit and vegetables, which have other major health benefits and are not just a good source of vitamin B9.

Therefore, just like vitamin B12 deficiency the prevalence of vitamin B9 deficiency is higher in the older population. Around 1 in 20 aged 65-74 and 1 in 10 people over the age of 75.


Inflammatory bowel disease (IBD) such as Crohn’s disease can also have an effect of vitamin B9 status. Studies have shown that people with IBD have lower serum folate levels than those without disease. However, this could be due to a number of factors such as insufficient dietary intake, increased utilisation of B9 or may even be caused by the effects of medications.

Bariatric Surgery

Increases in the surgical treatment of obesity have led to deficiency of some vitamins in those patients. However, operations such as gastric banding can lead to the malabsorption of some vitamins. In the case of vitamin B9, some studies have shown that it is less prevalent than deficiency of vitamin B12, but around 20% of patients become deficient in B9. A lack of dietary intake mainly explains deficiency. This is because even if most of its absorption takes place in the small intestine, it can be absorbed throughout the whole of the intestinal system.


A good way to resolve the symptoms of vitamin B9 deficiency is to increase your intake through your diet. Increasing for example your consumption of fruit and vegetables can be a good way to increasing your B9 levels.

However, your GP may also prescribe folate tablets/supplements for around 4 months depending on the severity. If the folate anaemia continues then this may mean you have to take folate tablets for the rest of your life.

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Having always been intrigued by how body’s work, both in their day to day functions and also when things go wrong, Leanne is pursuing her passion for health. By combining her undergraduate degree in Biomedical Science and a Masters in Science communication with her love for writing, she is passing on her knowledge to Health Hub readers. Leanne strongly believes that science and health are something that should be talked about more and she hopes her articles will enable such conversations.