Vitamin B12 or folate deficiency anaemia - Causes (2024)

Vitamin B12 or folate deficiency anaemia occurs when a lack of either of these vitamins affects the body's ability to produce fully functioning red blood cells.

Red blood cells carry oxygen around the body. Most people withvitamin B12 or folate deficiency anaemia have underdeveloped red blood cells that arelarger than normal. The medical term for this is megaloblastic anaemia.

A vitamin B12 or folate deficiency can be the result of a variety of problems.

Causes of vitamin B12 deficiency

Pernicious anaemia

Pernicious anaemia is the most common cause of vitamin B12 deficiency in the UK.

Pernicious anaemia is an autoimmune condition that affects your stomach.

An autoimmune condition meansyourimmune system, the body's natural defence system that protects against illness and infection, attacks your body's healthy cells.

Vitamin B12is combined withaprotein called intrinsic factor in your stomach. This mix of vitamin B12 and intrinsic factor is then absorbed into the body in part of the gut called the distal ileum.

Pernicious anaemia causes your immune system to attack the cells in your stomach that produce the intrinsic factor, which meansyour body is unable to absorb vitamin B12.

The exact causeof pernicious anaemia is unknown, but it's more common inwomen around 60 years of age, people with a family history of the condition and those with another autoimmune condition, such asAddison's disease orvitiligo.

Diet

Some people can develop a vitamin B12 deficiency as a result of not getting enough vitamin B12 from their diet.

A diet that includes meat, fish and dairy products usually provides enough vitamin B12, but people who do not regularly eat these foodscan become deficient.

People who eat a vegan diet and do not take vitamin B12 supplements or eat foods fortified with vitamin B12, are also at risk.

Stores of vitamin B12 in the body canlastaround 2 to 5 years without being replenished, so it can take a long time forany problems to develop after a dietary change.

Conditions affecting the stomach

Some stomach conditions or stomach operations can prevent the absorption ofenough vitamin B12.

For example, agastrectomy, a surgical procedure where part of your stomach is removed, increases your risk of developing a vitamin B12 deficiency.

Conditions affecting the intestines

Some conditions that affect your intestinescan alsostop you absorbing the necessary amount of vitamin B12.

For example, Crohn's disease,a long-term condition that causes inflammation of the lining of the digestive system, can sometimes mean your body does notget enough vitamin B12.

Medicines

Some types of medicine can lead to a reduction inthe amount of vitamin B12 in your body.

Examples include:

• proton pump inhibitors (PPIs)
• metformin
• nitrous oxide

Your GP will be aware of medicines that can affect your vitamin B12 levels and will monitor you if necessary.

Functional vitamin B12 deficiency

Some people can experience problems related to a vitamin B12 deficiency, despite appearing to have normal levels of vitamin B12 in their blood.

This can happen as the result of a problem known as functional vitamin B12 deficiency, where there's a problem with the proteins that help transport vitamin B12 between cells.

This results inneurological complications involving the spinal cord.

Causes of folate deficiency

Folate dissolves in water, which means your body is unable to store it for long periods of time.

Your body's store of folate is usually enough to last 4 months. This means you need folate in your daily diet to ensure your body has sufficient stores of the vitamin.

Like vitamin B12 deficiency anaemia, folate deficiency anaemia can develop for a number of reasons.

Diet

Goodsources of folate includebroccoli, Brussels sprouts, asparagus, peas, chickpeas and brown rice.

If you do not regularly eat these types of foods, you may develop a folate deficiency.

Folate deficiency caused by a lack of dietary folate is more common in people who have a generally unbalanced and unhealthy diet, people who regularly misuse alcohol, and people following a restrictive diet that does not involve eating good sources of folate.

Malabsorption

Sometimes your body may be unable to absorb folate as effectively as it should. This is usually caused by an underlying condition affecting your digestive system, such ascoeliac disease.

Excessive peeing

You may lose folate from your body if you pee frequently.

This can be caused by an underlying condition that affects one of your organs, such as:

• congestive heart failure–where the heart is unable to pump enough blood around the body
• acute liver damage–often caused by drinking excessive amounts of alcohol
• long-termdialysis–where a machine that replicates the kidney function is used to filter waste products from the blood

Medicine

Some types of medicines reduce the amount of folate in your body or make the folate harder to absorb.

These include someanticonvulsants (medicines used to treat epilepsy), colestyramine, sulfasalazine and methotrexate.

Your GP will be aware of medicines that can affect your folate levels and will monitor you if necessary.

Other causes

Your body sometimes requires more folate than normal. This can cause folate deficiencyif you cannot meet your body's demands for the vitamin.

Your body may need more folate than usual if you:

• are pregnant – read more about complications of folate deficiency in pregnancy
• havecancer
• have a blood disorder–such assickle cell anaemia, an inherited blood disorder that causes red blood cells to develop abnormally
• are fighting an infection or health condition that causes inflammation (redness and swelling)

Premature babies (born before the 37th weekof pregnancy) are also morelikely to develop a folate deficiency because their developing bodies require higher amounts of folate than normal.