What is vitamin B deficiency?

Vitamin B deficiency happens when your body doesn't get enough vitamin B. This may happen if you don't eat enough foods containing vitamin B or because of a health condition.

Your body needs a certain amount of each type of vitamin to function well. The different types of vitamin B are all water-soluble (dissolve in water). This means that they mostly cannot be stored in the body and must be eaten regularly to avoid deficiency.

Find out more about vitamin B and your health.

What are the symptoms of vitamin B deficiency?

Symptoms of vitamin B deficiency differ, depending on which type of vitamin B you don't have enough of.

Symptoms are usually mild at first and can be treated by eating more foods rich in B vitamins.

In more severe cases, vitamin B deficiencies can cause serious or life-threatening health problems.

Common types of vitamin B deficiency

The most common type of vitamin B deficiency in Australia is vitamin B12 deficiency.

Other more common types of vitamin B deficiency include:

• vitamin B9 (folate) deficiency
• vitamin B6 (pyridoxine) deficiency
• vitamin B1 (thiamine) deficiency
• vitamin B2 (riboflavin) deficiency

Vitamin B12 (Cobalamin) deficiency

Vitamin B12 is required for red blood cell production and neurological function. It is the most common B vitamin deficiency in Australia.

Symptoms can affect both blood and nerves. Common symptoms include:

• fatigue and weakness
• anaemia
• numbness or tingling in the hands and feet
• memory problems or balance difficulties

You are at higher risk of vitamin B12 deficiency if you:

• are an older adult
• follow a vegetarian or vegan diet
• have pernicious anaemia
• take certain medicines such as metformin or a proton pump inhibitor
• have had bariatric surgery

If untreated, vitamin B12 deficiency may cause:

• permanent nerve damage
• cognitive impairment
• significant anaemia

Vitamin B9 (Folate) deficiency

Folate is essential for making DNA and red blood cells. In Australia, deficiency has decreased since it has become mandatory to fortify bread flour with folic acid.

Symptoms of folate deficiency commonly relate to anaemia. These include:

• fatigue
• pallor
• shortness of breath
• mouth ulcers

People who are at an increased risk of folate deficiency include:

• pregnant people (due to increased folate requirements)
• individuals with alcohol dependence
• people with malabsorption conditions such as coeliac disease
• individuals with restrictive diets

Anaemia is a possible complication of folate deficiency.

In pregnancy, there is an increased risk of neural tube defects such as spina bifida if folate intake is insufficient in the first trimester. This is why it is recommended to take a prenatal vitamin for at least 1 month before trying to conceive and to start taking one immediately after finding out about your pregnancy if not already taking a prenatal vitamin.

Vitamin B6 (Pyridoxine) deficiency

Vitamin B6 supports red blood cell production, immune function, and brain health.

Symptoms of vitamin B6 deficiency may include:

• irritability or mood changes
• cracked lips or mouth sores
• anaemia
• numbness or tingling in the extremities

Groups of people at higher risk of vitamin B6 deficiency include:

• people with alcohol dependence
• people with chronic kidney disease
• those taking certain medicines such as isoniazid
• individuals with poor dietary intake
• people with malabsorption conditions

Severe deficiency can result in neuropathy or, rarely, seizures (particularly in infants).

Vitamin B1 (Thiamine) deficiency

Thiamine is required for energy production and normal brain, nerve, and heart function. Deficiency is uncommon in Australia but still occurs in high-risk groups.

Common symptoms of thiamine deficiency include:

• fatigue and weakness
• reduced appetite
• numbness or tingling in the hands and feet
• confusion or memory changes (in more severe cases)

Some people are at higher risk of thiamine deficiency, such as:

• individuals with heavy alcohol use
• those with prolonged vomiting (for example, pregnant people with hyperemesis gravidarum)
• people who have had bariatric surgery
• individuals with severe malnutrition

If untreated, thiamine deficiency can lead to:

• peripheral neuropathy (dry beriberi)
• heart failure (wet beriberi)
• Wernicke's encephalopathy, a medical emergency affecting the brain
• Korsakoff syndrome, a permanent cognitive and memory disorder resulting from untreated Wernicke's encephalopathy

Vitamin B2 (Riboflavin) deficiency

Riboflavin supports energy production and skin and mucosal health. True deficiency is uncommon in Australia.

Symptoms of riboflavin deficiency often affect the skin and mouth. These include:

• cracks at the corners of the mouth (angular cheilitis)
• a sore or smooth tongue (glossitis)
• dry, scaly skin
• sensitivity to light

Risk factors for riboflavin deficiency include:

• limited or restrictive diets, especially diets that avoid milk products

Complications of riboflavin deficiency are usually mild and reversible with treatment.

Rarer types of vitamin B deficiency

The rarer types of vitamin B deficiency include:

• vitamin B3 (Niacin) deficiency
• vitamin B5 (Pantothenic acid) deficiency
• vitamin B7 (Biotin) deficiency

These are all rare in developed countries like Australia.

Vitamin B3 (Niacin) deficiency

Niacin is important for energy metabolism and nervous system function. Severe deficiency causes pellagra, which is now rare in Australia.

Symptoms of niacin deficiency include:

• a sun-exposed skin rash
• diarrhoea
• cognitive changes or confusion

Some people are at higher risk of niacin deficiency, such as:

• individuals with severe malnutrition
• people with chronic alcohol dependence
• individuals with certain metabolic disorders such as Crohn’s disease

If untreated, pellagra can be life-threatening.

Vitamin B5 (Pantothenic acid) deficiency

Pantothenic acid plays a role in hormone synthesis and energy metabolism.

Pantothenic acid deficiency is extremely rare.

Reported symptoms (in rare cases) include:

• headache
• fatigue, irritability or restlessness
• nausea, vomiting or cramping
• burning or tingling sensations in the feet

Pantothenic acid deficiency is generally only seen in people on synthetic (formula-based) diets.

Vitamin B7 (Biotin) deficiency

Biotin supports healthy skin, hair, and metabolism. True biotin deficiency is uncommon.

Possible symptoms of biotin deficiency include:

• hair thinning
• scaly skin rash
• fatigue
• low mood

Risk factors for biotin deficiency include:

• long-term use of certain anti-seizure medications or antibiotics
• long-term consumption of raw egg whites
• prolonged intravenous nutrition (TPN) without supplementation
• rare inherited metabolic disorders such as biotinidase deficiency

Symptoms of biotin deficiency are typically reversible with treatment.

What causes vitamin B deficiency?

You may be at risk of vitamin B deficiency if you don't include enough vitamin B in your diet.

The Australian Dietary Guidelines advise people with a vegan diet to take a vitamin B12 supplement. This is because vitamin B12 deficiency is more common in this group of people. If you are vegan, the only reliable sources of vitamin B12 are fortified foods (where vitamins have been added during processing), for example:

• fortified plant milks
• some fortified meat substitute products
• some breakfast cereals

The B vitamins are soluble in water. This means that they are not stored in your body, so deficiency can occur quickly if your intake is low.

Risk factors for vitamin B deficiency

You are at greater risk of vitamin B deficiency if you have changes to your gastrointestinal tract from:

• conditions — such as coeliac disease or Crohn's disease
• surgery to your small intestine

This can make it harder for your body to absorb vitamins from food.

Vitamin B deficiency can also be caused by heavy alcohol use. Your liver needs more vitamin B to metabolise (break down) the excess alcohol.

In some cases, deficiency of one type of B vitamin can cause a deficiency in another type. This is because they need each other to function properly.

When should I see my doctor?

If you think you might be at risk of vitamin B deficiency, speak with your doctor or an accredited dietitian.

FIND A HEALTH SERVICE — The Service Finder can help you find doctors, pharmacies, hospitals and other health services.

How is vitamin B deficiency diagnosed?

Your doctor will ask you about your symptoms and may examine you. They may also want to know about your diet, whether you drink alcohol and if you smoke.

They may arrange for you to have some blood tests.

Your doctor may give you nutrition advice or refer you to an accredited dietitian.

How is vitamin B deficiency treated?

Vitamin B deficiency is treated with doses of whichever vitamin is lacking. This may be given by:

• injection
• tablet
• liquid
• nose gels or sprays

Your doctor may want to see you again after 3 months to see if the treatment has worked.

What are the complications of vitamin B deficiency?

The complications of vitamin B deficiency depend on which B vitamin you are lacking.

These may include anaemia, nerve damage, heart problems or neurological changes.

Can vitamin B deficiency be prevented?

In Australia, almost all vitamin B deficiencies can be prevented with a balanced diet and targeted supplementation when needed. Higher risk groups who may require supplements or monitoring include:

• people planning pregnancy or who are pregnant
• vegetarians and vegans
• older adults
• people who have an excessive alcohol intake
• people with gastrointestinal conditions or after bariatric surgery
• those taking certain medicines

Limiting alcohol intake and seeking medical advice if you are concerned about vitamin B deficiencies can help prevent complications.

Resources and support

See the Australian Guide to Healthy Eating.

The Dietitians Australia website allows you to search for an Accredited Practising Dietitian.

You can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available to speak with you 24 hours a day, 7 days a week.

Languages other than English

The Australian Guide to Healthy Eating is also available in several community languages.

Information for Aboriginal and/or Torres Strait Islander peoples

Australian Indigenous HealthInfoNet has many resources about healthy eating for Aboriginal and/or Torres Strait Islander peoples.