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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.
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.
The most common type of vitamin B deficiency in Australia is vitamin B12 deficiency.
Other more common types of vitamin B deficiency include:
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:
You are at higher risk of vitamin B12 deficiency if you:
If untreated, vitamin B12 deficiency may cause:
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:
People who are at an increased risk of folate deficiency include:
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 supports red blood cell production, immune function, and brain health.
Symptoms of vitamin B6 deficiency may include:
Groups of people at higher risk of vitamin B6 deficiency include:
Severe deficiency can result in neuropathy or, rarely, seizures (particularly in infants).
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:
Some people are at higher risk of thiamine deficiency, such as:
If untreated, thiamine deficiency can lead to:
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:
Risk factors for riboflavin deficiency include:
Complications of riboflavin deficiency are usually mild and reversible with treatment.
The rarer types of vitamin B deficiency include:
These are all rare in developed countries like Australia.
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:
Some people are at higher risk of niacin deficiency, such as:
If untreated, pellagra can be life-threatening.
Pantothenic acid plays a role in hormone synthesis and energy metabolism.
Pantothenic acid deficiency is extremely rare.
Reported symptoms (in rare cases) include:
Pantothenic acid deficiency is generally only seen in people on synthetic (formula-based) diets.
Biotin supports healthy skin, hair, and metabolism. True biotin deficiency is uncommon.
Possible symptoms of biotin deficiency include:
Risk factors for biotin deficiency include:
Symptoms of biotin deficiency are typically reversible with treatment.
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:
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.
You are at greater risk of vitamin B deficiency if you have changes to your gastrointestinal tract from:
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.
If you think you might be at risk of vitamin B deficiency, speak with your doctor or an accredited dietitian.
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.
Vitamin B deficiency is treated with doses of whichever vitamin is lacking. This may be given by:
Your doctor may want to see you again after 3 months to see if the treatment has worked.
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.
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:
Limiting alcohol intake and seeking medical advice if you are concerned about vitamin B deficiencies can help prevent complications.
See the Australian Guide to Healthy Eating (Opens in new tab).
The Dietitians Australia website (Opens in new tab) 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.
The Australian Guide to Healthy Eating (Opens in new tab) is also available in several community languages.
Australian Indigenous HealthInfoNet (Opens in new tab) has many resources about healthy eating for Aboriginal and/or Torres Strait Islander peoples.
Find out how we develop and review our content.
Last reviewed: February 2026




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