Vitamin B deficiency
Key facts
- Vitamin B deficiency happens when your body doesn't have enough vitamin B.
- Your body needs a certain amount of each type of vitamin B to function well.
- Severe vitamin B deficiency can cause diseases such as beriberi or pellagra.
- People who are vitamin B deficient may feel tired, numbness or weakness, among other symptoms.
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 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.
However, symptoms are usually mild and can be treated by having more food rich in B-vitamins.
Types of vitamin B deficiency: symptoms, effects and risk factors
Thiamin
Symptoms
- weight loss
- short-term memory loss and confusion
- muscle weakness
- cardiovascular symptoms
Effects
- Beriberi disease
- Wernicke–Korsakoff syndrome
Risk factors
- hazardous alcohol use
- liver disease
- malnutrition
- bariatric surgery
Riboflavin
Symptoms
- growth disturbances
- rash
- inflammation of your mouth and tongue
- cracks at the corner of your mouth
- anaemia
Effects
- Ariboflavinosis
Risk factors
- vegan diet
- vegetarian athletes
- pregnant and breastfeeding people and their babies
Niacin
Symptoms
- mainly affects the skin
- dementia
Effects
- Niacin deficiency — severe disease is called pellagra
Pantothenic acid
Symptoms
- irritable
- restless
- tiredness, apathy and malaise
- sleep disturbances
- nausea, vomiting and cramping
- numbness and staggering gait
Effects
- Pantothenic acid deficiency — only seen in individuals fed synthetic diets
Biotin
Symptoms
- rash
- conjunctivitis (pink eye)
- alopecia (hair loss)
- central nervous system abnormalities
Effects
- Biotin deficiency
Folate
Symptoms
- weakness and fatigue
- trouble concentrating
- irritability
- headaches
- heart palpitations
- shortness of breath
Effects
- Folate deficiency
Risk factors
- decreased intake — due to an eating disorder, older age, disability or isolation
- conditions resulting in malabsorption
- hazardous alcohol use
- smoking
- increased metabolic need — from rapid growth, pregnancy, burns, blood loss, damage to the gastrointestinal tract, some blood conditions
- medicines — such as methotrexate and sulfasalazine
Vitamin B12
Symptoms
- tired or weak
- pale skin
- heart palpitations
- loss of appetite
- weight loss
Effects
- Vitamin B12 deficiency
Risk factors
- autoimmune gastritis (pernicious anaemia)
- gastrectomy (stomach removal)
- small bowel resection
- bariatric surgery
- vegan diet
- intestinal disorders that may affect absorption — such as coeliac disease, inflammatory bowel disease
- medicines — metformin
In more severe cases, vitamin B deficiency can cause more serious problems.
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 plant milks
- some fortified meat substitute products
- some breakfast cereals
The B vitamins are water soluble. 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
It can make it harder for your body to absorb vitamins from food.
Vitamin B deficiency can also be caused by alcohol abuse. 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.
Complications of vitamin B deficiency
The complications of vitamin B deficiency depend on which B-vitamin you are lacking.
Severe anaemia can lead to tachycardia (fast heartbeat) and heart failure.
If you're pregnant, not having enough folate can increase the risk of your baby having a neural tube defect, such as spina bifida.
Folate deficiency can also increase your risk of some cancers.
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 24 hours a day, 7 days a week.
Learn more here about the development and quality assurance of healthdirect content.
Last reviewed: April 2024
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