Vitamin B12 keeps your nerves and blood cells healthy, so when levels run low the effects can show up in unexpected places, including the way you speak. Speech changes are not the most common sign of B12 deficiency, but they are one of the more serious ones, because they suggest the nervous system is affected.
Can B12 deficiency cause speech problems?
Yes. A lack of vitamin B12 can affect speech in three ways:
- Loss of coordination. Untreated B12 deficiency can damage the nervous system and cause a loss of physical coordination called ataxia. This can affect the whole body and make speaking or walking difficult. Speech may sound slow, slurred or clumsy.
- Confusion and memory problems. B12 deficiency can cause problems with memory, understanding and judgment, and in more severe cases confusion. This can make speech hesitant or muddled, and it can become hard to find the right word or follow a conversation.
- A sore mouth. A sore, red tongue and mouth ulcers are common in B12 deficiency and can make talking uncomfortable.
These changes usually come on gradually, over weeks or months, and tend to appear alongside other symptoms.
Sudden speech problems are an emergency
Speech that becomes slurred or confused suddenly is not a vitamin problem until proven otherwise. It can be a sign of a stroke. Call 10177, or 112 from a cellphone, straight away if you notice:
- Face: one side of the face drooping, or difficulty smiling
- Arms: weakness or numbness in one arm, or not being able to lift both arms and keep them up
- Speech: slurred words, or sounding confused
Do not wait to see whether it passes. Stroke symptoms can stop after a short time and still need urgent medical attention.
Other symptoms of vitamin B12 deficiency
| General symptoms | Nerve and mood symptoms |
|---|---|
| Feeling weak or very tired | Pins and needles |
| Shortness of breath, palpitations | Numbness and muscle weakness |
| Headaches | Problems with balance and coordination |
| A sore or red tongue, mouth ulcers | Problems with memory, understanding and judgment |
| Loss of appetite, indigestion, diarrhoea | Depression, anxiety or confusion |
| Problems with vision | Incontinence |
Nerve symptoms can develop even when a blood count shows no anaemia, so a normal haemoglobin does not rule out B12 deficiency.
Who is most at risk of low B12?
- Adults over 50. Many produce less stomach acid, which is needed to absorb B12 from food.
- Vegans and vegetarians. B12 occurs naturally only in animal foods.
- People with pernicious anaemia, who cannot make the protein (intrinsic factor) needed to absorb B12.
- People on certain long-term medicines, including metformin for diabetes and acid-reducing medicines such as omeprazole.
- People who have had stomach or bowel surgery.
How is B12 deficiency diagnosed and treated?
Diagnosis is based on your symptoms and a blood test. Treatment depends on the cause:
- If your diet is the cause, your doctor may prescribe daily B12 tablets or an injection twice a year, together with advice on food sources.
- If you cannot absorb B12 properly, you will usually need B12 injections. These are given frequently at first and then every two to three months, often for life.
Early treatment matters. Most symptoms improve once B12 is replaced, but nerve problems that have been present for a long time can sometimes be permanent.
Foods that contain vitamin B12
Adults need about 2.4 micrograms a day. Good sources are meat, fish, poultry, eggs, milk and other dairy products. Liver and shellfish are among the richest. If you eat little or no animal food, look for fortified breakfast cereals, fortified soya products and yeast extract, and ask your doctor or pharmacist whether you should take a supplement.
When to see a doctor
- Your speech has become slower, slurred or more hesitant over weeks or months.
- You have pins and needles, numbness or balance problems.
- You are unusually tired, breathless or forgetful, especially if you are in one of the risk groups above.
- You have a sore, red tongue or mouth ulcers that keep coming back.
Ask for a blood test. Do not start high-dose supplements before you have been tested, because this can make the result harder to interpret.
This article is for general information and does not replace advice from your doctor.
Medically reviewed by the ASAIPA clinical team.
