Sores around the mouth or ulcers inside it can be a sign of vitamin B12 deficiency.
The sores can appear at the corner of the mouth and may appear at the edge of the lip.
These are not blisters, but raw areas that come and go.
Mouth ulcers — also known as canker sores — are small shallow lesions inside the mouth that can make eating painful.
They are not usually serious and often clear up within a week or two.
However, they can be a sign that vitamin B12 levels are low.
Other common signs of vitamin B12 deficiency include a lower appetite, headaches, a feeling of tiredness or depression and feeling breathless after minimal exercise.
One study has found that taking vitamin B12 supplementation can reduce mouth ulcers and the pain associated with them.
For the study, 58 people with mouth ulcers either took vitamin B12 supplements or a placebo for six months.
Three-quarters of people who took the vitamin were free of ulcers by the end of the study.
Only 32% of people who took a placebo were free of ulcers over the same period.
The authors explain the results:
“The average outbreak duration and the average number of ulcers per month decreased in both groups during the first four months of the trial.
However, the duration of outbreaks, the number of ulcers, and the level of pain were reduced significantly at five and six months of treatment with vitamin B12, regardless of initial vitamin B12 levels in the blood.
During the last month of treatment a significant number of participants in the intervention group reached ‘no aphthous ulcers status’”
Vitamin B12 deficiency is easy to rectify with supplements or by dietary changes.
The body uses vitamin B12 to make red blood cells and to keep the nervous system healthy.
Vitamin B12 levels can be boosted through supplementation or by eating foods such as dairy, liver, salmon and eggs.
Fortified breakfast cereals also contain vitamin B12.
The study was published in The Journal of the American Board of Family Medicine (Volkov et al., 2009).