'I'm a dentist - the earliest and most notable symptoms of B12 deficiency show up in the mouth'

But a lack of international agreement on what counts as a deficiency leads to diagnosis difficulties and poor outcomes.

According to Manhattan dentist Sandip Sachar, the condition is characterised by four distinct symptoms in the early stages, all of which appear in the mouth.

Dental professionals often encounter a swollen, smooth tongue, cracks at the corners of the mouth and persistent mouth ulcers, as well as delayed healing following dental work.

"One of the earliest and most notable symptoms of vitamin B12 deficiency is glossitis," Sandip told GB News.

"Glossitis presents as a smooth and swollen tongue. Patients with B12 deficiency may present with the symptoms of a swollen tongue due to disruption of DNA synthesis in the rapidly dividing cells of the mucosal tissue."

Yet, despite hindering the life quality of patients, the symptoms often go unnoticed or get misdiagnosed as other ailments.

When B12 levels are suboptimal, the cells fail to mature properly, which leads to the thinning of the mucosal surface.

Over time, this causes the tongue surface to appear shiny and induces a burning sensation.

The corners of the mouth are also vulnerable because they are high-motion zones where the skin and mucous membranes meet, explaining why cracks in this area are also common.

Vitamin B12 also plays a crucial role in immune system function, which becomes less effective at fighting off infections when levels are low. This can often lead to slower healing times.

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Sandip warned: "The oral symptoms listed above related to B12 deficiency can significantly impact the patient's quality of life.

"They can make eating, drinking, and even speaking uncomfortable at times. This can lead to reduced appetite, altered nutrition, and weight loss.

"Some patients experience significant metallic or altered taste that can be very frustrating. These symptoms can also result in anxiety and fear due to the unknown reasons why they are experiencing these symptoms."

Prompt action is key here, as delays in treatment only fuel the risk of long-term complications down the line.