Vitamin B12 deficiency can lead to serious health problems, so it is very important to recognize the early warning signs of its deficiency. Here are five major warning signs that should not be ignored:

1. Fatigue and weakness:
   One of the first signs of vitamin B12 deficiency is usually a feeling of fatigue and exhaustion that is not explained by mere rest or good sleep. If you notice that you frequently feel extremely tired even after getting enough rest, this could be a sign of vitamin B12 deficiency.
2. Problems in memory and perception:
   Forgetfulness, difficulty concentrating, and sometimes confusion can be an indication of vitamin B12 deficiency, especially among older adults. In rare cases, people may mistake symptoms of this deficiency for the onset of dementia.
3. Changes in mood:
   Some studies have found that vitamin B12 deficiency can affect mood, including feeling depressed or anxious. This is thought to be due to the vitamin’s effect on levels of brain chemicals such as serotonin and dopamine.
4. Changes in sensation and numbness:
   People with vitamin B12 deficiency often experience numbness or tingling in the hands and feet or other times signs may include difficulty with balance and muscle weakness. These symptoms are due to the effect of deficiency on the nerves.
5. Problems in the tongue and mouth:
   Some changes may appear in the mouth that indicate a deficiency of vitamin B12, such as inflammation of the tongue that becomes smooth and red, or feeling pain when eating spicy food. Circular sores in the mouth may also be a sign of deficiency.

If you recognize one or more of these symptoms, it is important to consult a doctor. Vitamin B12 deficiency can be easily diagnosed with a blood test and treatment is often simple and effective and includes taking vitamin supplements and modifying the diet.