B12 generally refers to vitamin B12. A deficiency of vitamin B12 in the body may result in skin, hematologic, neurological, and digestive symptoms, such as white spots, dry and flaky skin, mental confusion, nausea and vomiting. 1. Skin: widespread symmetrical hyperpigmentation, which is mainly concentrated in the palms of the hands, soles of the feet, nails and other parts of the body. If the body lacks vitamin B12 due to pernicious anemia, white spots and baldness may also appear. 2. Blood system: lack of B12 often may appear anemia face, that is, pale, dry skin peeling. 3. Nervous system: symptoms such as mental instability, dull expression and intellectual decline may occur. In serious cases, it may lead to dementia and hypotonia. 4. Digestive system: patients may experience nausea and vomiting, diarrhea, loss of appetite and other symptoms. If the above mentioned symptoms occur, it is necessary to go to the hospital in time to determine whether your body is deficient in vitamin B12.