Infection, inflammation & Vitamin deficiencies
Bacterial, viral and fungi infections in the throat, mouth, gums and teeth can cause alteration in taste sensation. This causes swelling which reduces the flow of blood to taste buds and can synthesize substances that reduces the sensitivity of taste buds.
Deficiency in B vitamins such as B12 and zinc can cause dysgeusia. When vitamin B12 [2] is absent in daily diet it causes metallic taste and reduces the sensitivity of the taste buds [3]. When dysgeusia is caused by inadequate vitamin B12, it can be reversed when it is sufficiently added to diets.