why is vitamin a deficiency common in developing countries
Vitamin A deficiency The major cause is roughage which include few animal sources of pre-formed vitamin A.[citation needed] In addition to dietary problems, there are other causes of VAD. Iron deficiency can affect vitamin A uptake. Excess alcohol consumption can deplete vitamin A, and a stressed liver may be more susceptible to vitamin A toxicity. People who consume large amounts of alcohol should seek medical advice before taking vitamin A supplements. In general, people should also seek medical advice before taking vitamin A supplements if they have any condition associated with fat malabsorption such as pancreatitis, cystic fibrosis, tropical sprue and biliary obstruction. Other causes of Vitamin A deficiency are inadequate intake, fat malabsorption, or liver disorders. Deficiency impairs immunity and hematopoiesis and causes rashes and typical ocular effects (e.g., xerophthalmia, night blindness).[17]
Beriberi Beriberi refers to symptoms caused by thiamine (vitamin B1) deficiency. Beriberi has conventionally been divided into three separate entities, relating to the body system mainly involved (peripheral nervous system or cardiovascular) or age of person (like infantile). Beriberi is one of several thiamine-deficiency related conditions, which may occur concurrently, including Wernicke's encephalopathy (mainly affecting the central nervous system), Korsakoff's syndrome (amnesia with additional psychiatric manifestations), and Wernicke–Korsakoff syndrome (with both neurologic and psychiatric symptoms).