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]
Thiamine deficiency Thiamine deficiency is a medical condition of low levels of thiamine (vitamin B1).[1] A severe and chronic form is known as beriberi.[1][5] There are two main types in adults: wet beriberi, and dry beriberi.[1] Wet beriberi affects the cardiovascular system resulting in a fast heart rate, shortness of breath, and leg swelling.[1] Dry beriberi affects the nervous system resulting in numbness of the hands and feet, confusion, trouble moving the legs, and pain.[1] A form with loss of appetite and constipation may also occur.[3] Another type, acute beriberi, is found mostly in babies and presents with loss of appetite, vomiting, lactic acidosis, changes in heart rate, and enlargement of the heart.[6]