A condition characterized by subnormal levels of HEMOGLOBIN, the oxygen-binding PROTEIN in blood. Half a million Americans are at risk for anemia, including 40 percent of pregnant women, pre-menopausal women, vegans (those who eat no animal products), adolescents relying on JUNK FOOD diets, infants, and children with inadequate diets.
Anemia may result from either an inadequate number of RED BLOOD CELLS (erythrocytes) or an abnormally low hemoglobin content of red blood cells. With deficient functional red blood cells, the oxygen supply to tissues is inadequate for optimal RESPIRATION, causing shortness of breath, FATIGUE, weakness, pallor, headache, and lowered resistance to infection. There are two general types of anemia based on red blood cell size. Megaloblastic anemia is characterized by large red blood cells; their shortened life span results in a decreased number of cells. Microcytic anemia is characterized by small red blood cells with reduced hemoglobin content. Many nutritional deficiencies lead to anemia. Inadequate dietary IRON, COPPER, FOLIC ACID, PROTEIN,
VITAMIN B6, vitamin B12, VITAMIN C, VITAMIN A, VITAMIN E, and RIBOFLAVIN can cause this condition. Each of these nutrients is required for the production of red blood cells (ERYTHROPOIESIS). Iron deficiency anemia is the most common diet-related anemia in the United States and it represents the last stage of iron deficiency. It is characterized by small, pale red blood cells (microcytic anemia), due to chronic blood loss or inadequate iron intake. Symptoms include FATIGUE, pallor, and shortness of breath. Studies of the nutritional status of developed nations have routinely found up to 30 percent of a population with iron deficiency. Groups that are at highest risk are children under the age of two years, teenage women, pregnant women, and the elderly. Pregnancy drastically increases the requirement of iron. In terms of blood loss the most common causes of iron deficiency are excessive bleeding during menstruation and intestinal bleeding due to parasites, ulcers, or malignancy. Iron deficiency can be caused by impaired iron uptake by the intestine, due to a lack of stomach acid (ACHLORHYDRIA) or from chronic DIARRHEA. With iron deficiency, the resulting anemia can be treated by iron supplementation.
Deficiencies of either folacin or vitamin B12 can cause anemia because each is essential for DNA synthesis and deficiencies impair erythrocyte production. Folic acid deficiency is much more common because folic acid stores in the body are small, yet folic acid participates in many biosynthetic reactions. On the other hand, vitamin B12 is stored in the LIVER, and only trace amounts are required daily for a few specific functions. Anemia due to inadequate folic acid and vitamin B12 produces large (macrocytic) cells with a short life span. This form of anemia can occur when intake of fresh vegetables is very limited, or when the need for folic acid outstrips intake, as may occur during pregnancy or in ALCOHOLISM. Treatment with folic acid can ameliorate megaloblastic anemia, yet mask an underlying vitamin B12 deficiency. This point emphasizes that treatment of anemia requires expert medical supervision.
Anemia can also indicate a serious condition unrelated to diet. Non-nutritional causes of anemia include chronic blood loss and congenital defects in red blood cell formation, such as thalassemia or sickle cell anemia, due to mutant hemoglobins, and spherocytosis (spherical red blood cells). Hemolytic anemia is the result of excessive hemolysis (destruction of red blood cells) in susceptible people exposed to bacterial toxins, toxic chemicals, or drugs that may produce JAUNDICE.
Anemia also may result from reduced nutrient uptake due to the presence of parasites and chronic infections, gastrointestinal disease or bowel resection
A form of ANEMIA caused either by a dietary deficiency of VITAMIN B12 or by inadequate B12 absorption. It is characterized by quite large red blood cells (macrocytic) that are overloaded in the hemoglobin (hyperchromic). Low vitamin B12 consumption is a concern for strict VEGETARIANS who avoid meat and meat products. Pernicious anemia is also caused by inadequate vitamin B12 uptake. Normally, the gastric lining secretes a PROTEIN called INTRINSIC FACTOR that’s needed to specifically bind vitamin B12. Because this protein is required for vitamin B12 absorption by the intestine, inadequate intrinsic factor production, even with adequate dietary B12, can cause pernicious anemia.
