Poor diet or inadequate absorption of dietary iron can cause iron deficiency anemia, a condition characterized by low hemoglobin levels and symptoms of fatigue and weakness. Green tea consumption can interfere with the absorption of iron from foods and supplements.
Iron Absorption
The body absorbs only a small percentage of dietary iron. Healthy adults absorb 15 to 35 percent of heme iron from animal-based foods, and only two to 20 percent of nonheme iron from plant-based foods, fortified foods and dietary supplements. Tannins found in green tea can hinder absorption of nonheme iron. Drink green tea between meals, at least two hours before or after consuming nonheme iron, to avoid hindering absorption. Herbal teas do not contain tannins and do not affect iron absorption.
Other Absorption Factors
Other substances that can decrease iron absorption include calcium, polyphenols, proteins found in soybeans and phytates found in whole grains and legumes. Meat proteins and heme iron sources can improve iron absorption, as can foods rich in vitamin C, such as citrus fruits.
Iron Deficiency
Iron deficiency affects as much as 80 percent of the world's population, notes the National Institutes of Health Office of Dietary Supplements. Insufficient intake or absorption of iron can cause iron deficiency and iron deficiency anemia. Without iron, the body cannot produce hemoglobin, a protein in red blood cells that carries oxygen to organs and tissues. Signs of iron deficiency anemia include fatigue, weakness, difficulty maintaining body temperature and an inflamed tongue. Iron deficiency anemia may cause decreased immune function and decreased performance at school or work, according to the National Institutes of Health Office of Dietary Supplements.
High-Risk Groups
Some people have a higher risk of developing iron deficiency anemia, and may need iron supplements to prevent a deficiency. Teenage girls and women of childbearing age lose iron during menstruation, so they need more iron than men and postmenopausal women. Pregnant women, preterm and low birth weight infants, toddlers and people with renal failure and gastrointestinal disorders all need extra iron, according to the National Institutes of Health Office of Dietary Supplements. These people should be especially careful not to drink tea with dietary sources of iron.
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