If you drink a couple of cups of coffee each day, you're unlikely to suffer from adverse health effects from the caffeine. However, if you consume an excess amount of coffee, tea, cocoa or cola, especially if you have a poor diet, intestinal disorders, a chronic medical condition, drink excessive alcohol or are pregnant, the caffeine you consume could put you at risk for an iron deficiency.
Why Iron Absorption is Important
Your body needs to efficiently absorb iron to maintain many bodily functions, such as producing hemoglobin in your blood. Iron is also necessary for healthy cells, hair, skin and nails. Only a small fraction of iron from the food you eat is absorbed into your body by cells that line your intestine.
The iron is released into your bloodstream and stored in the liver, where it helps to make new blood cells and bone marrow. The recommended daily allowance for iron is 8 milligrams for men and 18 milligrams for women, according to the National Institutes of Health.
Caffeine and Iron Absorption
When you drink a cup of coffee, tea or some types of soda, the level of caffeine in your blood peaks in about one hour and maintains that level for several hours.
Half of the caffeine you consume remains in your body for up to six hours, and it may be 10 hours before the caffeine is gone from your bloodstream according to the Cleveland Clinic. During this time, several components in caffeine may inhibit the absorption of iron in your body, which could have long-term adverse effects on your health.
Iron Deficiency and Caffeine
Iron is needed for the production of red blood cells, which carry oxygen to all parts of your body. An iron deficiency that may lead to anemia could develop when your body's iron stores run too low. Iron deficiency marks an association between caffeine and anemia as a contributing factor to health problems.
The American Society of Hematology lists some of the symptoms of an iron deficiency, including pale or yellowish skin, fatigue, weakness, rapid heartbeat, craving for ice, smooth tongue, brittle nails and hair loss. See your doctor if you experience any of these symptoms.
Types of Iron Affected
The type of iron in the food you eat has a significant influence on how caffeine restricts its absorption. Iron in food comes in two forms — heme and nonheme iron. Nonheme iron is found mainly in plant-based foods, and only 2 to 20 percent of this type of iron is absorbed by the body. Both types of iron are found in meat, with about 55 to 60 percent being nonheme and the remainder being heme iron, according to the Iron Disorders Institute.
Caffeine can inhibit the absorption of nonheme iron, but has little effect on heme iron from animal tissue, says GP Notebook. So if you're a vegetarian or vegan who is dependent on plant-based foods for your iron, you should be especially attentive.
Tannin in Tea
Tea contains a chemical compound called tannin, which is a phenolic substance. Although tannin provides some antioxidant benefits, it also has the characteristic of inhibiting iron absorption, says the Journal of Nutritional Science. In some cases, tannins found in caffeine can have iron-inhibiting effects of up to 60 percent, according to the Iron Disorders Institute. It's recommended that you avoid consuming tea within two hours before or after eating an iron-rich meal.
Chlorogenic Acid in Coffee
Coffee contains chlorogenic acid, another phenolic substance found in caffeine. It's responsible for the bitter taste of coffee. Chlorogenic acid also has the ability to reduce the body's absorption of iron.
If You Need a Supplement
If you feel you have an iron deficiency, consult your doctor about needed supplements. The average dose for anemia is 100 to 200 milligrams of elemental iron, taken two or more times a day, advises the Cleveland Clinic. Take supplements on an empty stomach. Feosol.com says taking your iron supplement with food could inhibit its absorption by up to 50 percent.
Never take your supplement with coffee or other foods or beverages containing caffeine, calcium or antacids, which will also decrease the amount of absorption. Vitamin C assists with iron absorption from your supplement, so adding a little lemon juice to your tea may be helpful.
- NIH: Office of Dietary Supplements: Iron
- Journal of Nutritional Science: Coffee and Beverages Are the Major Contributors to Polyphenol Consumption From Food and Beverages in Japanese Middle-Aged Women
- Iron Disorders Institute: Diet
- American Society of Hematology: Iron-Deficiency Anemia
- Cleveland Clinic: Oral Iron Supplementation
- Feosol: Iron Absorption
- ScienceDirect: Coffee in Health and Disease Prevention: Chapter 21 - Chlorogenic Acids From Coffee
- CoffeeChemistry.com: Chlorogenic Acid
- GPNotebook: Coffee and Tea and Iron Absorption
- Iron Disorders Institute: Iron We Consume
- KidsHealth: Iron-Deficiency Anemia
- Cleveland Clinic: Caffeine: Tips for Breaking the Habit
- Journal of Research in Medical Sciences: Review on Iron and Its Importance for Human Health