Calcium supplementation: effect on iron absorption

Article Abstract:

Calcium and iron are the nutrients most commonly deficient in adult women. Daily calcium supplements reduce the risk of osteoporosis (a disease of the bones that can cause fractures and disability), while iron supplements are especially important during pregnancy, lactation, and athletic training. Recent studies have suggested that iron absorption may be reduced by calcium supplements. To determine the effect of calcium supplements on iron absorption, calcium supplements were given to 28 women and 33 men; the subjects were young and healthy. Blood levels of iron were monitored and used as an indicator of iron absorption. The study group was subdivided into two groups, one with low iron reserves and one with normal iron reserves. In the group with low iron reserves, the addition of calcium carbonate (300 milligrams, or mg) to a meal containing a therapeutic dose of ferrous sulphate (37 mg of iron) resulted in a 44 percent decrease in iron absorption. However, in subjects with normal iron reserves, calcium carbonate did not decrease iron absorption when given with a meal or when taken with water. Calcium citrate had no significant effect on iron absorption when taken with food, but reduced iron absorption by 49 percent when taken without food. Calcium phosphate was the most potent inhibitor of iron absorption. Calcium phosphate reduced iron absorption by 57 percent when taken with food and by 62 percent when taken with water. It is concluded that calcium phosphate reduces iron absorption when taken with or without a meal, calcium citrate reduces iron absorption only when taken without food, and calcium carbonate does not significantly reduce iron absorption in persons with normal iron reserves. If both calcium and iron supplements are required, it is recommended that calcium carbonate be used and the supplements be taken between meals. If calcium supplements are taken with meals, they may interfere with the ability to meet the requirement for iron. (Consumer Summary produced by Reliance Medical Information, Inc.)

Care and treatment, Research, Complications and side effects, Dosage and administration, Dietary supplements, Nutrient interactions, Calcium carbonate, Iron deficiency diseases, Calcium phosphate, Calcium citrate

---

Adaptation in iron metabolism

Article Abstract:

The human body can remain healthy with a wide range of iron intakes and during physiologic stages that demand varying amounts of dietary iron. The body is flexible regarding iron supply and demand because intestinal iron absorption can adapt. The cells lining the intestines sense how much iron the individual needs, and adjust their uptake of dietary iron accordingly. It is not known how these cells receive signals concerning body iron stores, but it does appear that the signals are transmitted accurately. When iron needs are greatest, for example in pregnancy, or when the diet provides very little iron, the efficiency of absorption increases dramatically. In this way iron deficiency is resisted or at least delayed. Increased absorption cannot prevent anemia if intake is inadequate for requirements over the long term. Over a period of months or even years, a cumulative deficit can develop, depleting the body's iron reserves. When storage iron, which is found in the bone marrow, liver and spleen, is completely depleted, the functional form of iron found mainly in the red blood cells will show a deficit. Reduced hemoglobin concentration is an indicator that functional iron supplies are decreased. The intestinal absorption of iron adjusts to both iron deficiency and iron overload. While lack of iron is the more common nutritional problem, iron toxicity also occurs and can have serious consequences including scarring and failure of the heart and liver. When the body is overloaded with iron, intestinal absorption drops, but as with deficiency there is a limit to how much absorption can adapt to protect the body. (Consumer Summary produced by Reliance Medical Information, Inc.)

Analysis, Physiological aspects, Development and progression, Adaptation (Biology), Evolutionary adaptation, Intestinal absorption

---

Serum transferrin receptor for the detection of iron deficiency in pregnancy

Article Abstract:

During pregnancy the amount of iron required by the body increases, and iron deficiency anemia is common during pregnancy. It has been reported that even mild anemia can increase the risk of premature delivery and perinatal mortality. Diagnosing anemia during pregnancy can be difficult because during pregnancy the plasma volume (amount of fluid in the blood) increases. Transferrin is a protein that transports iron in the blood. It binds to a protein in cell membranes (called the transferrin receptor) and it transfers the iron into the cell. Recently, it was reported that during anemia, when iron supply is low, the amount of transferrin receptor in the blood increases. Therefore, a study was performed to determine if measuring the amount of transferrin receptor in the blood is a good method for diagnosing anemia during pregnancy. The study included 176 women in the third trimester of pregnancy. The amount of transferrin receptor in the blood was measured in each subject, and iron deficiency was diagnosed by measuring blood levels of hemoglobin (a red blood cell protein that contains iron), ferritin (the storage form of iron) and erythrocyte protoporphyrin (an iron-containing pigment in red blood cells). Forty-four percent of the women had depleted iron stores, and 13 were diagnosed as having iron deficiency anemia. Eighty-five percent of the women with iron deficiency anemia had abnormally high levels of transferrin receptor in their blood. It is concluded that blood transferrin receptor levels are a sensitive index of iron deficiency in pregnancy. (Consumer Summary produced by Reliance Medical Information, Inc.)

Evaluation, Diagnosis, Measurement, Pregnant women, Transferrin

Similar abstracts:

• Abstracts: The American Cancer Society National Prostate Cancer Detection Project: findings on the detection of early prostate cancer in 2425 men
• Abstracts: Depression, affect and negative symptoms in schizophrenia. The prognostic significance of negative symptoms in schizophrenia
• Abstracts: Comorbidity of mental disorders with alcohol and other drug abuse: results from the epidemiologic catchment area (ECA) study
• Abstracts: Examples abound of gaps in medical knowledge because of groups excluded from scientific study. Women's health initiative leads way as research begins to fill gender gaps

This website is not affiliated with document authors or copyright owners. This page is provided for informational purposes only. Unintentional errors are possible.