Effects of high compared with low calcium intake on calcium absorption and incorporation of iron by red blood cells in small children.
BACKGROUND
The potential benefits of increasing calcium intake in small children must be balanced with the potential risk to iron utilization from high calcium intakes.


OBJECTIVE
This study was designed to evaluate the relation between calcium intake and calcium absorption and iron incorporation into red blood cells.


METHODS
We performed a multitracer, crossover study of the absorption of calcium and red blood cell incorporation of iron in 11 preschool children aged 3-5 y who had been adapted for 5 wk to low- (502 +/- 99 mg) and high- (1180 +/- 117 mg) calcium diets. Stable-isotope studies were performed by using 44Ca and 58Fe given orally with meals and 46Ca given intravenously.


RESULTS
Iron incorporation into red blood cells 14 d postdosing was similar (6.9 +/- 4.2% compared with 7.9 +/- 5.5%; NS) with the low- and high-calcium diets, respectively. Total calcium absorption (181 +/- 50 compared with 277 +/- 91 mg/d; P = 0.002) was greater in children with the higher calcium intake.


CONCLUSIONS
Our findings indicate that small children may benefit from calcium intakes similar to those recommended for older children without adverse effects on dietary iron utilization.
US Department of Agriculture/Agricultural Research Service, Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine and Texas Children's Hospital, Houston, TX 77030-2600, USA.
S K
SK
Ames
B M
BM
Gorham
S A
SA
Abrams
D000042:Absorption; D002118:Calcium / Q000378:metabolism / Q000493:pharmacokinetics* / Q000652:urine; D002127:Calcium Isotopes; D002136:Calcium, Dietary / Q000008:administration & dosage*; D002675:Child, Preschool; D018592:Cross-Over Studies; D004912:Erythrocytes / Q000378:metabolism*; D005243:Feces / Q000737:chemistry; D005260:Female; D006801:Humans; D007501:Iron / Q000097:blood*; D007503:Iron Isotopes; D019266:Iron, Dietary / Q000008:administration & dosage; D008297:Male
D002127:Calcium Isotopes; D002136:Calcium, Dietary; D007503:Iron Isotopes; D019266:Iron, Dietary; D007501:Iron; D002118:Calcium