Animal models suggest that citrate-containing compounds augment absorption of aluminum from food and tap water, causing aluminum accumulation in bone and brain despite normal renal function. Citrate also enhances lead absorption in animals. We questioned whether use of calcium citrate by women as a calcium supplement causes an increase in aluminum or lead absorption from dietary sources. Changes in 24-hour urine aluminum and lead excretion, plasma aluminum level, and whole blood lead level were assessed in 30 healthy women before and during treatment with calcium citrate (800 mg of elemental calcium per day). During calcium citrate therapy, urinary aluminum excretion and plasma aluminum level increased significantly. In contrast, there were no changes in urine or whole blood lead levels. We conclude that treatment with calcium citrate significantly increases absorption of aluminum from dietary sources. Additional studies are needed to determine whether long-term use of calcium citrate leads to aluminum accumulation and toxicity.
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