Evaluation of magnesium, calcium and aluminum metabolism in rats and monkeys maintained on calcium-deficient diets.

The epidemiology of amyotrophic lateral sclerosis (ALS) in the Western Pacific indicates that low concentrations of calcium (Ca) and magnesium (Mg) and high levels of aluminum (Al) in soil and water in these foci are etiologically important. To determine the biochemical derangements and metal deposition induced by chronic dietary deficiencies of Ca, we maintained experimental animals on several regimens. Male Wistar rats, weighing 100g, were fed either a standard diet, low Ca diet, low Ca-Mg diet, or low Ca-Mg diet with high Al for 90 days. Ca, Mg and Al content was determined in central nervous system (CNS) tissues and bone using inductively coupled plasma emission spectrometry (ICP). In separate studies, five male Japanese macaques (Macaca fuscata), weighing 3.5 to 5 kg, were fed alternately with diets, normal in Ca, low in Ca, low in Mg, low in Ca-Mg, or low in Ca-Mg with added Al for four-week periods. Serum Ca, Mg, Al, parathyroid hormone (PTH), bone Gla-protein (BGP) and alkaline phosphatase (ALP) were measured after feeding each dietary regimen. Ca and Mg levels in lumbar vertebrae and femur were significantly reduced and bone Al levels were significantly increased in rats fed diets deficient in Ca alone or diets low in Ca-Mg with or without added Al. Al content in bones was also higher in rats fed the Ca deficient diets. In monkeys fed the low Ca-Mg diet with added Al, reduced levels of serum Ca and Mg, serum PTH, BGP, and ALP were apparent. Our data support the conjecture that deranged bone mineralization induced by chronic dietary deficiency of Ca accelerates mobilization of Ca and Mg from bone and deposition in brain.