Utilization of Calcium, Phosphorus, Magnesium, Iron, and Protein by Pregnant Women Consuming Self-Chosen Diets With or Without Vitamin, Mineral Supplements

The utilization of calcium, phosphorus, magnesium, iron, and nitrogen in 10 healthy pregnant women consuming self-selected diets was investigated. Seven-day balance experiments, conducted under ordinary home conditions, were spaced periodically throughout the duration of the pregnancy. A multiple vitamin-mineral supplement provided part of the calcium and iron intake of some subjects; others received their total mineral intake from food sources. Seven of the 10 subjects also completed a seven-day balance period within three to 11 weeks post partum.

The calcium intake of pregnant women with a balanced diet including dairy products was sufficient without supplementation of calcium. The magnesium intake of all 10 subjects was below that recommended for pregnant women, and balances were generally negative. An adaptation of the fecal loss of calcium and iron was suggested during the latter half of pregnancy, but the increased retention was not significant.

The retention of both calcium and phosphorus when calcium carbonate supplied 20% of the calcium intake was usually less than the retention of the minerals when calcium was provided entirely by food sources. The retention of iron whether partially provided by ferrous fumerate or ferrous sulfate or provided entirely by food sources appeared to be more dependent on the iron intake than the source of the mineral.

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