Effect of calcium supplements and stage of lactation on the calcium absorption efficiency of lactating women accustomed to low calcium intakes

Abstract

The effect of calcium intake on the calcium absorption efficiency from 100 mL cow milk was measured in lactating Gambian mothers habituated to a low-calcium diet [mean intake 7.08 mmol (283 mg)/d], and compared with UK lactating mothers consuming high-calcium diets [mean intake 29.2 mmol (1168 mg)/d] by using a double stable-isotope technique (oral 44Ca and intravenous 42Ca). In a double-blind trial starting 9 d postpartum, Gambian mothers were given a calcium supplement [17.85 mmol (714 mg)/d] or placebo for 12 mo. At 3 and 12 mo postpartum, mean (+/- SEM) calcium absorption from isotopically enriched milk was 52.3 +/- 3.1% (n = 25) and 47.2 +/- 4.8% (n = 24) in the unsupplemented Gambian mothers and 48.8 +/- 2.8% (n = 28) and 42.9 +/- 3.7% (n = 24) in the supplemented mothers, respectively. There was no effect of supplementation or stage of lactation on the efficiency of calcium absorption. At 3 mo postpartum the UK mothers absorbed 32.2 +/- 3.8% of the isotopically enriched calcium added to milk, which was significantly less than that of the Gambian mothers (P < 0.01).

Maternal Mineral and Bone Metabolism During Pregnancy, Lactation, and Post-Weaning Recovery

“…Low calcium intake does not reduce breast milk calcium, nor does it lead to increased resorption of the maternal skeleton during lactation (440, 535, 728 -731). Conversely, high calcium intake similarly fails to increase breast milk calcium or reduce skeletal resorption during lactation (206,275,440,452,484,535,723,729,730); its only effect may be to increase urinary calcium excretion. These data from randomized clinical trials and cohort studies indicate that it does not matter how much calcium is consumed during lactation because maternal skeletal resorption is hormonally programmed to supply needed calcium.…”

Trace Element and Mineral Nutrition During Lactation

“…A study of Gambian women, who traditionally consume a low-calcium diet, showed that calcium absorption was increased, apparently as an adaptation to low calcium intake. During lactation, the additional need for calcium seemed to be met by decreased calcium excretion rather than by a further increase in absorption (10). Lactating women do experience a transient bone loss and calcium supplementation has little impact on lactation induced changes in calcium homeostasis (11).…”

Calcium requirement is a sliding scale

“…Vitamin D may be another factor contributing to low fracture rates in developing countries at low latitudes (34). In fact, high calcium absorption (resulting from a high serum 1,25-dihydroxyvitamin D concentration) and low urinary calcium were reported in Gambian women (42)(43)(44) and these 2 factors in combination would greatly reduce the calcium requirement.…”