These responses are indicative of an up-regulation of intestinal calcium absorption and renal reabsorption of calcium, respectively [2, 12]. However,

further studies specifically designed to assess calcium economy in the intestine and kidney are needed to confirm these findings. The differences in the response to calcium loading and results of our previous studies of pregnant and lactating women from The Gambia may indicate that the adaptations in calcium homeostasis may be different for Western and Gambian women. On theoretical grounds and as shown in our earlier studies in this population [19], it may be expected that with a calcium intake of ~350 mg/day, Ku 0059436 calcium absorption and renal calcium reabsorption are near their selleck inhibitor physiological maximum to meet the requirements for obligatory calcium losses in urine and faeces and, additionally during the reproductive cycle, for foetal skeletal mineralisation, secretion into breast milk (~200–300 mg/day) and post-lactational maternal bone mineral accretion [3]. This is underpinned by the low urinary calcium losses in Gambian NPNL and pregnant women shown in this study and other studies in this population [7], and by the absence of or only a moderate decrease in, urinary calcium losses during lactation as measured in 24 h, fasting and post-loading urine collections (this

study; [7]). An alternative explanation for the absence of differences in the calcemic response between reproductive OSBPL9 stages is the length of lactation (up to 2 years) and the typically short interval between cessation of lactation and next conception in this population [7]. The NPNL women in this study

may therefore be in a different physiological state than those women included in other reports [1, 2] and may have a greater or more prolonged rate of calcium incorporation into the maternal skeleton in response to cessation of lactation. The three groups were matched for age and parity, and the NPNL women were eumenhorreic. It is, therefore, unlikely that the findings of the study reflect biological differences in the ability to conceive. Despite the apparent moderate differences in calcium homeostasis between pregnant and lactating Gambian women compared to the differences seen in Western women, our earlier studies have shown that the changes in bone mineral status in lactating Gambian mothers at 13 weeks post-partum are similar to those reported for breastfeeding mothers with higher calcium intakes [5, 7]. This is consistent with other findings that dietary calcium intake is not a predictor of the changes in maternal bone mineral status associated with lactation [3, 4]. The conservation of bone mineral may be partly explained by the lower calcium outputs in breast milk, as mean milk calcium concentrations from Gambian women are lower than those of British women [7, 20, 21].