Vitamin D status does not influence the breast‐milk calcium concentration of lactating mothers accustomed to a low calcium intake

Abstract

Plasma 25-hydroxy-vitamin D and breast-milk calcium concentration were measured at 3 months of lactation in 60 Gambian mothers accustomed to a low calcium diet, of whom 30 were consuming a calcium supplement and 30 were receiving a placebo, and in 48 British mothers. The plasma 25-hydroxy-vitamin D concentration of the Gambian women was not affected by either calcium supplementation (supplemented, 64.4 +/- 2.5 nmol l(-1); placebo, 64.9 +/- 3.5 nmol l(-1); mean +/- SE) or season. The British average was lower (53.9 +/- 3.0 nmol l(-1), p = 0.004), owing to marked seasonal effects. The breast-milk calcium concentration was lower in The Gambia (supplemented, 5.38 +/- 0.13 mmol l(-1); placebo, 5.10 +/- 0.13 mmol l(-1); British, 6.93 +/- 0.15 mmol l(-1), p < 0.0001). There was no relationship between plasma 25-hydroxy-vitamin D and breast-milk calcium concentration in any group. There was no trend towards lower breast-milk calcium concentration in women with vitamin D status towards the bottom of the normal range or in British women during the winter. This study provides no support for the hypothesis that breast-milk calcium concentration is influenced by vitamin D status or that lactating women with a low calcium intake are at particular risk of vitamin D deficiency.

Calcium economy in human pregnancy and lactation

“…However, no association between breast-milk Ca concentration and maternal vitamin D status (25OHD) was observed in a study of British and Gambian women (242) , and no differences in breast-milk Ca were observed between US mothers who consumed 50 (238) .…”

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

“…Observational cohort studies (145,731,862,893) and randomized interventional trials (13,14,60,402,453,672,780,788,789,965) have not shown any effect of higher 25OHD concentrations or vitamin D supplementation to alter maternal mineral or skeletal homeostasis in otherwise healthy, lactating women across a broad range of vitamin D intakes and 25OHD levels. Vitamin D supplementation raises maternal 25OHD levels with a similar dose-response effect as in nonpregnant or nonlactating women.…”

“…A randomized trial found no effect of calcium supplementation on milk PTHrP content, but there may be a diurnal variation with more PTHrP in milk obtained in the morning compared with the afternoon (208). Diets that are high (206,452,484,723) or low (728 -731) in calcium, or high (60) or low (731) in vitamin D, do not affect milk calcium content.…”

“…Breast milk calcium content is unaffected by maternal 25OHD over a wide range from 25 nM (10 ng/ml) to 160 nM (64 ng/ml) (60,731). This includes cohort studies that have examined low maternal vitamin D intakes and 25OHD concentrations (731), and randomized interventions which found that maternal intake of 2,000 -6,400 IU vitamin D/day failed to change the calcium content of milk compared with an intake of 400 IU/day (60,402,965), even though the 6,400 IU dose raised maternal 25OHD to 160 nM (64 ng/ml) (965).…”

“…This includes cohort studies that have examined low maternal vitamin D intakes and 25OHD concentrations (731), and randomized interventions which found that maternal intake of 2,000 -6,400 IU vitamin D/day failed to change the calcium content of milk compared with an intake of 400 IU/day (60,402,965), even though the 6,400 IU dose raised maternal 25OHD to 160 nM (64 ng/ml) (965). On the other hand, several individual cases from India revealed that milk calcium content was lower in mothers presenting with overt vitamin D deficiency with mean 25OHD values of 6 nM (2.5 ng/ml), hypocalcemia, hypophosphatemia, and markedly elevated PTH (903).…”