High protein, calcium diet plus exercise protects bone health in pregnancy

A high protein and calcium diet in pregnant women, together with normal vitamin D status, lessens bone resorption and preserves bone formation, potentially resulting in bone health protection during pregnancy, suggests a study.

A team of investigators randomized 203 participants, who consented to the bone health substudy of the Be Health in Pregnancy trial, at 12‒17 weeks of gestation to receive either usual care (control) or a structured and monitored nutrition plus exercise plan (intervention), providing an individualized high dairy protein diet and a walking program through pregnancy.

The investigators used enzyme-linked immunosorbent assay to measure maternal serum total procollagen type 1 N-terminal propeptide (P1NP; bone formation), C-terminal telopeptide of type I collagen (CTX; bone resorption), and insulin-like growth factor-1 (IGF-1). They also measured vitamin D metabolites using ultra-performance liquid chromatography with tandem mass spectrometry at early and late pregnancy, 6 months postpartum, and in cord blood.

Of the participants, 187 completed all measures. Women in the intervention group had significantly higher intakes of total protein (p<0.0001), protein from dairy foods (p<0.0001), and calcium (p<0.0001) than those in the control group. On the other hand, the two treatment groups showed similar vitamin D intake in the second and third trimesters.

The intervention group also showed a significantly lower serum CTX at end of pregnancy (mean, 0.78 [n=91] vs 0.89 ng/mL [n=96]; p=0.034) and in cord serum (mean, 0.58 [n=31] vs 0.69 ng/mL [n=22]; p<0.025).

Serum concentrations of P1NP increased significantly (p<0.02) from early pregnancy to 6 months postpartum for women in the intervention group only, while serum 25-hydroxyvitamin D status was >50 nmol/L for 97 percent of all participants.

“Pregnancy induces bone mineral mobilization, which may be further compromised if diet and physical activity are suboptimal,” the investigators said.