Negative calcium balance was observed during lactation in rural Mexican women who consumed a high-fiber diet. Furthermore, the data suggest that the hormones estradiol and PTHrP are involved in the regulation of calcium balance and of the calcium content of milk during lactation.

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Few experimental data regarding protein requirements of lactating women are available. This study was designed to determine the protein requirement of seven healthy lactating women from a poor Mexican community who were 2-6 mo postpartum and had a mean body mass index of 21.8 +/- 2 kg/m2. Nitrogen balances were performed at intakes of 0.8, 1.0, and 1.2 g.kg body wt-1.d-1 of a mixed protein diet (70% derived from vegetable sources). A balance at 1.2 g.kg body wt-1.d-1 of a high-quality mixed protein (80% from animal sources) was the reference. The experimental diets were designed to resemble the habitual diet in terms of energy and macronutrients. The balance responses to nitrogen intake were -35.5 +/- 12.6, -10.5 +/- 14.8, and 7.8 +/- 19.2 mg N.kg body wt-1.d-1, respectively. Equilibrium balance was attained at 178.9 +/- 25.8 mg N (1.1 g protein.kg body wt-1.d-1), close to current recommended dietary allowances, albeit the dietary protein was mostly from vegetable sources.

No abstract