Protein requirements of marginally nourished lactating women

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 [+ or -] 2 kg/[m.sup.2]. Nitrogen balances were performed at intakes of 0.8, 1.0, and 1.2 g [center dot] kg body w[t.sup.-1] [center dot] [d.sup.-1] of a mixed protein diet (70% derived from vegetable sources). A balance at 1.2 g [center dot] kg body w[t.sup.-1] [center dot] [d.sup.-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 [+ or -] 12.6, - 10.5 [+ or -] 14.8, and 7.8 [+ or -] 19.2 mg N [center dot] kg body w[t.sup.-1] [center dot] [d.sup.-1], respectively. Equilibrium balance was attained at 178.9 [+ or -] 25.8 mg N (1.1 g protein [center dot] kg body w[t.sup.-1] [center dot] [d.sup.-1]), close to current recommended dietary allowances, albeit the dietary protein was mostly from vegetable sources.