Five of these six women remained in negative balance at week 9. In addition, the data of Castaneda et al demonstrate that N equilibrium shown in longer-term balance studies may be established as a result of significant detrimental changes in body composition. Thus, N balance data generated from longer-term studies do not provide an accurate assessment for protein requirements of subjects in the metabolic state in which they entered the study. The data, with one flawed exception, indicate that the safe level of protein intake for older adults may be higher than currently recommended. Additional direct comparisons between younger and older adults are desirable as a basis for any revised recommendations.
More research is needed to determine whether gender-related differences occur.
Nitrogen balance studies in apparently healthy elderly people and those who are housebound. J. Nutr . Elderly women accommodate to a low-protein diet with losses of body cell mass, muscle function, and immune response. Technical Report Series 724. World Health Organization.