Maintenance protein requirements: the need for conceptual re-evaluation.

Protein requirements have been traditionally discussed in terms of the needs for accretion, (growth, pregnancy etc.), and the needs to allow whole-body protein or nitrogen equilibrium, usually described as maintenance. In the case of slow-growing organisms like man it is apparent from an examination of any set of requirement estimates (e.g. Food and Agriculture Organization/World Health Organization/United Nations University, 1985) that net accretion is seldom a large component and that maintenance requirements represent the major component of protein needs for most of life. Maintenance requirements are often the primary focus for any discussion of protein requirements for the simple reason that they are the least understood. The purpose of the present paper is to review the current problems associated with both estimating the magnitude and understanding the nature of maintenance protein requirements in man.