Nitrogen balance describes the relationship between the nitrogen taken in and the nitrogen excreted by the body and serves in nutrition science as a measure of protein metabolism, since protein, unlike carbohydrates and fat, contains nitrogen. A balanced result means that intake and excretion roughly match.
A positive nitrogen balance is when more nitrogen is taken in than excreted, which can indicate a build-up of body protein, for example during growth or muscle building. A negative balance, on the other hand, points to a breakdown of body protein, as can occur with inadequate protein intake or in some illnesses.
Relevance for nutrition and sport
In strength sports, nitrogen balance is occasionally used to roughly assess the effect of a particular protein intake on muscle building, even though it is hardly ever measured directly in everyday life. For most people it is more a theoretical concept than a value they determine themselves.
More important than nitrogen balance in detail is, in practice, an adequate protein intake spread over the day that matches individual needs. The guide protein requirements explains how to estimate this need. A sufficiently high intake spread over several meals is regarded as a practical approach.
