Conditional nutrition (I): concerning zinc as a beneficial but variable regulator of inflammation and experimental arthritis.

This article extends the concept of conditional pharmacology (Whitehouse and Vernon-Roberts 1991; Whitehouse 1995) that considers how both internal factors/disease and external/environmental factors may alter the availability or efficacy of exogenous drugs. The same and other conditioning factors may also affect the utility and value of many nutriceuticals that may be clearly beneficial in the context of inflammation but sometimes showing quite variable pharmaco-activity. This is illustrated by considering some factors affecting the bioavailability and pharmaco-efficacy of dietary ionic zinc, Zn (II) an essential trace metal and a critical regulator of inflammation and tissue repair. With chronic zinc deficiency (zincopenia) due to diet, drugs and/or disease, we can usually survive-but may not necessarily thrive. Some strategies to minimise zincopenia are considered, based upon finding efficient means for (1) preventing its cause and/or (2) using parenteral delivery of zinc supplements to circumvent dietary and enteric impediments to zinc bio-availability.