Submitted to: Complete Book
Publication Type: Book / Chapter
Publication Acceptance Date: December 19, 2003
Publication Date: December 19, 2003
Citation: Abrams S.A., Editor. 2003. Issues concerning calcium absorption and bone health. Cambridge, UK: The Royal Society of Chemistry Publishing. Interpretive Summary: None required.
Technical Abstract: The role of calcium absorption in bone health has been the subject of innumerable clinical research studies over the past several decades. Increasing absorbed calcium is viewed as a practical and oftentimes, marketable, approach to increasing the calcium available to the body for bone formation or prevention of bone loss. Calcium absorption is determined by numerous factors, however, not all of them readily controllable. Factors difficult to control include the effects of genetics (include gender and ethnicity as well as putative specific genetic polymorphisms), puberty and medical therapies (e.g. steroid use). More readily controllable are the chemical form and solubility of the calcium and other dietary factors, which can either enhance or decrease calcium absorption. It is important to begin by actually considering the meaning of the term 'calcium adsorption'. First, for nutritional purposes, calcium absorption is generally used interchangeably with the term 'calcium bioavailability'. This is because calcium absorbed from oral forms is essentially entirely available for 'utilization' by the body, especially the bones. In this chapter the two terms will be used interchangeable, as they are in most of the primary research sources. Another basic issue to consider is the difference between what is often referred to as 'net calcium absorption' and 'true calcium absorption'. The former term, derived from results from classical calcium balance studies, includes calcium that has been secreted into the intestine and then excreted in the stools (endogenous faecal excretion). Whereas this amount is positively correlated with calcium intake, it is negatively correlated with calcium absorption fraction. This is because as absorption fraction increases, more of the secreted calcium is reabsorbed before being excreted. The term 'true calcium absorption' refers to the primarily unidirectional flow of calcium from an ingested source and is determined by tracer techniques.