05 August 2009

“No Single Universal Calcium Requirement”

In 2000, with a bit of an incendiary tone, professor Christopher Nordin of Australia called for a rational position on calcium requirements based on individual variances and culture. The matter was one of controversy, lacking human studies because of their difficulty, but despite plenty of evidence that low calcium causes osteoporosis in animals.

Modern human studies in which researchers deprive subjects of calcium for long periods would be immoral, Nordin points out, although there have been at least a couple in the past. One in particular was performed 50 years ago on Norwegian prisoners that showed deprivation led to negative calcium balance, which would result in osteoporosis.

We also know that diet higher in animal protein and sodium increase urinary calcium; thus, the implication would be that populations of the developed world would need more calcium intake. And status of vitamin D influences calcium absorption; thus, living at a higher latitude, darker skin color, and less exposure to sunlight should never be ignored.

Of course, periods of hormonal changes deserves special attention. According to Nordin in a 2001 interview, “very little work” had been done to determine calcium requirements in postmenopausal state despite that the lacking estrogen effects on the bone are profound.

Still, nine years later and despite the data, many doctors and nutritionists in the U.S.A. and other countries are recommending calcium in general terms of simply meeting RDA. Or, those who understand that certain individuals need more or less calcium, may not be educating patients on facts relating to animal protein, sodium and vitamin D.

A complete, holistic view of each individual patient is necessary and national guidelines should be more forthright in making this assertion. As Nordin states, there is “no single universal calcium requirement” and we need to make sure that our patients know the facts.

No comments: