The Canadian and US government-sponsored review is seeking to find out if daily recommended intakes (DRIs) established in 1997 require updating, and now CRN has put its knowledge and opinion on the table with the IOM’s Food and Nutrition Board (FNB).
Vitamin D
In regard to vitamin D the Washington DC-based dietary supplements trade group’s vice predident of regulatory and scientific affairs, Andrew Shao, PhD, was forthright in stating:
“It is now widely recognized in both the US and Canada, that the last iteration of
recommendations for vitamin D published back in 1997, the first in a series of publications on nutrient DRIs, are woefully outdated.”
That recommendation of between 200 and 600 IU per day, was based on a level required to avoid diseases such as rickets or osteomalacia, “diseases of overt vitamin D deficiency”.
A “plethora of new data” pointed to the level being revised, Dr Shao said.
“New recommendations must go beyond avoidance of diseases of overt deficiency affecting only bone related outcomes, and must address avoidance of long-term inadequacy or insufficiency, a consequence of which may be increased risk for several
chronic diseases.”
A level of 1000 IU or more was suggested. A tolerable upper intake limit – the level above which safety cannot be guaranteed and currently 2000mg – of 10,000 or more was suggested, in reference to a recent study.
Calcium
For calcium, and all other nutrients, it questioned the value of randomized controlled studies (RCTs), the scientific “gold standard” that authorities tended to privilege in many jurisdictions and to look to new potential health areas.
“We urge the FNB committee to consider in its process other relevant endpoints, in addition to bone health, such as colon cancer risk,” CRN said.
The “gold standard” preference needed a rethink because “it fails to account for the fact that many RCTs to date have been designed as if they were assessing the effects of drug therapies”.
It added: “While all would agree that RCTs are needed to firmly establish causality between, for example, intake of a given nutrient and a relevant health-related outcome, in actually, most RCTs are not adequately designed to properly assess such relationships.”
Other scientific models might include:
- measurement of global indices of health
- a more holistic approach that combines assessment of multiple nutrients together with other behavioral modifications
- measurement of single nucleotide polymorphisms (SNPS)
- baseline and ongoing assessments of nutrient status
“We urge the IOM and FNB committee to consider these comments, not only for vitamin
D and calcium, but as they apply to the DRI process for all nutrients,” Sjao concluded.
The US and Canadian governments are sponsoring a review of vitamin D and calcium that may lead to the establishment of higher.
IOM’s report is due in the spring of 2010.