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###### Department of Health and Human Services

###### National Institutes of Health

Notice is hereby given of the National Institutes of Health (NIH) Office of Dietary Supplements (ODS) Nutrient Biomarkers Analytical Methodology: Vitamin D Workshop to be held Wednesday, December 16, 2009 at the Bethesda North Marriott Hotel & Conference Center in Bethesda, Maryland 20852.

*Summary:*                    Vitamin D is a fat-soluble vitamin that is naturally present in very few foods, added to others, and available as a dietary supplement. It is also produced endogenously when ultraviolet rays from sunlight strike the                           ( print page 51870)                        skin and trigger vitamin D synthesis. Vitamin D obtained from sun exposure, food, and supplements is biologically inert and must undergo two hydroxylations in the body for activation. The first occurs in the liver and converts vitamin D to 25-hydroxyvitamin D [25(OH)D], also known as calcidiol. The second occurs primarily in the kidney and forms the physiologically active 1,25-dihydroxyvitamin D [1,25(OH)2                    D], also known as calcitriol.                

                    Serum concentration of 25(OH)D is the best indicator of exposure to vitamin D from all sources. It reflects vitamin D produced cutaneously and that obtained from food and supplements. There is considerable discussion of the serum concentrations of 25(OH)D associated with deficiency (                    *e.g.,*                     rickets), adequacy for bone health, and optimal overall health. In fact, different assay methods are used to assess 25(OH)D. The methods themselves vary and there are considerable differences among laboratory results even when they use the same method.                

Given the uncertainties in vitamin D measurement, the NIH/ODS will host this one-day workshop to evaluate the state of analytical methods. The intent of the Nutrient Biomarkers Analytical Methodology: Vitamin D Workshop is to develop strategies for resolving inconsistencies between results obtained following quantitative determination of selected nutrients in biological materials such as serum when different measurement techniques are used. The desired outcomes of this meeting are to identify strengths and weaknesses of analytical approaches available for the quantification of the nutritional biomarker of Vitamin D status, circulating 25(OH)D in biological samples and to discuss analytical methods, including criteria for selection of method(s); role of reference methods and samples; sample preparation and interpretation of results.

The workshop will consist of a series of short, focused podium presentations interspersed with open discussion sessions on the currently available analytical methods and interpretation of findings. A final session will summarize the discussions, identify knowledge gaps, and suggest a research agenda for future studies.

The sponsor of this meeting is the NIH Office of Dietary Supplements.

## Registration

                    Space is limited and will be filled on a first-come first-served basis. There is no registration fee to attend the workshop. To register please forward your name and complete mailing address including phone number via e-mail to Ms. Tricia Wallich at                     *twallich@csionweb.com*. Ms. Wallich will be coordinating the registration for this meeting. If you wish to make an oral presentation during the meeting, you must indicate this when you register and submit the following information: (1) A brief written statement of the general nature of the comments that you wish to present, (2) the name and address of the person(s) who will give the presentation, and (3) the approximate length of time that you are requesting for your presentation. Depending on the number of people who register to make presentations, we may have to limit the time allotted for each presentation. If you don't have access to e-mail please call Ms. Wallich at 301-670-0270.                

Dated: October 2, 2009.

Paul M. Coates,

Director, Office of Dietary Supplements, National Institutes of Health.

[FR Doc. E9-24334 Filed 10-7-09; 8:45 am]

BILLING CODE 4140-01-P