The specific aim of this protocol is to examine differential expression of specific mRNAs and proteins that occur when the dietary intake of zinc is acutely reduced below the dietary requirement for a period of ten days.

Methods to assess the dietary zinc status of individual humans or populations are lacking. The study is a three period observational study of biomarkers of zinc status before, during and after zinc depletion. The entire dietary study will take 24 days composed of three parts:

• Dietary Acclimation (Phase 1): 7 days
• Dietary Zinc Restriction (Phase 2): 10 days
• Dietary Zinc Repletion (Phase 3): 7 days

The dietary treatments and all blood draws will be carried out in the General Clinical Research Center (GCRC) at University of Florida. Previous research from has shown that both metallothionein gene expression and specific zinc transporter genes in blood leukocyte subsets are directly proportional to dietary zinc intake. By using cDNA array analysis and quantitative PCR technology with blood RNA, those genes most sensitive to zinc nutrition will be identified for the purpose of developing zinc status assessment methods on how zinc functions in human biology.

Additionally, buccal mucosal cells will be collected in the GCRC by using swabs, i.e., in a noninvasive manner, to further characterize the expression pattern of the genes under study. This method has the potential for nutrition studies in the field (international nutrition, etc).

Inclusion Criteria:

• Healthy male
• 21-35 years
• Body weight above 110 lb

Exclusion Criteria:

• Use of dietary supplements
• Smoker
• Alcoholic
• Under medication
• History of chronic disease
• Use of denture cream
• Vegetarian
• Food allergy

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