Proteomics is emerging as a valuable tool in nutritional research. Proteome analysis from plasma and blood cells can identify thousands of proteins that can potentially provide valuable new biomarkers for health, reveal early indications for disease disposition, assist in dietary responders from nonresponders, and enable the discovery of mechanisms of beneficial food component effects. This review discusses the latest developments in plasma, platelet and peripheral blood mononuclear cell proteomics, specifically in the field of nutritional proteomics, including issues relating to study design, sample preparation and data interpretation.