Abstract: An exhaled breath condensate (EBC) collection device comprising two adjacent parts foldable together and apart from each other, a condensation zone to condense exhaled breath from a subject, the condensation zone being a third part provided between the two adjacent parts and connectable to cooling means arranged in each of the two parts being in cooling relationship with the condensation zone. There is also provided a method for detecting antigens or antibodies to the antigens, the method comprising collecting EBC from a subject using the EBC collection device, performing immunochromatographic testing (ICT) of the collected exhaled breath condensate, and interpreting the immunochromatographic testing results as follows: if the immunochromatographic testing results are positive, the antigens or antibodies to the antigens are detected, or if the immunochromatographic testing results are negative, the antigens or antibodies to the antigens are not detected.

Abstract: Provided are methods of using non-invasive assays to determine deuterium levels in a subject to effect health, disease, and athletic performance.