This study evaluates how urine handling conditions can affect the concentrations of ~1,000 urine metabolites and attempts to quantify the degree of attenuation and/or potential bias in epidemiologic associations that may result from less than optimal sample handling conditions.

Metabolomics, the simultaneous quantification of concentrations of hundreds or thousands of metabolites simultaneously in a biological matrix, is a versatile analytical technique capable of accelerating biomarker-based discoveries in nutritional science. Recently, metabolomics has been applied to samples collected in feeding studies (1) and epidemiologic studies (2) to identify dozens of novel potential dietary biomarkers. Several large prospective cohort studies, many of which are collaborating in a metabolomics consortium led by the National Cancer Institute, have recently applied metabolomics to banked samples. This has made nutrition-related biomarkers suddenly available for tens of thousands of participants with follow-up for disease endpoints, enabling truly large-scale nutritional biomarkers and disease studies.

Inclusion Criteria:

• Age 20 to 65 years at beginning of study.
• BMI between 18.5 and 35.0 kg/m2.

Exclusion Criteria:

• Presence of cardiovascular disease, kidney disease, liver disease, gout, hyperthyroidism, untreated or unstable hypothyroidism, certain cancers, gastrointestinal disease, pancreatic disease, other metabolic diseases, or malabsorption syndromes.
• Unable or unwilling to give informed consent or communicate with study staff.
• Other medical, psychiatric, or behavioral factors that in the judgment of the Principal Investigator may interfere with study participation or the ability to follow the intervention protocol.

Men and women will be recruited from the area surrounding the BHNRC. There are several thousand government and privately employed workers located within a 10-mile radius of the BHNRC and several residential communities from which a cohort of volunteers will be recruited. The population includes an ethnically diverse group of subjects.