Inclusion Criteria:  men and women; aged 21 and 74 years; no history of chronic disease and in general good health; able to provide primary study outcome; and willing to tolerate study diets designed for controlled feeding.  Exclusion Criteria:  recent dietary changes, restrictions, allergies or preferences; health conditions that require management beyond the scope of the study (e.g. heart failure, kidney disease, liver disease, gastrointestinal disorder); history of drug or alcohol abuse; plans to leave the San Diego area before study completion; and lack of suitability per investigators' discretion.