This is a single-center prospective cohort study to evaluate the effect of short-term daily apple cider vinegar (ACV) supplementation on urine chemistry.

The primary objective of this study is to determine whether a two-week course of daily ACV supplementation significantly changes an individual's urine chemistry. The investigators will study this in healthy individuals and individuals with kidney stones.

Inclusion Criteria:

• Controls: Adults above the age of 18.
• Kidney stone patients: Adults above the age of 18.
• History of majority (>50%) calcium oxalate kidney stones

Exclusion Criteria:

• Anyone with a history of calcium phosphate stones (>50% calcium phosphate), uric acid stones, struvite stones, recent urinary tract instrumentation (<30 days), or recurrent urinary tract infections.
• Any individual who has had ACV outside of normal consumption in the prior month will be excluded.
• Any individual who has a history of a negative reaction (increased acid reflux, allergy) to ACV will also be excluded.
• Any individual with chronic kidney disease, underlying acid base disorder will also be excluded.