The investigators will examine whether a non-invasive screening tool for CYP2C19 genetic variants can be developed by measuring limonene metabolism.

Cytochrome P450 2C19 is an important enzyme that metabolizes many drugs. However, individuals with genetic variants of CYP2C19, such as CYP2C19*2 and CYP2C19*3, are poor metabolizers of these drugs. Therefore, it is of interest to determine whether the investigators can develop a non-invasive assay to identify genetic variants of CYP2C19 by using a substrate for CYP2C19 found in citrus fruit, limonene. The purpose of the study is to examine changes in limonene levels in human breath after drinking orange peel extract for people with CYP2C19*2 and CYP2C19*3 genetic variants versus those that do not.

Inclusion Criteria:

• Age range: Greater than 18 years and less than 45 years.
• Gender: Male or Female
• Ethnicities: East Asian

Exclusion Criteria:

• Pregnant and/or Breastfeeding
• previous allergic reaction to limonene, citrus fruits, bovine gelatin, glycerin
• past medical history of cerebrovascular or cardiovascular disease
• veganism
• history of chest pain or shortness of breath in the past month
• certain medications that are CYP2C19 substrates or CYP2C19 inhibitors
• Non-East Asian descent
• age less than 18 y.o or age greater than 45 y.o

We are using quantitative assays for this study which reduce the need for masking of the participant or investigator.