The primary objective of this study is to determine how daily consumption of kale changes the activity of human xenobiotic metabolizing enzymes. Secondary objectives are to measure absorption and metabolism of kale phytonutrients, and to determine how kale consumption affects gene expression related to metabolism and lipid measures associated with cardiovascular health.

Consumption of Brassica vegetables (which include broccoli, cabbage, and kale) is inversely associated with the incidence of several cancers, including cancers of the lung, stomach, liver, colon, rectum, breast, endometrium, and ovaries. Brassica vegetables are a good source of many nutrients, but the unique characteristic of Brassicas is their rich content of glucosinolates. Glucosinolates are sulfur-containing compounds that are converted to bioactive metabolites by a plant enzyme called myrosinase, which is released when the vesicles containing myrosinase are ruptured by chewing or cutting. These bioactive compounds are considered to be the active agent for cancer prevention. Their ability to reduce risk of cancer may derive in part from their ability to modulate foreign-substance metabolizing enzymes, which include enzymes called Phase I cytochrome P450s and Phase II enzymes.

The primary aim of this study is to investigate how daily consumption of kale influences foreign-substance metabolizing enzymes, which in turn may reduce cancer risk. Secondary aims of this study include measuring metabolism of kale nutrients, effect of kale consumption on fecal microbiota, and how kale consumption influences risk factors for cardiovascular disease.

Inclusion Criteria:

• 5 years cancer free
• Not a tobacco product user
• Blood glucose less than 126 mg/dL
• Able to voluntarily agree to participate and sign an informed consent document

Exclusion Criteria:

• Brassica vegetable allergy or intolerance
• use of oral contraceptives
• Women who have given birth in the previous 12 months
• Type 2 diabetes requiring the use of diabetes pills, insulin, or non-insulin shots
• Use of blood-thinning medications such as Coumadin (warfarin), Dicumarol, or Miradon (anisindione)
• History of bariatric surgery or nutrient malabsorption disease
• Pregnant, lactating, or intending to become pregnant during the study period
• Crohn's disease or diverticulitis
• Suspected or known strictures, fistulas or physiological/mechanical GI obstruction
• Self-report of alcohol or substance abuse within the past 12 months and/or current acute treatment or rehabilitation program for these problems (long-term participation in Alcoholics Anonymous is not an exclusion)