Vegetable Intake Effect on Heterocyclic Amine Metabolism

This is a randomized trial with crossover design, where each participant will undergo four study phases with a different test meal at the end of each phase. Every phase will consist of subjects consuming for six days their normal diet excluding cruciferous and apiaceous vegetables, alcohol, and caffeine. The participants will refrain from meat products for 24 hours prior to the test meal. On day seven of each phase and after an overnight fast, subjects will be randomly assigned to eat one of four meals: grilled hamburger with no vegetables grilled hamburger with steamed broccoli and Brussels sprouts grilled hamburger with steamed parsnips, fresh parsley, and celery sticks grilled hamburger with steamed broccoli, Brussels sprouts, and parsnips plus fresh parsley and celery sticks.

Colon cancer is the third most common cancer in the U.S. Convincing evidence suggests that high intake of red meat increases colon cancer risk, according to the 2007 AICR/WCRF Second Expert Report. The likely responsible mutagens are heterocyclic aromatic amines (HAA), which form naturally during the cooking of meat, poultry, and fish at high temperatures. Bioactivation of HAA to carcinogenic metabolites is primarily mediated by phase I biotransformation enzymes. Evidence suggests that the activity of many of these enzymes can be modulated by constituents in apiaceous vegetables (parsnips, celery, etc.) and cruciferous vegetables (broccoli, cabbage, etc.) In this trial researchers are comparing the effects of eating cruciferous vegetables, apiaceous vegetables, or both groups combined on HAA metabolism after eating grilled hamburger together in a single meal. They aim to define optimal dietary patterns and food combinations that maximize the safe excretion of dietary carcinogens through this trial. This contribution is significant because the knowledge gained will be applicable to the prevention of colon cancer as well as additional cancers.

In a randomized crossover design, each participant will undergo four study phases with a different test meal at the end of each phase. Every phase will consist of subjects consuming for six days their normal diet excluding cruciferous and apiaceous vegetables, alcohol, and caffeine. Furthermore, participants will refrain from meat products for 24 hours prior to the test meal, given that HAA are generally excreted in the urine by 12 hours post ingestion (18, 80). Compliance will be assessed with a questionnaire and the analysis of baseline levels of phytochemicals in spot urine samples that are to be collected prior to the test meal. On day seven of each phase and after an overnight fast, subjects will be randomly assigned to eat (in a private room near Dr. Truda's lab) one of four meals (prepared in a food grade lab also near Dr. Truda's lab)

Randomly assigned participants are given grilled hamburger with steamed broccoli and Brussels sprouts (3g/kg body weight combined)

Randomly assigned participants are given grilled hamburger (7 oz) with steamed parsnips, fresh parsley, and celery sticks (3g/kg body weight combined)

Randomly assigned participants are given grilled hamburger (7 oz) with steamed broccoli, Brussels sprouts, and parsnips plus fresh parsley and celery sticks (6g/kg body weight combined).

Test meal 2: grilled hamburger (7 oz) with steamed broccoli and Brussels sprouts (3g/kg body weight combined)

grilled hamburger (7 oz) with steamed parsnips, fresh parsley, and celery sticks (3g/kg body weight combined)

Test meal 3: grilled hamburger (7 oz) with steamed parsnips, fresh parsley, and celery sticks (3g/kg body weight combined)

grilled hamburger (7 oz) with steamed broccoli, Brussels sprouts, and parsnips plus fresh parsley and celery sticks (6g/kg body weight combined).

Test meal 4: grilled hamburger (7 oz) with steamed broccoli, Brussels sprouts, and parsnips plus fresh parsley and celery sticks (6g/kg body weight combined).

Inclusion Criteria: 18 years old or older Healthy Non-smoker Exclusion Criteria: No history of gastrointestinal, hepatic, or renal disorders Not currently taking any prescription or over-the-counter medications Not currently taking any herbal/vitamins supplements Not pregnant or lactating No allergies or intolerances to the foods that will be used in the study (parsnips, parsley, celery, broccoli, Brussels sprouts, and hamburger)