The purpose of this study is to learn more about what happens in the human body after consuming a meal that contains ultra-processed foods like hamburgers, and if this is different to what happens after consuming a meal that contains lots of whole foods, like fresh vegetables, instead.

The purpose of this study is to discover more about how the human body and the bacteria living in our intestines, known as "gut flora," react to different foods a person may consume. The investigators want to know if there are differences in compounds measured in a participant's blood and urine after eating different foods. Specifically, the investigators are interested in seeing if there are differences in these compounds after eating ultra-processed foods, like hamburgers and french fries, versus eating whole foods, like fresh fruits and vegetables. The investigators also want to know if the bacteria in our intestines may change the levels of these compounds. To this end, some subjects will be asked to take antibiotics to suppress the gut flora for three days before eating the challenge meal. Suppression of gut flora is a known effect of the antibiotics used in this study. Participants will have two study visits.

Inclusion Criteria:

• Men and women age 18 years or above.
• Able to provide informed consent and comply with study protocol
• Able to remain on a stable aspirin regimen (either on or off aspirin or aspirin products) for 1 week prior to starting study until the end of the study period.

Exclusion Criteria:

• Significant chronic illness or end-organ dysfunction, including known history of uncompensated heart failure, renal failure, pulmonary disease, hematologic diseases.
• Active infection or received antibiotics within 6 months of study enrollment.
• Use of over-the-counter probiotic within past month.
• Chronic gastrointestinal disorders.
• Intolerance to probiotic therapy.
• Allergy to vancomycin, ciprofloxacin, neomycin, metronidazole, or lactose.
• Allergy to any of the food components of the challenge meals.
• Having undergone bariatric procedures or surgeries such as gastric banding or bypass.
• Pregnancy.