Table 3 Criteria for inclusion and exclusion

• Males and females aged 21–50 years

• BMI 20–30

• Willing to be randomized to take isolated xanthohumol as a dietary supplement (or placebo) for 8 weeks

• Willing to have blood drawn every 2 weeks and fast for 10–12 h before blood draws

• Willing and able to collect stool samples at home every 2 weeks

• Able to speak, read, and understand English

• Must be able to provide written informed consent

• Non-smokers (including tobacco and cannabis products, combusted or vaporized)

Permitted concomitant care or intervention during the trial:

• Use of over-the-counter medications as indicated on the label

• Multi-vitamin/multi-mineral products

• Dietary supplements except as detailed in exclusion criteria

• History of any chronic disease

• Consumption of more than 1 microbrew beer per day

• Typical intake of more than 2 alcohol-containing beverages per day, more than 14 per week, or more than 4 in any single day within 28 days prior to screening

• Use of NSAIDs more than once per week for headaches, routine aches/pains, etc.

• Use of any prescription drugs, including oral contraceptives (due to potential interference with mechanisms under investigation)

• Acute viral or bacterial infection, or recent infection within 14 days prior to screening or still requiring prescription medication for treatment

• Engaging in vigorous exercise more than 6 h per week

• Women who are lactating, pregnant, or planning pregnancy during the study period

• Within 3 months of screening:

 ° Use of prescription opioids for any reason

 ° Use of prescription corticosteroids for any reason

 ° Hospitalization (for any reason other than an elective medical procedure)

 ° Gastrointestinal surgery

• Current or within 30 days of screening:

 ° Intravenous nutrition support therapy

 ° Intake of anti-coagulant or anti-platelet prescription medications

 ° Intake of antibiotic, antiparasitic, or antifungal medications orally or intravenously

 ° Initiation of or changes to supplements or medications, an exercise regimen, or food plan

 ° Involvement in a significant diet or weight loss program, low-carb diet program, or very-low calorie liquid diet program

 ° Use of recreational drugs/substances

 ° Participation in another interventional research study

 ° Undergoing UV therapy

• Within 14 days of screening:

 ° Recent acute trauma occurring within 14 days prior to screening

 ° Recent (within 14 days prior to screening) intake of any dietary supplements containing xanthohumol flavonoids, or other natural products typically taken to modulate inflammation including curcumin, turmeric, fenugreek, hops, rosemary, ginger, white willow, devil’s claw, fish oil (doses > 1 g/day), bioflavonoids, or quercetin