The purpose of this study is to assess the impact of consuming unprocessed and processed red meat on gut microbiota in young healthy adults in a cross-over, randomized controlled feeding trial.

The purpose of this study is to assess the impact of consuming processed and unprocessed red meat on gut microbiota in young healthy adults in a cross-over, randomized controlled feeding trial. The hypothesis is that compared to consuming a meat-free lacto-ovo vegetarian (LOV) diet, (1) consuming the LOV diet with unprocessed red meat or processed red meat (omnivorous diet) will shift the gut microbiota with greater abundance of the bacteria Lactobacillus and other SCFA producers such as Clostridium XIVa, and no increase of pathogenic bacteria. The concentration of SCFA in stools will also increase in subjects consuming the unprocessed red meat diet. Compared to consuming a meat-free lacto-ovo vegetarian (LOV) diet, (2) consuming the LOV diet with processed beef and pork (omnivorous diet) will result in a comparable shift in gut microbiota as unprocessed red meat, except for greater abundance of taxa Erysipelotrichaceae and lower abundance of Lachnospiraceae.

Inclusion Criteria:

• male or female,
• 20-35 years old,
• BMI 20.0-29.9 kg/m2,
• fasting serum total cholesterol <240 mg/dL, low-density lipoprotein cholesterol <160 mg/dL, triglycerides <400 mg/dL, and glucose <110 mg/dL;
• systolic/diastolic blood pressure <140/90 mmHg;
• body weight stable for 3 months prior (±3 kg); stable physical activity regimen 3 months prior;
• medication use stable for 6 months prior and not using medications or supplements known to impact gut function;
• on-smoking; not drinking more than 2 alcoholic drinks per day;
• non-diabetic,
• no history of gastrointestinal disorders, surgeries or cancers;
• non-pregnant and not lactating.
• Participants must be willing and able to consume the prescribed diets (lacto-ovo vegetarian and omnivorous).

Exclusion Criteria:

• male or female < 20->35 years old,
• BMI <20.0- >29.9 kg/m2,
• fasting serum total cholesterol >240 mg/dL, low-density lipoprotein cholesterol >160 mg/dL, triglycerides >400 mg/dL, and glucose >110 mg/dL;
• systolic/diastolic blood pressure >140/90 mmHg;
• body weight stable for <3 months prior (±3 kg);
• stable physical activity regimen < 3 months prior;
• medication use unstable for 6 months prior and using medications or supplements known to impact gut function;
• smoking;
• drinking more than 2 alcoholic drinks per day;
• diabetic,
• history of gastrointestinal disorders, GI surgeries or GI cancers;
• pregnant or lactating.