• Oxidative Damage [ Time Frame: 2 weeks- Change from baseline following two week intervention with meat versus Quorn consumption ]
  Changes in the concentration of 8-Hydroxyguanosine levels in urine samples.
• Endogenous Short Chain Fatty Acid Production [ Time Frame: 2 weeks- Change from baseline following two week intervention with meat versus Quorn consumption ]
  Changes from baseline in the concentration of short chain fatty acids in stool samples, measures of propionate, acetate, butyrate valerate and isovalerate via Gas Chromatography.
• Gut Microbial Composition [ Time Frame: 2 weeks- Change from baseline following two week intervention with meat versus Quorn consumption ]
  Evaluation of post-intervention changes in the composition of the stool microbiota composition from baseline samples.
• Endogenous Production of Para-Cresol [ Time Frame: 2 weeks- Change from baseline following two week intervention with meat versus Quorn consumption ]
  Change in the concentration of the genotoxic metabolite para-cresol in urine samples
• Changes in MicroRNA Expression [ Time Frame: 2 weeks- Change from baseline following two week intervention with meat versus Quorn consumption ]
  Evaluation of change in the abundance of microRNAs in plasma separated from blood samples following the intervention.

• Blood Cholesterol [ Time Frame: 2 weeks ]
  Changes in levels of cholesterol in blood samples
• Blood Glucose [ Time Frame: 2 weeks ]
  Changes in levels of glucose in blood samples (HbA1c)

There is a strong association between a diet which is high in red and processed meat, while low in fibre, and the incidence of colorectal cancer. This study aims to evaluate the effects of replacing red and processed meat in the diet with an alternative meat product such as Quorn, on biomarkers of gut health that may be associated with colorectal cancer.

Quorn is a product which has a considerable fibre component; thus, the replacement of red and processed meat with Quorn, will not only reduce the amount of compounds implicated to have deleterious effects in the gastrointestinal tract (E.G. haem, nitroso compounds, heterocyclic amines), but will also increase the delivery of fibre into the gastrointestinal system, that may well have an overall positive impact on gut health.

In this study, the participants will consume 240 grams (raw weight) of either red and processed meat, or Quorn each day for a 2 week period, this will be followed by a 4 week period where they will return to their usual dietary habits; before swapping to consume the alternative food (red/processed meat or Quorn) for another 2 week period.

• Other: Red and Processed Meat
  Integration of 240 grams (raw weight) of red and processed meat into daily diet for 2 week period.
• Other: Quorn
  Integration of 240 grams (uncooked weight) of Quorn into daily diet for 2 week period.
  Other Name: Quorn Food

• Experimental: Red and Processed Meat
  240 grams (raw weight) of red and processed meat every day for 2 weeks
  Intervention: Other: Red and Processed Meat
• Experimental: Quorn
  240 grams (uncooked weight) of Quorn every day for 2 weeks
  Intervention: Other: Quorn

Inclusion Criteria:

• Male
• 18-50 years.
• Not been diagnosed with colorectal cancer, or adenomas.
• Habitual omnivorous dietary pattern.
• BMI ≥18-30 kg/m2.
• Blood HbA1c <58mmol/mol (<6.5%) (not diagnosed with diabetes)
• Fasting total cholesterol<7.8 mmol/l
• Triglycerides <2.3 mmol/l
• Normal liver function (assessed by measuring liver enzymes in the screening blood sample).
• Blood pressure lower than BP <140/90 mmHg.
• Not suffering any cardiovascular diseases/ heart diseases e.g. stroke in the past 12 months.
• Do not suffer from chronic gastrointestinal problems (e.g. Inflammatory Bowel Disease, Irritable Bowel Syndrome, coeliac disease)
• Do not take supplements or medication that effects gastrointestinal health
• Not participated in a pre-/probiotic or laxative trial within the previous 3 months.
• Not been prescribed and/or taken antibiotics in the previous 6 months.
• No history of alcohol misuse based on self-reported alcohol intake and measurement of liver enzymes in the screening blood sample.

Exclusion Criteria:

• Been diagnosed with colorectal cancer and/or colorectal adenomas.
• Been diagnosed with gastrointestinal disorders (e.g. Inflammatory bowel disease, irritable bowel syndrome, coeliac disease)
• Adherence to a dietary pattern which excludes foods from an animal origin.
• Abnormal blood biochemistry based on standard clinical cut- offs, as well as blood markers not fitting the inclusion criteria set.
• Have history of food intolerances/allergies (e.g. gluten or dairy) or intolerances (e.g. lactose).
• Taking, or unwilling to stop taking anti-oxidant supplements (e.g. vitamin C, vitamin E, Multivitamin tablets, polyphenol supplements)
• Received antibiotics in the previous 6 months.
• Have participated in similar dietary or prebiotic/probiotics study in the previous 3 months.
• Current smoker.