Interactions of Human Gut Microbiota With Intestinal Sweet Taste Receptors

Inclusion criteria

• Able to provide written informed consent
• Age 18-45 years
• Weight stable (± 3 kg) during the 6 months prior to enrollment
• BMI ≤ 25 kg/m2
• Consumption of less than a can of diet beverage or a spoonful of NCASs weekly (or each equivalent from foods) during the past month

Exclusion criteria

• Known coronary artery disease, angina or congestive heart failure
• Type 1 or Type 2 Diabetes (A1c ≥6.5%)
• Bleeding disorders
• Hemoglobin level < 12.5 g/dL for women; hemoglobin level < 13.0 g/dL for men
• Acute or chronic infections
• Hepatitis and/or cirrhosis
• Severe asthma or chronic obstructive pulmonary disease
• Renal insufficiency or nephritis (creatinine > 1.6 mg/dl)
• Prior bariatric surgery
• Inflammatory bowel disease or malabsorption
• Cancer within the last 3 years (except non-melanoma skin cancer or treated cervical carcinoma in situ)
• Psychiatric disorders or eating disorders
• Cushing's disease or syndrome
• Untreated or inadequately controlled hypo- or hyperthyroidism (abnormal TSH)
• Active rheumatoid arthritis or other inflammatory rheumatic disorder
• Pregnant or nursing women
• Smoking (smoking within the past 3 months)
• Less than 4 bowel movements per week
• Known hypersensitivity to saccharin, lactisole or any of its excipients.

Excluded medications include but are not limited to:

• Anti-diabetic agents
• Oral, injected or chronic topical steroids (inhaled steroids for mild asthma are acceptable)
• Antibiotic use (within the past 3 months)
• Other drugs known to affect immune or metabolic function
• Orlistat, phentermine, topiramate or other weight loss or anorectic agents (tricyclic antidepressants, atypical antipsychotics or other psychiatric drugs with effects on body weight)