Interactions of Human Gut Microbiota With Intestinal Sweet Taste Receptors

Inclusion Criteria:

1. Able to provide written informed consent

2. Age 18-45 years

3. Weight stable (± 3 kg) during the 6 months prior to enrollment

4. BMI ≤ 25 kg/m2

5. 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:

1. Known coronary artery disease, angina or congestive heart failure

2. Type 1 or Type 2 Diabetes (A1c ≥6.5%)

3. Bleeding disorders

4. Hemoglobin level < 12.5 g/dL for women; hemoglobin level < 13.0 g/dL for men

5. Acute or chronic infections

6. Hepatitis and/or cirrhosis

7. Severe asthma or chronic obstructive pulmonary disease

8. Renal insufficiency or nephritis (creatinine > 1.6 mg/dl)

9. Prior bariatric surgery

10. Inflammatory bowel disease or malabsorption

11. Cancer within the last 3 years (except non-melanoma skin cancer or treated cervical
carcinoma in situ)

12. Psychiatric disorders or eating disorders

13. Cushing's disease or syndrome

14. Untreated or inadequately controlled hypo- or hyperthyroidism (abnormal TSH)

15. Active rheumatoid arthritis or other inflammatory rheumatic disorder

16. Pregnant or nursing women

17. Smoking (smoking within the past 3 months)

18. Less than 4 bowel movements per week

19. Known hypersensitivity to saccharin, lactisole or any of its excipients.

Excluded medications include but are not limited to:

20. Anti-diabetic agents

21. Oral, injected or chronic topical steroids (inhaled steroids for mild asthma are
acceptable)

22. Antibiotic use (within the past 3 months)

23. Other drugs known to affect immune or metabolic function

24. Orlistat, phentermine, topiramate or other weight loss or anorectic agents (tricyclic
antidepressants, atypical antipsychotics or other psychiatric drugs with effects on
body weight)