Study of the Reversibility of Glucose Intolerance Caused by Chronic Aspartame Consumption
Condition: Glucose Metabolism Disorder
MeSH terms: Metabolic Diseases; Glucose Metabolism Disorders; Glucose Intolerance
Study type: Interventional

Summary: 
      Experiments have shown that some artificial sweeteners like those in diet soda can cause
      changes in how the body responds to and uses sugar. These changes increase the chance of
      obesity, type 2 diabetes, and other metabolic diseases. In this study, the investigators plan
      to see if the most common artificial sweetener, aspartame (brand name Equal, NutraSweet),
      causes these changes. The investigators believe that if metabolic changes are observed in a
      person who consumes aspartame, then removing all aspartame from the diet might lead to a
      reversal of the changes and a normalization of test results.This would impact sweetener
      additives in our foods and thus decrease the incidence of obesity, diabetes, and the
      metabolic syndrome.
    

Detailed description: 
      Experiments have shown that some artificial sweeteners like those in diet soda can cause
      changes in how the body responds to and uses sugar. These changes increase the chance of
      obesity, type 2 diabetes mellitus, and other metabolic diseases. In this study, the
      investigators plan to see if the most commonly used artificial sweetener, aspartame, affects
      the body's response to sugar. The investigators believe that if metabolic changes are
      observed in a person who consumes aspartame, then removing all aspartame from the diet might
      lead to a reversal of the changes and a normalization of test results.

      The investigators plan to study two (2) cohorts of healthy volunteers: 1) Those who regularly
      drink at least three cans per day of diet soda that contains aspartame (Cohort 1, Aspartame
      Consumers) and 2) participants who consume less than or equal to two (2) cans of diet soda
      per week (Cohort 2, Aspartame Naïve Participants).

      Phase I of the study, the investigators will ask participants questions about their usual
      diet, including how much diet soda they usually drink. Participants will be screened by a
      test called the oral glucose tolerance test, or OGTT. This test involves coming to the
      hospital to drink sugary syrup, then have blood sugar checked every thirty (30) minutes for
      five (5) hours. Before the test, participants must refrain from eating or drinking anything
      for ten (10) hours. If the OGTT shows a high value, then the participant in cohort 1
      (Aspartame Consumers) who regularly drink 3 or more cans per day of diet soda will be
      approached about continuing into the second phase of the study. For the participants in
      cohort 2 (consume less than or equal to two (2) cans of diet soda per week; Aspartame Naïve
      Participants), this will be the end of their participation in the study.

      Phase II of the study, blood tests, OGTT, stool samples, and weight and body fat measurements
      a few times a week will track any changes in the participants during the study. During the
      phase II five (5) week study, participants will receive all of their meals from the
      Rockefeller University Hospital and should not have any outside food or drinks. The diet used
      throughout this study phase (II) is the Prudent Metabolic Diet. Participants can leave the
      hospital and continue to work, but must come for all tests and to receive meals. During Week
      One, participants will eat only food provided by the hospital but will continue to drink
      three (3) cans of diet soda per day. In Weeks Two through Four, participants will continue to
      eat food given to them by the hospital and will not be allowed to consume any foods or drinks
      that contain aspartame. In Week Five, participants will continue on the hospital diet, but
      will again start drinking three (3) cans of diet soda per day.
    

Intervention name(s): Oral glucose tolerance test (OGTT); Diet soda containing aspartame only
Intervention type(s): Other; Other
Intervention description(s): OGTT will be conducted following a ten (10) hour fast on Screening Visit 2 (Screening Visit 2 may be conducted between Day -42 to Day 1).; 7 days of 36 oz diet soda po daily (Week 1), followed by 21 days washout (Weeks 2-4), and 7 days rechallenge (Week 5); Prudent metabolic diet; Oral glucose tolerance test (OGTT) on days (+/-2) 3, 7, 10, 14, 21, 28, 31, 35
Allocation: Non-Randomized
Intervention model: Sequential Assignment
Masking: None (Open Label)
Primary purpose: Basic Science
Keywords: artificial sweeteners; obesity; diabetes; metabolic syndrome; aspartame