Metabolic Effects of Non-Nutritive Sweeteners

Background:

• Artificial sweeteners, such as sucralose (brand name Splenda), are very commonly found in products such as diet soft drinks. Recently, researchers learned that these sweeteners may affect hormones in the body, especially when they are consumed in combination with real sugar. Changes in hormone levels may, in turn, result in changes in blood sugar, appetite, and weight. Researchers are interested in studying the effects of artificial sweeteners on the metabolism and hormonal levels of healthy volunteers.

Objectives:

• To study the effects that artificial sweeteners have on hormone levels, blood sugar, and appetite.
• To evaluate whether artificial sweeteners change the rate at which food passes out of the stomach into the gut, or the rate at which the body absorbs sugar from the gut.
• To evaluate the effects that different amounts of artificial sweeteners have on hormone levels.

Eligibility:

• Healthy volunteers between 18 and 45 years of age.

Design:

• This study will require one screening visit and four testing visits, scheduled on different days.
• At the screening visit, eligible participants will be screened with a physical examination, medical history, blood samples, and body measurements (including height, weight, body circumferences, and skin folds). Participants will also be asked about how much artificial sweetener they typically consume and will have taste tests, in which a small amount of flavored liquid is placed on the tongue and participants will name the flavor and rate its intensity.
• Participants will have four glucose tolerance tests on four different days. In preparation for the test, participants will not eat or drink anything but water for 12 hours prior to the test. Blood will be drawn before the test, and participants will drink one of the following study liquids, selected at random:
• Plain water
• Water mixed with sucralose (the amount found in one 12 oz diet soft drink)
• Water mixed with sucralose (the amount found in 2.5 12 oz diet soft drinks)
• Water mixed with sucralose (the amount found in 3.7 12 oz diet soft drinks)
• Ten minutes after drinking the study liquid, participants will have a sugary drink that will allow researchers to measure sugar absorption and the speed with which food leaves the stomach.
• In addition, participants will complete questionnaires about hunger levels before drinking the sugar solution and at regular intervals for 2 hours afterward. Blood samples will be taken at regular intervals as well.