The Effect of Artificial Sweeteners (AFS) on Sweetness Sensitivity, Preference and Brain Response in Adults

We aim to identify neural factors that contribute to taste intensity perception in humans and
to determine environmental mechanisms that contribute to variation in taste sensitivity.
Significant controversy surrounds the possibility that consumption of artificial sweeteners
(AFS) leads to weight gain. Given that the five FDA approved AFSs are found in thousands of
foods (Yang 2010) this marks a clear and significant gap in knowledge. Our preliminary data
demonstrate a 3-fold decrease in sweet taste sensitivity following consumption of a beverage
sweetened with two packets of Splenda for just 10 days. These data provide strong evidence
that repeated exposure to sucralose reduces perception of sweet taste intensity, most likely
by down-regulation of the sweet taste receptor. Therefore, it is imperative that we gain a
greater understanding of the physiological consequences of AFS, since alterations in sweet
taste perception, metabolism and brain reward that occur in response to AFS exposure may
promote weight gain.

Inclusion Criteria:

- Healthy

- Fluent in English

- Right handed

Exclusion Criteria:

- History of oral nerve damage,

- presence of known taste or smell disorder,

- food allergies or sensitivities (for example nuts, lactose, artificial sweeteners),

- history of CNS disease,

- diabetes,

- history of DSM-IV major psychiatric disorder,

- including alcohol and substance abuse,

- chronic use of medication that may affect taste,

- conditions that may interfere with gustatory or olfactory perception (colds, seasonal
allergies,

- recent smoking history),

- aberrant stimulus ratings,

- contra-indication for fMRI,

- uncomfortable swallowing in supine position,

- discomfort or anxiety associated with insertion an intravenous catheter,

- regular artificial sweetener use.