Effects of a Food Preservative on Glucose Homeostasis
Condition: Overweight
MeSH terms: Overweight
Study type: Interventional

Summary: 
      The investigators propose to examine the effects of the common food preservative sodium
      benzoate on blood glucose and related hormones and metabolites. If an effect is demonstrated,
      patients with increased diabetes risk could be counseled to avoid this preservative.
    

Detailed description: 
      Soft drink consumption has been repeatedly implicated in the development of type 2 diabetes
      (T2DM). Interestingly, epidemiology studies have yielded inconsistent results. Some studies
      identify sugar-sweetened beverages as the culprit, whereas others point towards
      artificially-sweetened beverages. Beyond differences in methodology, these conflicting
      reports raise the question whether another ingredient common to both sugar and
      artificially-sweetened soft drinks, such as a preservative, might play a role.

      Benzoate salts are widely used preservatives in products such as sodas, canned goods, and
      pharmaceuticals. Interestingly, there is published evidence that sodium benzoate and its
      metabolite hippurate can affect pancreatic islet function and impair glucose tolerance.
      However, the effects of oral sodium benzoate at concentrations typically used in our diet on
      glucose homeostasis have not been systematically studied. Here, we propose to close this
      knowledge gap.

      We will recruit 15 healthy, overweight volunteers, age 18-35. Each subject will receive 4
      interventions: an oral glucose challenge 1) with and 2) without 0.1% benzoic acid, and a
      drink of water 3) with and 4) without 0.1% benzoic acid. Blood samples will be analyzed for
      glucose, insulin, glucagon, and a panel of approximately 300 different metabolites at
      baseline and serially for 2 hours after each intervention. Factorial analysis of variance
      will be performed to determine the effects of benzoic acid in the presence and absence of
      glucose, and interactions between glucose and benzoate. The planned sample size of 15 will
      provide 80% power to detect an effect-size of 0.16 standard-deviations in outcome measures,
      and an interaction-effect of 0.33 standard-deviations, with a critical value p=0.05.

      If we find through this study that sodium benzoate significantly affects glucose tolerance,
      the public health implications would be great. High level, frequent consumption might cause
      diseases associated with insulin resistance, chiefly T2DM. Furthermore, its presence in OGTT
      testing solutions could provide misleading results.
    

Intervention name(s): benzoate containing test drinks; non sodium benzoate containing test drinks
Intervention type(s): Other; Other
Intervention description(s): Subjects will consume 500ml of water with 0.5 grams of sodium benzoate, followed by a solution of 75g sugar in 500ml water with 0.5 grams sodium benzoate 3 hours later.
Each solution will be consumed over 5 minutes.; Subjects will consume 500ml of water followed by a solution of 75g sugar in 500ml water 3 hours later.
Each solution will be consumed over 5 minutes.
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Triple (Participant, Care Provider, Investigator)
Primary purpose: Prevention
Keywords: diabetes; benzoic acid; benzoate; soda; soft drink; preservative; blood sugar