The Effects of the Food Preservative Propionic Acid in Post-prandial Metabolism (Walnut)

Pilot Study to Study the Effects of the Food Preservative Calcium Propionate on Postprandial Hormonal and Metabolic Milieu

Propionic acid (PA) is used as a preservative in foods such as cheeses, baked goods, or additive for artificial fruit flavors. The U.S. Environmental Protection Agency considers it safe and therefore, has no limitation on its use. Since PA has been shown before to serve as a substrate for glucose production in the liver, the purpose of this study is to find out if PA intake causes changes in levels of glucose, insulin and other important hormones following a meal. This research study will compare PA to placebo. The placebo looks exactly like the active substance, but it does not contain any active agent (PA). Placebos are used in research studies to see if the results are due to the study drug or to other reasons. The investigators plan to have 20 subjects take part in this study at the Brigham and Women's Hospital (BWH).

-To test whether PA, added as food supplement to humans, results in altered post-prandial metabolism. The investigators propose to conduct a double-blind, randomized, placebo controlled, cross-over study in which blood levels of metabolites and hormones will be measured in healthy volunteers following a mixed meal test without or with PA. Study design: This is a double-blind, randomized, placebo controlled, cross-over study. Twenty volunteers who meet the inclusion/exclusion criteria will be randomized into two groups, provided with a mixed meal without or with calcium proprionate (also known as E282). A week later, participants will be provided with a mixed meal again, following cross-over of the groups. Blood will be collected at baseline, and every 30 minutes for 4 hours. Study Subjects: 20 healthy male and female volunteers (ages 18 to 65 years) with a body mass index (BMI) of 20 to <30 Kg/m2.

Addition of calcium propionate (PA arm) in a capsule (1000 mg) consumed together with a mixed meal of 500 kCal in the morning following an overnight fast. Blood is taken at baseline and every 30 minutes for 4 hours. This arm is compared to a placebo capsule (following identical protocol). Following a washout period of a week, the arms will be crossed over and the PA arm participants will repeat the same protocol in the 'placebo arm'.

Addition of placebo (PA arm) in a capsule consumed together with a mixed meal of 500 kCal in the morning following an overnight fast. Blood is taken at baseline and every 30 minutes for 4 hours. This arm is compared to the PA arm (PA, 1000 mg in a capsule). Following a washout period of a week, the arms will be crossed over and the PA arm participants will repeat the same protocol in the 'placebo arm', and vice versa.

Inclusion Criteria: Age 18-65 years Good health as evidenced by history and physical exam BMI: 20-29.9 kg/m2 Exclusion Criteria: Fasting plasma glucose >110 mg/dL HbA1c >6.0% Significant current illness other than treated hypothyroidism BP >135/85 or systolic BP <90 mm Hg Hepatic disease (transaminase > 3 times normal) Renal impairment (Creatinine clearance <60 ml/min) History of drug or alcohol abuse Participation in any other concurrent clinical trial Pregnant women History of food allergies.