The purpose of this study is to determine whether taking certain drugs (metformin or trimethoprim) and a vitamin (thiamine) together affects your body’s ability to absorb, distribute and eliminate thiamine (aka vitamin B1), which is an essential vitamin necessary for the body to stay healthy.
Men and women, aged 18-65 years old
• BMI >35 kg/m2
• Chronic diseases
• Any prescription medication
• Regular use of any dietary supplements containing vitamins and minerals; however, subjects who are willing to refrain from the use of these supplements for 4 weeks prior to their enrollment and throughout the entire study may be considered eligible; subjects will be excluded if they are taking physician prescribed vitamin and/or mineral supplements
• Vegetarian or vegan
• Smoking tobacco products or use of nicotine replacement products in the last 12 months; or smoking marijuana (incl. consumption of edibles) in the last week
• Pregnancy or breastfeeding
Length of Study
Number of Visits
One screening visit; three cycles of three visits with 5-14 days in-between cycles. Each cycle will consist of one visit to record vitals and pick up food for that day (about 1-2 hours); one 14-hour visit consisting of drug administration, vitals, blood draws and urine collections; one visit to record vitals and submit overnight urine kit (about 1 hour).
Can I work?
Yes, but not on the days when you will need to be at the HNRCA for 14 hours. If subjects employed by Tufts University qualify to participate in the study, they cannot participate as volunteers during hours in which they are being compensated by Tufts University for their regular work. This includes the use of vacation, personal days and sick time.
Subjects must maintain their regular diet throughout the trial, except for the total of 6 days (2 days per cycle) during which participants will be required to consume only meals provided by the Jean Mayer USDA Human Nutrition Research Center on Aging (HNRCA). Participants will also be required to consume different combinations of metformin, trimethoprim and thiamine provided by the HNRCA during three, 14-hour visits in this study.
$25 for screening, and up to $1,000 for participants who qualify and complete the entire study