The PI will be leaving the institution and not continuing the study

This study will test the effect of short-term, high-dose dietary serine supplementation on circulating levels of serine. Individuals with risk factors for type 2 diabetes will be recruited into the 2 week study. Effects of dietary serine supplementation on glycemic measures will also be explored.

This is a single-center, open-label, randomized, nutritional intervention study in adults. Subjects will have three visits to the Massachusetts General Hospital Clinical Research Center (CRC) during the 2 week study.

At the first study visit (Visit 1), the following will occur: informed consent; medical and nutritional history assessment; blood pressure, weight and height, fasting blood draw and blood work during a 2 hr oral glucose tolerance test; explanation and instructions for completion of a 4-day food log; randomized assignment to dose of dietary serine supplementation (6g, 12g, 24g, or 48g); provide 7 days of dietary serine supplements; take first dose of supplement with snack; schedule Visit 2 and Visit 3.

Between Visit 1 and Visit 2, participants will complete the Food Log and take the assigned dose of dietary serine supplementation 3 times daily.

Visit 2 will occur 7 days after Visit 1. Subjects will not take dietary serine supplementation prior to Visit 2 activities. At Visit 2, the following will occur: weight and blood pressure; fasting blood draw; administration of assigned dose of dietary serine supplementation with snack after blood work; review of the 4-day food log; provide 7 days of dietary serine supplements completion of anonymous survey to assess tolerability of supplement. Participants will continue to take the assigned dose of dietary serine supplementation 3 times daily between Visit 2 and Visit 3.

Visit 3 will occur 7 days after Visit 2. At Visit 3, the following will occur: weight and blood pressure; review of the 4-day food log; fasting blood draw and blood work during a 2 hr oral glucose tolerance test; completion of study survey to assess tolerability of the supplement.

Inclusion Criteria:

• risk factors for type 2 diabetes

Exclusion Criteria:

• known type 2 diabetes
• women who are pregnant, nursing, or not using contraception or abstinence
• taking amino acid supplements during the study or at any time 1 month prior to enrollment in the study
• conditions causing intestinal malabsorption, including celiac disease or a history of intestinal or gastric bypass surgery
• known active liver disease
• currently taking or intending to take during the study duration any medication known to affect glycemic parameters, such as glucocorticoids, growth hormone, or fluoroquinolones
• participation in any other interventional study during the study duration
• inability to adhere to study protocol.