The study aims to evaluate the novel OptiCreatine formulation, which combines creatine with other bioactive compounds purported to enhance absorption and reduce gastrointestinal (GI) discomfort. Using a randomized, double-blind, crossover design, the study will compare the acute and chronic effects of OptiCreatine versus Creatine monohydrate in healthy, recreationally active adults. Participants will be asked to orally consume both the OptiCreatine and the creatine monohydrate. Primary outcomes include plasma creatine concentrations, gastrointestinal symptomatology, and fluid distribution measured through bioelectrical impedance spectroscopy.

The study aims to evaluate the novel OptiCreatine formulation, which combines creatine with other bioactive compounds purported to enhance absorption and reduce gastrointestinal (GI) discomfort. The study objectives are as follows:

• Aim 1: To examine the acute effects of OptiCreatine compared to creatine monohydrate on plasma creatine concentrations and gastrointestinal symptoms.
• Aim 2: To example the effects of 5-days of creatine loading with OptiCreatine compared to creatine monohydrate on gastrointestinal symptoms and fluid distribution.

General Design: All data collection will be completed by the Principal Investigator and Research Assistants at the University of North Carolina. Participants will be asked to report to the Applied Physiology Laboratory and Human Performance Center for enrollment and testing sessions. Thirty-two individuals total will be enrolled into the study. Sixteen participants will be enrolled into the acute phase; Sixteen will be enrolled into the chronic phase with random assignment to OptiCreatine (n=8) or creatine monohydrate (n=8). Participants from the acute phase are eligible to enroll into the chronic phase. The acute phase will require 2 in person visits, in random order, with participants randomly assigned in a cross-over fashion to OptiCreatine vs creatine monohydrate. Blood samples will be obtained at baseline and at 0.5, 1, 1.5, 2, 3, 4, and 5 hrs. following ingestion of the assigned treatment. A minimum of 72 hrs. will take place in between acute visits. For the chronic phase, participants will complete baseline assessments for GI symptoms via questionnaires (bloating questionnaire, gastrointestinal symptom rating scale, digestion associated quality of life questionnaire) and fluid distribution from multi-frequency bioelectrical impedance analysis (MF-BIA). Following baseline testing, participants will be randomly assigned to an OptiCreatine or creatine monohydrate group. Post testing evaluation will occur within 48 hours of the 5-day loading phase.

Supplementation Phase:

• Acute: In a randomized double-blind, cross-over design study, participants will be randomly assigned using a using a computer-generated randomization scheme to consume either OptiCreatine (5 g + 6 oz water, n=8) or creatine monohydrate supplement (5 g + 6 oz water, n=8). All participants will complete both treatments, including a minimum of a 3-day washout period.
• Chronic: In a randomized double-blind design study, participants will be randomly assigned using block randomization in a 1:1 fashion using a computer generation randomization scheme to participants in a creatine loading dose (4 x 5 grams daily- 20 g per day for 5 days) of OptiCreatine or creatine monohydrate.

Participants will be asked to arrive at the laboratory for all visits after a minimum 8-hour fast from caloric foods and beverages, 48-hour abstention from vigorous exercise, and 24-hour abstention from caffeine consumption. Participants will be asked to maintain normal dietary intake along with no more than 200mg of caffeine per day for the duration of the study. Measurements of anthropometrics, GI symptoms, and fluid distribution will be obtained. For the acute phase, blood samples will be taken from the antecubital region.

Inclusion Criteria:

• Adults between the ages of 18-45 yrs
• Body mass index of <35 kg/m2
• Recreationally active [≥30 minutes of moderate-intensity physical activity per week as defined by the International Physical Activity Questionnaire (IPAQ)]
• Participant is healthy and free from disease as determined by a health history questionnaire.
• Participant agrees to abstain from caffeine (24 hrs. prior), tobacco (24 hrs. prior), and alcohol (24 hrs. prior) before testing days

Exclusion Criteria:

• Has chronic kidney disease, liver disease, chronic obstructive pulmonary disease, or cancer
• Currently using medications that may directly impact the primary outcomes including: diuretics and corticosteroids)
• Currently using creatine monohydrate
• Has severely impaired hearing or speech or inability to speak English