2.2. Study Design and Dietary Intervention
AIDS, MINOR
The 16-week dietary intervention utilized a randomized cross-over design. Following enrollment into the study, participants entered a 4-week egg-free diet run-in period, during which they were asked to refrain from consuming whole eggs, egg whites, or predominantly egg-based foods where egg fractions constituted more than a minor ingredient (egg-free diet). Participants were then randomly assigned to consume either 3 large shelled whole eggs/day (whole egg diet) or the equivalent of 3 large egg whites (0.5 cup liquid egg whites, Wholesome Farms, Sysco Corporation, Houston, TX, USA)/day (egg white diet) for 4 weeks. Participants then entered a 4-week egg-free washout period, followed by assignment to the alternative whole egg- or egg white-based diet treatment for the final 4 weeks of the intervention. All whole eggs and egg white food products were pasteurized and provided to the participants, who were asked to refrain from consuming any outside egg products. Whole eggs were provided as shelled eggs to provide participants with greater flexibility in preparation during the whole egg diet period, and 100% egg whites were provided in cartons during the egg white diet period. Egg white ingredients included egg whites, guar gum, and triethyl citrate as whipping aids. Participants were allowed to consume study eggs at any time of day using preferred cooking methods and instructed to fully cook eggs for food safety. Participants were asked to maintain their habitual dietary patterns, level of physical activity, and usage of supplements and medications throughout the duration of the study, all of which were monitored by surveys. Of note, approximately half of the female participants were taking combined oral contraceptive (COC) medication (n = 11, n = 10 non-users). Participants were weighed using a digital scale every two weeks to ensure weight maintenance throughout the intervention. A total of 29 individuals were screened for participation in the study. One individual did not meet the study criteria and was excluded from participating in the study. Twenty-eight participants (twenty-one female, seven male) met the study criteria and were enrolled into the study. Two participants (both male) withdrew for reasons unrelated to the study within the first few weeks of the egg-free diet period and were excluded from analyses. An overview of the study flowchart is presented in 