Olive Oil Polyphenols and Cardiovascular Health Biomarkers

The purpose of this research is to investigate whether consuming two different kinds of olive oil will change risk factors related to cardiovascular disease, including levels of good and bad cholesterol, levels of inflammation, and levels of gene expression. Healthy individuals aged 20-45 with a BMI over 20 kg/m2 are eligible to participate. The study involves 5 visits (1 initial screening and 4 study visits) and will last about 8 weeks. There is a 2-week run-in period before starting the study, followed by two diet intervention periods each lasting two weeks, separated by a two-week washout period.

Participation in this study will involve an initial two-week run in period to become accustomed to the study diet. After this two week period, participants will be randomly selected to start either a high-polyphenol olive oil (extra virgin olive oil) or a low-polyphenol olive oil (refined olive oil); participants will consume the other oil during the second dietary intervention period lasting 2 weeks. During each phase of the study, participants will be asked to come to the University of California, Davis campus after a 10-12 hour overnight fast. At each visit, body measurements will be taken, a serving of olive oil and bread will be eaten, and three urine and blood samples will be collected over the course of 4 hours. Each study visit will involve three blood draws by a trained nurse or phlebotomist.

During the 8 weeks of the study, all olive products such as olives, olive oil, and olive containing products will need to be avoided. The study will provide olive oil to be eaten at home for each intervention phase. Additionally, the investigators will ask that nuts and high-polyphenol foods (mostly fruits and vegetables) be avoided in the diet. Detailed food diaries will be filled out and brought to study visits.