Oral Supplementation with Hydroxytyrosol Synthesized Using Genetically Modified Escherichia coli Strains and Essential Oils Mixture: A Pilot Study on the Safety and Biological Activity.

Several natural compounds have been explored as immune-boosting, antioxidant and anti-inflammatory dietary supplements. Amongst them, hydroxytyrosol, a natural antioxidant found in olive products, and endemic medicinal plants have attracted the scientific community's and industry's interest. We investigated the safety and biological activity of a standardised supplement containing 10 mg of hydroxytyrosol synthesized using genetically modified Escherichia coli strains and equal amounts (8.33 μL) of essential oils from Origanum vulgare subsp. hirtum , Salvia fruticosa and Crithmum maritimum in an open-label, single-arm, prospective clinical study. The supplement was given to 12 healthy subjects, aged 26-52, once a day for 8 weeks. Fasting blood was collected at three-time points (weeks 0, 8 and follow-up at 12) for analysis, which included full blood count and biochemical determination of lipid profile, glucose homeostasis and liver function panel. Specific biomarkers, namely homocysteine, oxLDL, catalase and total glutathione (GSH) were also studied. The supplement induced a significant reduction in glucose, homocysteine and oxLDL levels and was tolerated by the subjects who reported no side effects. Cholesterol, triglyceride levels and liver enzymes remained unaffected except for LDH. These data indicate the supplement's safety and its potential health-beneficial effects against pathologic conditions linked to cardiovascular disease.