Thyme-Enriched EVOO Prevents DNA Damage

Increasing antiox­i­dant sta­tus in people’s diets is an impor­tant strat­egy for decreas­ing the devel­op­ment and pro­gres­sion of many dis­eases such as car­dio­vas­cu­lar dis­ease, can­cer, dia­betes, neu­rode­gen­er­a­tive con­di­tions and oth­ers.

Phenolic com­pounds (PC) in extra vir­gin olive oil (EVOO) are well known for their antiox­i­dant sta­tus, being a bioavail­able real food source of these mol­e­cules that inhibit the oxi­da­tion of other mol­e­cules, and it can eas­ily be added to an indi­vid­u­al’s stan­dard daily intake. Protection against oxida­tive stress is ben­e­fi­cial for dis­ease pre­ven­tion.

A ran­dom­ized dou­ble-blind study, pub­lished in the Journal of Agricultural and Food Chemistry, aimed to deter­mine if enrich­ing EVOO with its own phe­no­lic com­pounds or that of other food sources, such as thyme, could improve the bioavail­abil­ity of EVOO and enhance its bio­log­i­cal prop­er­ties. The authors of the study sug­gest, ​“the pro­tec­tion of body cells and mol­e­cules such as DNA, pro­teins, and lipids from oxida­tive dam­age could be con­sid­ered as a ben­e­fi­cial phys­i­o­log­i­cal effect.”

To inves­ti­gate this, the study looked at the effect of two func­tional EVOOs, one sam­ple enriched with its own PC, the other sam­ple enriched with both its own PC and thyme PC. Primary out­comes were pro­tec­tion of oxida­tive stress as mea­sured by urine, plasma oxi­da­tion marker and ery­thro­cyte antiox­i­dant enzymes, simul­ta­ne­ously with the detec­tion of urine, plasma, and ery­thro­cyte phe­no­lic metabo­lites. Thirty-three hyper­c­ho­les­terolemic vol­un­teers (total cho­les­terol > 200 mg/dL) were ran­dom­ized to EVOO 25/ mL /day, EVOO enriched with its own PC with 2.88 mg total phenols/ day, or EVOO enriched with both its own PC and thyme PC with 12.10 mg total phe­nols / day.

The urine oxi­da­tion bio­marker 8‑OHdG has been widely used as a DNA dam­age indi­ca­tor in many nutri­tional stud­ies as it’s a major base formed after DNA oxida­tive dam­age. The reduc­tion in 8‑OHdG was EVOO 0.4 nM, EVOO enriched with PC ‑2.0 nM, and EVOO enriched with both PC and thyme PC ‑4.4 nM.

All olive oil sam­ples con­sisted of the same com­po­nents other than their PC con­tent. The study found that EVOO enriched with both its own PC and thyme PC ​“pro­vided major pro­tec­tion against oxida­tive DNA dam­age. The antiox­i­dant pro­tec­tion was also reflected in the activ­ity of antiox­i­dant enzymes in ery­thro­cytes… [There was] a par­al­lel increase in thyme phe­no­lic metabo­lites detected in both urine and ery­thro­cytes. Our data, there­fore, pro­vide the first level of evi­dence for an antiox­i­dant DNA action and antiox­i­dant enzy­matic induc­tion through a com­bi­na­tion of olive and thyme PC, after a sus­tained con­sump­tion of real-life doses of olive oil in hyper­lipi­demic sub­jects.”

To clar­ify the mech­a­nisms behind these effects, a par­al­lel exper­i­ment was per­formed in ani­mals (20 Wistar rats). The authors state, ​“It has been seen that hydrox­y­ty­rosol acts as an inhibitor of NF-κB acti­va­tion, lead­ing to the inhi­bi­tion of pro­lif­er­a­tion and pro­mo­tion of apop­to­sis in human hepa­to­cel­lu­lar car­ci­noma cells. Furthermore, inhibit­ing NF-κB acti­va­tion reduces ROS pro­duc­tion and oxida­tive dam­age to lipids and DNA.”

However, they also sug­gest that thyme PC alone could be suf­fi­cient to reduce endoge­nous DNA dam­age, there­fore fur­ther stud­ies in this area are war­ranted.

Still, the fact that EVOO enriched with its own PC only also showed a ben­e­fi­cial effect over 8‑OHdG pro­vides sub­stan­tial evi­dence that enrich­ing EVOO could, in fact, be a suit­able way to enhance the level of antiox­i­dants in an individual’s every­day diet and, there­fore, reduce the preva­lence of dis­ease. If any­thing, it’s cer­tainly some­thing that is worth fur­ther explo­ration.

• Journal of Agricultural and Food Chemistry