Data from 33 people with elevated blood lipid levels (hyperlipidemic) indicated that consumption of virgin olive oil enriched with polyphenols from thyme significantly decreased levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG), a marker for DNA damage.
“The significant decrease in urinary 8-OHdG after [virgin olive oil complemented with thyme phenolic compounds] consumption suggests that olive and thyme phenolic compounds could act synergistically as bioactive molecules protecting against oxidative DNA damage and improving oxidative systemic balance as reflected also in the increase of erythrocyte SOD [superoxide dismutase, an endogenous antioxidant enzyme] activity,” wrote the researchers in the Journal of Agricultural and Food Chemistry.
The researchers performed a randomized, double-blinded, crossover, controlled trial with 33 hypercholesterolemic people aged between 35 and 80. The participants were randomly assigned to consume 25 mL per day of one of three olive oil forms: virgin olive oil (providing 2.88 mg total phenols per day); virgin olive oil enriched with olive polyphenols (providing 12.59 mg total phenols per day); or the same virgin oil enriched with olive and thyme polyphenols (providing 12.10 mg total phenols per day). Each intervention lasted three weeks, and was followed by a two week washout before crossing over to a different intervention.
Results showed that the decrease in 8-OHdG was 10-fold higher in the virgin oil enriched with olive and thyme polyphenols and 5-fold higher in the virgin olive oil enriched with olive polyphenols groups, compared with the virgin olive oil control group.
In addition, SOD activity increased in both enriched olive oil groups, with the greater increase in the thyme enriched oil, said the researchers.
“When all three oils were compared, [virgin oil enriched with olive and thyme polyphenols] appeared to have the greatest effect in protecting against oxidative DNA damage and improving [the antioxidant endogenous enzymatic system],” they wrote.
Commenting on the potential mechanism, the researchers noted that the polyphenols may inhibit the action of NF-kappaB, which would reduce the production of reactive oxygen species and protect lipids and DNA from oxidative damage.
“The suppression of the NF-kappaB pathway by thyme phenolic compounds could be sufficient to reduce the endogenous DNA damage produced naturally by cells. Further studies are needed to verify this mechanistic pathway responsible for the protective antioxidant effect observed in humans.”
Source: Journal of Agricultural and Food Chemistry
Published online ahead of print, doi: 10.1021/acs.jafc.5b04915
“Virgin Olive Oil Enriched with Its Own Phenols or Complemented with Thyme Phenols Improves DNA Protection against Oxidation and Antioxidant Enzyme Activity in Hyperlipidemic Subjects”
Authors: M. Romeu