Shogo Tsujino, Shohei Sadamitsu, Naohisa Nosaka, Tatsuya Fushimi, Yoshimi Kishimoto, Kazuo Kondo
Journal: Nutrients 2024;16(19):3342
PMID: 39408309
Oxidation of low-density lipoprotein (LDL) is a key factor in the development of atherosclerosis, a leading cause of death worldwide. The aim of this study was to investigate the effects of polyphenol-rich extra virgin olive oil (EVOO) on oxidation of LDL in Japanese men and whether these effects may be age-dependent. This double-blind randomised controlled crossover trial enrolled 80 healthy Japanese men aged 35-64 years. All participants started with a 14-day diet and lifestyle management period. This was followed by a 21-day intervention period, followed by a 14-day washout and another 21-day intervention period. The active intervention was 14 g EVOO containing 5.0 mg polyphenols whilst the control food was a refined olive oil containing 0.3mg polyphenols. Bloods were drawn at the start of the intervention periods and before and after a test meal on day 21. Outcome measures included malondialdehyde-modified LDL (MDA-LDL, a measure of oxidation status), small dense LDL (sdLDL, a marker associated with increased risk of myocardial infarction), potential antioxidant (PAO), total LDL, HDL and triglycerides (TG). Overall, there was no difference in changes in markers of LDL-oxidation and fat lipids between the test and the control groups. When stratified by age, in those aged 50 years and younger, MDA-LDL was significantly more reduced in the test group compared to control after but not before the test meal on day 21. sdLDL reduced significantly more in the control group whilst PAO and TG increased significantly more in the test group both before and after the test meal. There were no significant differences in total LDL and HDL cholesterol. There were no differences in any outcomes in participants above 50 years. This age group had a significantly higher intake of polyphenols in their habitual diet (by approximately 50%) compared to the younger participants. The authors discuss that the observed increase in sdLDL is likely associated with the increase in triglycerides, which tended to be lower in the test group at baseline.
BACKGROUND
The function of olive oil polyphenols in suppressing the oxidation of low-density lipoprotein (LDL) is well-known in Europeans. However, it remains unclear whether olive oil polyphenols exert antioxidant effects in Japanese people.
OBJECTIVES
The objective of this study was to determine whether the ingestion of olive oil polyphenols suppresses LDL oxidation in the Japanese population and whether this effect depends on age.
METHODS
This randomized controlled double-blind crossover trial with a 2-week washout enrolled 80 healthy Japanese men aged 35-64 years. Participants ingested either 14 g of extra virgin olive oil containing 5.0 mg of olive oil polyphenols (test food) or 14 g of refined olive oil containing 0.3 mg of olive oil polyphenols (control food) for 3 weeks. The primary outcome was oxidized LDL (malondialdehyde-modified LDL; MDA-LDL). Subgroup analyses based on age (35-50 and 51-64 years) were also performed.
RESULTS
In all of the participants (35-64 years), there were no significant differences in MDA-LDL between the control and test groups. However, in the 35-50 years subgroup, ingestion of olive oil polyphenols led to a significantly larger reduction in MDA-LDL as compared with the control group ( < 0.025).
CONCLUSIONS
The significantly lower dietary total polyphenol intake of the 35-50 years subgroup compared to the 51-64 years subgroup suggests that the suppressive function of olive oil polyphenol intake on LDL oxidation in Japanese men is influenced by dietary habits and is more clearly demonstrated in the younger age population with a relatively low total polyphenol intake.
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