Effect of virgin olive oil and thyme phenolic compounds on blood lipid profile: implications of human gut microbiota.

PURPOSE: To investigate the effect of virgin olive oil phenolic compounds (PC) alone or in combination with thyme PC on blood lipid profile from hypercholesterolemic humans, and whether the changes generated are related with changes in gut microbiota populations and activities. METHODS: A randomized, controlled, double-blind, crossover human trial (n = 12) was carried out. Participants ingested 25 mL/day for 3 weeks, preceded by 2-week washout periods, three raw virgin olive oils differing in the concentration and origin of PC: (1) a virgin olive oil (OO) naturally containing 80 mg PC/kg, (VOO), (2) a PC-enriched virgin olive oil containing 500 mg PC/kg, from OO (FVOO), and (3) a PC-enriched virgin olive oil containing a mixture of 500 mg PC/kg from OO and thyme, 1:1 (FVOOT). Blood lipid values and faecal quantitative changes in microbial populations, short chain fatty acids, cholesterol microbial metabolites, bile acids, and phenolic metabolites were analysed. RESULTS: FVOOT decreased seric ox-LDL concentrations compared with pre-FVOOT, and increased numbers of bifidobacteria and the levels of the phenolic metabolite protocatechuic acid compared to VOO (P < 0.05). FVOO did not lead to changes in blood lipid profile nor quantitative changes in the microbial populations analysed, but increased the coprostanone compared to FVOOT (P < 0.05), and the levels of the faecal hydroxytyrosol and dihydroxyphenylacetic acids, compared with pre-intervention values and to VOO, respectively (P < 0.05). CONCLUSION: The ingestion of a PC-enriched virgin olive oil, containing a mixture of olive oil and thyme PC for 3 weeks, decreases blood ox-LDL in hypercholesterolemic humans. This cardio-protective effect could be mediated by the increases in populations of bifidobacteria together with increases in PC microbial metabolites with antioxidant activities.

Oxidized low-density lipoprotein antibodies in myocardial infarction patients without classical risk factors.

AIM: To determine whether circulating antibodies against oxidized low-density lipoprotein (LDL; OLAB) levels are associated with acute myocardial infarction (AMI) in individuals without classical cardiovascular risk factors. METHODS: A case-control study including 34 first AMI patients without classical risk factors (smoking, dyslipidemia, hypertension or diabetes) and 45 population-based healthy controls. RESULTS: There were no differences in anthropometric variables between cases and controls. Oxidized LDL levels were similar in both groups. Total cholesterol, LDL cholesterol, apolipoprotein B and physical activity were lower in cases than in controls. OLAB levels were also lower in cases than controls (128 versus 447 U/l, P < 0.001). After adjusting for age, oxidized LDL and physical activity, participants with OLAB levels of 165 U/l or less had a higher risk of AMI (odds ratio, OR = 7.48, 95% confidence interval: 1.57-35.66). When the model was fitted with OLAB as a continuous variable, the natural logarithm (LnOLAB) levels were independently associated with AMI with an OR of 0.40 (95% confidence interval: 0.19-0.86). After adjusting the model by Framingham-risk-adapted score and oxidized LDL, the LnOLAB levels maintained their independent association (OR of 0.43, 95% confidence interval: 0.23-0.79). CONCLUSION: First AMI patients without classical risk factors had lower levels of OLAB compared with healthy controls. It is likely that the immunological reaction due to oxidized LDL participates as a preventive factor in the physiopathology of atherosclerosis.