Table 3.
Studies examining various interventions with OO consumption and their beneficial outcomes, consequence of OO’s antioxidant properties.
| Study Design | Compound | Intervention | Outcomes/ Biomarkers |
Results | Reference |
|---|---|---|---|---|---|
| RCT, parallel-group, multicenter, from the PREDIMED study on 75 metabolic syndrome patients, age: 55–80 years old |
EVOO | 5 years of intervention, 3 groups: MedDiet + EVOO (50 g/day), MedDiet + nuts (30 g/day), low-fat diet |
Antioxidant capabilities and xanthine oxidase activity | MedDiet + EVOO and MedDiet + nuts decreased xanthine oxidase activity and increased superoxide dismutase and catalase levels and antioxidant activities | [93] |
| Experimental on 11 overweight and non-insulin treated T2D Caucasian patients, 7 men and 4 women, mean age: 64.63 ± 8.52 years old, diabetes duration ≤10 years |
ROO HP-EVOO |
8 weeks: intake of ROO (25 mL/day) for the first 4 weeks (wash-out period) followed by intake of HP-EVOO (25 mL/day) for the rest of 4 weeks | Anthropometric parameters, fasting plasma glycaemia, HbA1c, CRP, plasma lipid profile, liver function, and serum levels of TNF-α, adiponectin, IL-6, visfatin, apelin |
HP-EVOO consumption reduced fasting glucose, HbA1c, BMI, body weight, AST, ALT, and visfatin | [91] |
| RCT, parallel group, single-center study on 77 T2D women, age: >50 years old; mean BMI 28 kg/m2 |
OO | 8 weeks, 3 groups: balanced diet + 30 g/day of OO or CO or SFO |
Height, weight, waist circumference, fasting blood sugar, serum insulin, CRP, MDA |
CRP level was reduced significantly in OO and CO groups | [92] |
| Two-arm study on 18 overweight/obese subjects (BMI ≥ 25 kg/m2) + 18 normal weight controls (BMI 18.5–24.9 kg/m2) | HQ-EVOO | MedDiet enriched with 40 g/day of HQ-EVOO for 3 months | Lactic acid bacteria composition, oxidative stress, metabolic and inflammation parameters | MedDiet rich in HQ-EVOO increased lactic acid bacteria numbers, decreased oxidative stress and inflammation parameters, and increased adiponectin and IL-10 concentrations | [95] |
| RCT double-blind, crossover, NUTRAOLEOUM study on 51 healthy adults |
VOO OVOO FOO |
VOO, OVOO and FOO (30 mL/day) were sequentially administered over three periods of 3 weeks preceded by 2-week washout periods | Oxidative and inflammatory biomarkers. | Urinary 8-hidroxy-2′-deoxyguanosine, plasma IL-8 and TNF-α were lower after the intervention with the FOO than after the OVOO. IL-8 was lower after the intervention with FOO than after VOO intervention. |
[97] |
| RCT, crossover on 30 patients with IFG, 17 men + 13 women, mean age: 58 years-old |
EVOO | Taking a meal with or without 10 g of EVOO | LPS, Apo-B48, ox-LDL, sNox2-dp, plasma polyphenols | EVOO significantly decreased LPS, ox-LDL, sNox2-dp and plasma polyphenols | [98] |
| RCT, double-blind, crossover study on 8 male trained cyclists, age: 34–45 years-old |
EVOO | Four-week supplementation of n-3 PUFA (5.7 g/day) or EVOO (6 g/day), followed by a four-week washout and crossover to the other supplement | Global and gene-specific (PPARGC1A, IL6 and TNF) DNA methylation, and DNMT1 mRNA expression |
EVOO decreased the methylation of the gene encoding IL-6 and the expression of DNMT1 | [99] |
| RCT double-blind, crossover, OLIVAUS study on 43 healthy Australian adults, age: 38.5 ± 13.9 years old, 66% females |
High Polyphenol Extra-Virgin Olive Oil (HPOO—320 mg/kg PC) Low Polyphenol Extra-Virgin Olive Oil (LPOO—86 mg/kg PC) |
Consumption of 60 mL/day of HPOO or LPOO for 3 weeks. Following a 2-week wash-out period, participants crossed-over to the alternate treatment | Anthropometric parameters, TAC, plasma oxLDL, CRP |
After HPOO consumption it was observed a reduction in ox-LDL and CRP and an increase in TAC, although there were no significant differences between treatments | [94] |
| RCT single-blind, crossover study on 25 T2D patients, 12 men + 13 women, age: 61–77 years-old |
EVOO | One single intake of 40 g of EVOO-enriched chocolate or 40 g of control chocolate spread. After a 10 days washout phase, participants crossed over to take the opposite chocolate | Endothelial function and oxidative stress | EVOO-enriched chocolate is associated with increased endothelial function and reduction of oxidative stress (decreasing sNox2-dp) | [65] |
| RCT double-blind study on 62 patients with major depression, age: 18–65 years-old |
EVOO | 52 days, during which participants consumed 25 mL/day of EVOO or SFO | Weight, BMI, waist circumference. TG, TC, LDL, HDL, Very Low-Density Lipoprotein Cholesterol (VLDL), MDA, CRP | EVOO significantly decreased waist circumference and significantly increased HDL | [100] |
| RCT in 149 severely obese individuals aged 18–65 years | EVOO | 2 groups: nutritional EVOO and DieTBra+EVOO followed for 12 weeks | Inflammation profiles, neutrophil-to-lymphocyte ratio, LMR, leukocytes, and CRP | DieTBra+EVOO was able to significantly decrease the total leukocytes and LMR. DieTBra showed a minimal decrease in neutrophil-to-lymphocyte ratio. EVOO and DieTBra interventions decreased CRP. It was also noted that the total leukocytes and LMR were similarly reduced in all groups. | [96] |
(ALT: Alanine Aminotransferase; Apo B-48: Apolipoprotein B-48; AST: Aspartate Aminotransferase; BMI: Body Mass Index; CO: Canola Oil; CRP: C Reactive Protein; DieTBra: Traditional Brazilian Diet; DNMT1: DNA Methyltransferase-1; EVOO: Extra-Virgin Olive Oil; FOO: Functional Olive Oil; Hba1c: Glycated Hemoglobin; HDL or HDL-C: High-Density Lipoprotein-Cholesterol; HP-EVOO: High-Polyphenol Extra-Virgin Olive Oil; HPOO: High Polyphenol Extra-Virgin Olive Oil; HQ-EVOO: High Quality EVOO; IFG: Impaired Fasting Glucose; IL: Interleukin; LDL or LDL-C: Low-Density Lipoprotein-Cholesterol; LMR: Lymphocyte-to-Monocyte Ratio; LP-EVOO: Low-Polyphenol Extra-Virgin Olive Oil; LPOO: Low Polyphenol Extra-Virgin Olive Oil; LPS: Lipopolysaccharides; MDA: Malondialdehyde; MedDiet: Mediterranean Diet; mRNA: messenger RNA; OO: Olive Oil; OVOO: Ordinary Virgin Olive Oil; Ox-LDL: Oxidized-LDL; PUFA: Polyunsaturated Fatty Acids; RCT: Randomized Control Trial; ROO: Refined Olive Oil; SFO: Sunflower Oil; sNox2-dp: Soluble NADPH oxidase 2-Derived Peptide; T2D: Type 2 Diabetes; TAC: Total Antioxidant Capacity; TC: Total Cholesterol; TG: Triacylglycerols; TNF-α: Tumor Necrosis Factor Alpha; VLDL: Very Low Density Lipoprotein Cholesterol; VOO: Virgin Olive Oil).