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Table 1 Characteristics of eligible randomized controlled trials that investigated the effect of OLE intervention on cardiovascular-risk factors in adults

From: The effects of olive leaf extract on cardiovascular risk factors in the general adult population: a systematic review and meta-analysis of randomized controlled trials

Author, year

Country

Participants (I, C)/sex

Design/duration (weeks)

Mean age

Health status

Intervention protocol/control protocol

Outcome

Obesity

HTN

Dyslipidemia

T2DM

Other

Araki, 2019 [19]

Japan

(28, 29)/B

P/12

52

Y

N

N

Y

–

1000 ml OLT (32.4 mg/100 g Oleuropein, 1.2 mg/100 g Hydroxytyrosol)/0.5 g LOLT ((2.4 mg/100 g Oleuropein, 0.3 mg/100 g HT)

FBS, HbA1c, HOMA-IR, LDL-C, HDL-C,

Araki, 2018 [34]

Japan

(20, 19)/B

P/12

52

N

N

Y

N

–

1000 ml OLT (425 mg/L Oleuropein,6.4 mg/L Hydroxytyrosol)/Green tea (0 mg/L Oleuropein, and 4.9 mg/L Hydroxytyrosol)

FBS, HbA1c, LDL-C, HDL-C, TG

de Bock, 2013 [20]

New Zealand

(45, 45)/M

C/12

46.5

Y

N

N

N

–

4 Cap (51.1 mg Oleuropein, 9.6 mg HT)/ Pl

LDL-C, HDL-C, TG, TC, SBP, DBP, hs-CRP, IL-6, IL-8, TNF-α, LDL-ox,

Filip, 2015 [42]

Netherlands

(32, 32)/F

P/48

59.7

N

N

N

N

Postmenopausal women with osteopenia

250 mg Cap (40% ≤ Oleuropein) + 400 mg Ca/400 mg Ca

LDL-C, HDL-C, TG, TC, hs-CRP, IL-6, ALP, Cr

Javadi, 2019 [35]

Iran

(30, 30)/B

P/12

54

N

Y

N

N

–

500 mg Tab (16% Oleuropein, 0.62 mg luteolin)/Pl

FBS, Ins, HOMA-IR, IL-6, IL-8, TNF-α, AST, ALT, ALP, Cr

Lockyer, 2017 [17]

Australia

(31, 30)/M

C/6

45.3

Y

Y

N

N

–

20 ml/day OLE liquid (equaled to 136.2 mg/day oleuropein and 6.4 mg/day Hydroxytyrosol)/Pl

FBS, Ins, HOMA-IR, LDL-C, HDL-C, TG, TC, SBP, DBP, hs-CRP, IL-6, IL-8, TNF-α, LDL-ox

Perrinjaquet-Moccetti, 2008 [21]

Switzerland

(10, 10)/B

P/8

36

N

Y

N

N

–

500 mg Tab OLE (e 18–26%) oleuropein, 30–40% polyphenols and luteolin-7-glucoside)/Pl

LDL-C, HDL-C, TC, SBP, DBP

Saberi, 2018 [24]

Iran

(32, 32)/B

P/NM

54

N

Y

N

N

–

1000 mg Cap OLE/Pl

SBP, DBP,

Stevense, 2021 [43]

Netherlands

(39, 38)/B

P/8

56.5

Y

N

Y

N

–

500 mg OLE (16.7%, and 83.5 mg oleuropein)/Pl

FBS, Insulin, LDL-C, HDL-C, TG, TC, SBP, DBP, LDL-ox, AST, ALT, ALP

Susalit, 2011 [36]

Indonesia

(72, 76)/B

P/8

50

N

Y

N

N

–

500 mg Caplet (19.9%) oleuropein)/12.5 mg captopril

FBS, Insulin, LDL-C, HDL-C, TG, TC, AST, ALT, Cr, SBP, DBP

Wainstein, 2012 [44]

Israel

(41, 38)/

P/14

 ≥ 55

N

N

N

Y

–

500 mg Tab OLE /Pl

HbA1c

Yaghoobzadeh, 2020 [37]

Iran

(30, 30)/B

P/12

54.5

N

Y

N

N

–

500 mg Tab OLE (16% and 0.6 luteolin)/Pl

LDL-C, HDL-C, TG, TC, SBP, DBP

  1. P, parallel design; C, crossover design; HTN, hypertension; T2DM, type-2 diabetes mellitus; OLT, olive leaf extract; OLT, olive leaf tea; LOLT, low concentration of olive leaf tea; FBS, fasting blood glucose; HbA1c, glycated hemoglobin; HOMA-IR, homeostatic model assessment for insulin resistance; LDL-C, low-density lipoprotein cholesterol; HDL-C, high-density lipoprotein cholesterol; TG, triglycerides; TC, total cholesterol; SBP, systolic blood pressure; DBP, diastolic blood pressure; hs-CRP, high-sensitivity C-reactive protein; IL-6, interleukin-6; IL-8, interleukin-8; TNF-α, tumor necrosis factor alpha; LDL-ox, oxidized low-density lipoprotein; AST, aspartate transaminase; ALT, alanine transaminase; ALP, alkaline phosphatase; Cr, creatinine; Cap, capsule; Tab, tablet; Ca, calcium, PI, per intervention