Introduction
Materials and methods
Information sources and retrieval strategy
Eligibility criteria
Data extraction and quality evaluation
Data process and analysis
Quality of evidence and GRADE approach
Results
Research screening and description
Basic characterization and quality evaluation
Author year | Country | Trial design | Sample | Mean age | Baseline disease | Intervention | Dosage | Duration | Outcomes | |||
---|---|---|---|---|---|---|---|---|---|---|---|---|
T | C | T | C | T | C | mg/d | /w | |||||
Adler, A. J.,1997 [20] | Canada | parallel | 11 | 11 | 45.9 | 45.4 | hyperlipidemia | GT | placebo | 900 | 12 | TG,TC,LDL,HDL |
Aslani, N.,2016 [21] | Iran | parallel | 27 | 28 | 45.3 | 39.3 | hyperlipidemia | RG | none | 8 | BMI,TG,TC,LDL,HDL | |
Auer 1990 [22] | Germany | parallel | 24 | 23 | NR | NR | hypertension | GT | placebo | 600 | 12 | SBP,DBP |
Byrne, DJ.,1999 [23] | UK | parallel | 20 | 11 | NR | NR | hyperlipidemia | GT | placebo | 900 | 24 | TG,TC,LDL,HDL |
Gardner, CD.,2001 [24] | USA | parallel | 16 | 18 | 50.2 | 51.6 | hyperlipidemia | GT | placebo | 999 | 12 | TG,TC,LDL,HDL |
Higashikawa, F., 2012 [25] | Japan | parallel | 28 | 26 | 52 | 51.4 | hyperlipidemia | PG | placebo | 900 | 12 | BMI,TG,TC,LDL,HDL,FBG |
Isaacsohn, JL.,1998 [26] | USA | parallel | 24 | 18 | 58 | 57.4 | hyperlipidemia | GT | placebo | 900 | 12 | BMI,TG,TC,LDL,HDL,SBP,DBP |
Jain, AK.,1993 [27] | USA | parallel | 20 | 22 | 48 | 55 | hyperlipidemia | GT | placebo | 900 | 12 | TG,TC,LDL,HDL,FBG,SBP,DBP |
Jung, ES.,2014 [28] | Korea | parallel | 28 | 27 | 50.13 | 50.83 | hyperlipidemia | AGE | placebo | 12 | TG,TC,LDL,HDL | |
Kannar, D.,2001 [29] | Australia | parallel | 19 | 22 | 52.6 | 57.4 | hyperlipidemia | GT | placebo | 800 | 12 | TG,TC,LDL,HDL |
Nakasone,Yasushi, 2013 [30] | Japan | parallel | 19 | 21 | 58 | 59 | hypertension | GT | placebo | 188 | 12 | SBP,DBP |
Peleg, A.,2003 [31] | Israel | parallel | 13 | 20 | 52.4 | 54.7 | hyperlipidemia | GT | placebo | 16 | TG,TC,LDL,HDL | |
Riad, Karin,2018 [32] | Australia | parallel | 23 | 26 | 62.8 | 61.9 | hypertension | AGE | placebo | 2400 | 12 | WC,BMI,TG,LDL,HDL,FBG,SBP,DBP |
Sangouni, Abbas A,2020 [33] | Iran | parallel | 45 | 43 | 45.2 | 44.2 | NAFLD | GT | placebo | 1600 | 12 | WC,BMI,TG,TC,LDL,HDL |
Sangouni, Abbas A,2021 [14] | Iran | parallel | 42 | 42 | 46.9 | 44.6 | MetS | GT | placebo | 1600 | 12 | TG,TC,LDL,HDL |
Sharifi, F.,2010 [34] | Iran | parallel | 20 | 20 | 47.9 | 50.5 | MetS | GT | placebo | 1800 | 6 | WC,BMI,TG,TC,HDL,FBG,SBP,DBP |
Simons, LA.,1995 [35] | Australia | crossover | 12 | 17 | 53.6 | 53.6 | hyperlipidemia | GT | placebo | 900 | 12 | TG,TC,LDL,HDL,SBP,DBP |
Superko, HR. 2000 [36] | USA | parallel | 25 | 25 | 53 | 53 | hyperlipidemia | GT | placebo | 900 | 12 | SBP,DBP |
Valls, RM.,2022 [37] | Spain | crossover | 32 | 34 | 53.7 | 52.7 | hyperlipidemia | AGE | placebo | 250 | 6 | SBP,DBP |
Effect of garlic on the components of MetS
Effect of garlic on anthropometric indices
Study | SMD (95% CI) | Weight % |
---|---|---|
Riad, Karin., 2018 [32] | -0.78 (-1.22, -0.33) | 48.82 |
Sangouni, Abbas Ali., 2021 [14] | -0.77 (-1.21, -0.34) | 51.18 |
Sharifi, F., 2010 [34] | (excluded) | 0 |
Overall (I-squared = 0.00, p=0.985) | -0,78 (-1.09, -0.47) | 100 |
Study | SMD (95% CI) | Weight % |
---|---|---|
Higashikawa, Fumiko., 2012 [25] | -0.35 (-0.89, 0.19) | 20.96 |
Isaacsohn, JL., 1998 [26] | -0.08 (-0.69, 0.53) | 20.5 |
Riad, Karin., 2018 [32] | -0.73 (-1.17, -0.29) | 21.48 |
Sangouni, Abbas Ali., 2021 [14] | -0.35 (-0.78, 0.07) | 21.58 |
Sharifi, F., 2010 [34] | -5.00 (-6.28, -3.72) | 15.47 |
Aslani, N., 2016 [21] | (excluded) | 0 |
Overall (I-squared = 92.1%, p=0.000) | 1.10 (-1.99, -0.20) | 100 |
Effect of garlic on blood lipids
Study | SMD (95% CI) | Weight % |
---|---|---|
Adler, A. J., 1997 [20] | -3.15 (-4.44, -1.87) | 5.11 |
Aslani, N., 2016 [21] | -0.54 (-1.07, 0.00) | 7.03 |
Byrne, DJ., 1999 [23] | -0.09 (-0.82, 0.65) | 6.57 |
Gardner, CD., 2001 [24] | -0.13 (-0.70, 0.44) | 6.96 |
Higashikawa, Fumiko., 2012 [25] | -0.33 (-0.87, 0.21) | 7.03 |
Isaacsohn, JL., 1998 [26] | -0.30 (-0.91, 0.32) | 6.86 |
Jain, AK., 1993 [27] | 0.10 (-0.50, 0.71) | 6.88 |
Jung, ES.,2014 [28] | -0.40 (-0.93, 0.14) | 7.04 |
Kannar, D., 2001 [29] | 0.54 (-0.09, 1.17) | 6.84 |
Peleg, A., 2003 [31] | 0.90 (-0.14, 1.94) | 5.77 |
Riad, Karin., 2018 [32] | -0.93 (-1.38, -0.48) | 7.2 |
Sangouni, Abbas Ali., 2021 [14] | -3.19 (-3.83, -2.56) | 6.82 |
Sangouni, Abbas Ali., 2020 [33] | -0.34 (-0.90, 0.22) | 6.98 |
Sharifi, F., 2010 [34] | -2.35 (-3.17, -1.54) | 6.37 |
Simons, LA., 1995 [35] | 0.25 (-0.99, 0.49) | 6.56 |
Overall (I-squared = 89.5%, p=0.000) | -0.66 (-1.17, -0.16) | 100 |
Study | SMD (95% CI) | Weight % |
---|---|---|
Adler, A. J., 1997 [20] | -20.48 (-26.89, -14.08) | 0.42 |
Aslani, N., 2016 [21] | -1.09 (-1.66, -0.52) | 8.61 |
Byrne, DJ., 1999 [23] | -0.48 (-1.23, 0.26) | 7.75 |
Gardner, CD., 2001 [24] | -0.25 (-0.83, 0.32) | 8.59 |
Higashikawa, Fumiko., 2012 [25] | -0.83 (-1.38, -0.27) | 8.66 |
Isaacsohn, JL., 1998 [26] | 0.19 (-0.43, 0.80) | 8.4 |
Jain, AK., 1993 [27] | -0.37 (-0.99, 0.24) | 8.41 |
Jung, ES., 2014 [28] | -0.23 (-0.76, 0.30) | 8.78 |
Kannar, D., 2001 [29] | -0.66 (-1.29, -0.03) | 8.31 |
Peleg, A., 2003 [31] | 0.20 (-0.79, 1.19) | 6.55 |
Sangouni, Abbas Ali., 2021 [14] | -0.93 (-1.37, -0.49) | 9.17 |
Sangouni, Abbas Ali., 2020 [33] | -0.16 (-0.72, 0.39) | 8.67 |
Simons, LA., 1995 [35] | 0.71 (-0.05, 1.47) | 7.67 |
Sharifi, F., 2010 [34] | (excluded) | 0 |
Overall (I-squared = 81.9%, p=0.000) | -0.43 (-0.86, -0.01) | 100 |
Study | SMD (95% CI) | Weight % |
---|---|---|
Adler, A. J., 1997 [20] | -9.33 (-12.34, -6.32) | 1.74 |
Aslani, N., 2016 [21] | -0.99 (-1.55, -0.3) | 8.52 |
Byrne, DJ., 1999 [23] | -0.31 (-1.05, 0.43) | 7.72 |
Gardner, CD., 2001 [24] | -0.18 (-0.76, 0.39) | 8.7 |
Higashikawa, Fumiko., 2012 [25] | -1.11 (-11.68, -0.53) | 8.46 |
Isaacsohn, JL., 1998 [26] | 0.22 (-0.39, 0.84) | 8.3 |
Jain, AK., 1993 [27] | -0.39 (-1.01, 0.22) | 8.3 |
Jung, ES., 2014 [28] | -0.05 (-0.58, 0.48) | 8.66 |
Kannar, D., 2001 [29] | -0.87 (-1.51, -0.23) | 8.16 |
Peleg, A., 2003 [31] | 0.17 (-0.82, 1.16) | 6.57 |
Sangouni, Abbas Ali., 2021 [14] | -0.75 (-1.18, -0.32) | 9.04 |
Sangouni, Abbas Ali., 2020 [33] | 0.07 (-0.48, 0.63) | 8.55 |
Simons, LA., 1995 [35] | 0.99 (0.20, 1.77) | 7.51 |
Overall (I-squared = 83.0%, p=0.000) | -0.44 (-0.88, -0.01) | 100 |
Study | SMD (95% CI) | Weight % |
---|---|---|
Adler, A. J., 1997 [20] | -1.90 (-2.92, -0.88) | 5.18 |
Aslani, N., 2016 [21] | 0.51 (-0.03, 1.05) | 7.1 |
Byrne, DJ., 1999 [23] | -0.37 (-1.12, 0.37) | 6.29 |
Gardner, CD., 2001 [24] | 0.05 (-0.52, 0.62) | 6.97 |
Higashikawa, Fumiko., 2012 [25] | 0.23 (-0.31, 0.76) | 7.11 |
Isaacsohn, JL., 1998 [26] | 0.41 (-0.21, 1.03) | 6.79 |
Jain, AK., 1993 [27] | -0.14 (-0.75, 0.47) | 6.84 |
Jung, ES., 2014 [28] | 0.41 (-0.12, 0.95) | 7.11 |
Kannar, D., 2001 [29] | -0.88 (-1.53, -0.24) | 6.69 |
Peleg, A., 2003 [31] | -0.06 (-1.04, 0.93) | 5.31 |
Riad, Karin., 2018 [32] | 1.34 (0.86, 1.81) | 7.33 |
Sangouni, Abbas Ali., 2021 [14] | 1.04 (0.60, 1.49) | 7.43 |
Sangouni, Abbas Ali., 2020 [33] | -0.04 (-0.59, 0.52) | 7.04 |
Sharifi, F., 2010 [34] | -0.74 (-1.38, -0.10) | 6.7 |
Simons, LA., 1995 [35] | 1.00 (0.21, 1.79) | 6.12 |
Overall (I-squared = 82.8%, p=0.000) | 0.10 (-0.28, 0.48) | 100 |
Effect of garlic on blood pressure
Study | SMD (95% CI) | Weight % |
---|---|---|
Auer, W., 1990 [22] | -0.69 (-1.28, -0.10) | 12.02 |
Isaacsohn, JL., 1998 [26] | 0.22 (-0.39, 0.84) | 11.99 |
Jain, AK., 1993 [27] | 0.15 (-0.46, 0.76) | 12 |
Nakasone, Yasushi, 2013 [30] | -0.69 (-1.41, 0.03) | 11.8 |
Riad, Karin., 2018 [32] | -1.23 (-1.70, -0.77) | 12.2 |
Sharifi, F., 2010 [34] | 5.81 (4.37, 7.26) | 10.04 |
Simons, LA., 1995 [35] | -0.55 (-1.31, 0.20) | 11.73 |
Superko, HR., 2000 [36] | -0.10 (-0.58, 0.38) | 12.18 |
Valls, RM., 2022 [37] | -13.11 (-16.12, -10.10) | 6.04 |
Overall (I-squared = 95.1%, p=0.000) | -0.56 (-1.58, 0.47) | 100 |
Study | SMD (95% CI) | Weight % |
---|---|---|
Auer, W., 1990 [22] | -0.89 (-1.49, -0.29) | 12.28 |
Isaacsohn, JL., 1998 [26] | -0.42 (-1.04, 0.20) | 12.23 |
Jain, AK., 1993 [27] | 0.00 (-0.61,0.61) | 12.27 |
Nakasone, Yasushi, 2013 [30] | -0.96 (-1.70, -0.22) | 11.87 |
Riad, Karin., 2018 [32] | -0.98 (-1.43, -0.52) | 12.65 |
Sharifi, F., 2010 [34] | -2.77 (-3.65, -1.89) | 11.39 |
Simons, LA., 1995 [35] | 0.00 (-0.74, 0.74) | 11.86 |
Superko, HR., 2000 [36] | -0.69 (-1.19, -0.19) | 12.55 |
Valls, RM.,2022 [37] | -18.40 (-22.58, -14.22) | 2.9 |
Overall (I-squared = 92.1%, p=0.000) | -1.33 (-2.14, -0.53) | 100 |
Effect of garlic on FBG
Study | SMD (95% CI) | Weight % |
---|---|---|
Higashikawa, Fumiko., 2012 [25] | 0.00 (-0.53, 0.53) | 20.9 |
Jain, AK., 1993 [27] | -0.10 (-0.71, 0.51) | 20.18 |
Riad, Karin., 2018 [32] | -0.39 (-0.83, 0.04) | 21.83 |
Sharifi, F., 2010 [34] | -1.76 (-2.49, -1.02) | 18.82 |
Simons, LA., 1995 [35] | 0.99 (0.20, 1.77) | 18.28 |
Overall (I-squared = 85.3%, p=0.000) | -0.26 (-0.95, 0.44) | 100 |
Meta-regression and subgroup analysis
TG | TC | LDL | |||||||
Number | Combined Effect Value | Heterogeneity | Number | Combined Effect Value | Heterogeneity | Number | Combined Effect Value | Heterogeneity | |
SMD (95%CI) mmol/L | I2 | SMD (95%CI) mmol/L | I2 | SMD (95%CI) mmol/L | I2 | ||||
overall | 15 | -0.66(-1.17, -0.16)* | 89.50% | 14 | -0.43(-0.86, -0.01)* | 81.90% | 13 | -0.44(-0.88, -0.01)* | 83.00% |
Totals | |||||||||
≥ 50 | 5 | -0.83(-1.08, -0.58)* | 85.90% | 5 | -0.65(-1.02, -0.01)* | 58.90% | 5 | -0.56(-1.02, -0.11)* | 73.40% |
< 50 | 10 | -0.41(-0.62, -0.2)* | 93.70% | 9 | -0.35(-1.07, 0.38) | 85.70% | 8 | -0.46(-1.19, 0.27) | 86.30% |
Age | |||||||||
≥ 50 | 8 | -0.29(-0.5, -0.08)* | 64.80% | 7 | -0.18(-0.55, 0.2) | 58.70% | 7 | -0.15(-0.65, 0.35) | 76.20% |
< 50 | 7 | -1.02(-1.28, -0.77)* | 93.60% | 7 | -0.93(-1.76, -0.09)* | 88.80% | 6 | -0.93(-1.71, -0.15)* | 87.90% |
Dosage | |||||||||
≥ 1000 | 4 | -1.41(-1.7,-1.13)* | 94.40% | 3 | -0.53(-1.32, 0.19) | 78.10% | 2 | -0.36(-1.16, 0.45) | 80.90% |
< 1000 | 8 | -0.17(-0.4, 0.06) | 74.10% | 8 | -0.47(-1.17, 0.22) | 86.60% | 8 | -0.63(-1.36, 0.1) | 88.00% |
Duration | |||||||||
≥ 10w | 13 | -0.51(-0.69, -0.34)* | 89.50% | 13 | -0.37(-0.82, 0.07) | 81.90% | 12 | -0.40(-0.86, 0.07) | |
< 10w | 2 | -1.09(-1.54, -0.64)* | 92.50% | 2 | -1.09(-1.66, -0.52)* | 1 | -0.99(-1.55, -0.43)* | 83.30% | |
Dietary intervention | |||||||||
none | -1.82(-3.66, 0.03) | 91.90% | 3 | -10.22(-29.81, 9.37) | 97.30% | 2 | -4.70(-13.54, 4.14) | 96.90% | |
regular | -0.40(-0.70, -0.11) | 44.30% | 5 | -0.55(-0.90, -0.21) | 44.70% | 5 | -0.54(-0.97, -0.12) | 64.40% | |
advised | -0.46(-1.61, 0.69) | 94.30% | 6 | -0.16(-0.67, 0.35) | 74.40% | 6 | -0.07(-0.62, 0.48) | 77.70% | |
Oral form | |||||||||
row | 1 | -0.54(-1.07, 0.00) | 1 | '-1.09(-1.66, -0.53) | 1 | '-0.99(-1.55, -0.43) | |||
aged | 2 | -0.68(-1.20, -0.17) | 54.30% | 1 | '-0.23(-0.76, 0.30) | 1 | '-0.05(-0.58, 0.48) | ||
produced | 12 | -0.69(-1.36, -0.01) | 91.60% | 13 | '-0.40(-0.90, 0.10) | 83.40% | 11 | '-0.45(-0.97, 0.07) | 84.60% |
HDL | SBP | DBP | |||||||
Number | Combined Effect Value | Heterogeneity | Number | Combined Effect Value | Heterogeneity | Number | Combined Effect Value | Heterogeneity | |
SMD (95%CI) mmol/L | I2 | SMD (95%CI) mmol/L | I2 | SMD (95%CI) mmol/L | I2 | ||||
overall | 15 | 0.1(-0.28, 0.48) | 82.80% | 9 | -0.56(-1.58, 0.47) | 95.1 | 9 | -1.33(-2.14, -0.53)* | 92.10% |
Totals | |||||||||
≥ 50 | 5 | 0.45(0.08, 0.82)* | 61.50% | 2 | -6.52(-19.26, 6.23) | 95.10% | 2 | -9.42(-26.77, 7.94) | 98.50% |
< 50 | 10 | -0.09(-0.66, 0.47) | 86.10% | 7 | 0.27(-0.71, 1.25) | 93.50% | 7 | -0.83(-1.39, -0.26)* | 81.70% |
Age | |||||||||
≥ 50 | 8 | 0.33(-0.16, 0.81) | 80.10% | 6 | -1.51(-2.65, -0.37)* | 94.10% | 6 | -1.52(-2.62, -0.43)* | 93.30% |
< 50 | 7 | -0.16(-0.79, 0.46) | 86.00% | 3 | 1.64(-0.92, 4.20) | 97.00% | 3 | -1.19(-2.61, 0.23) | 92.30% |
Dosage | |||||||||
≥ 1000 | 4 | 0.42(-0.47, 1.31) | 91.40% | 2 | 2.25(-4.65, 9.16) | 98.80% | 2 | -1.23(-2.21, -0.26)* | 92.30% |
< 1000 | 8 | -0.15(-0.64, 0.34) | 76.60% | 7 | -1.08(-2.03, -0.12)* | 92.30% | 7 | -1.83(-3.59, -0.07)* | 92.10% |
Duration | |||||||||
≥ 10w | 13 | 0.14(-0.28, 0.55) | 83.10% | 7 | -0.42(-0.85, 0.01) | 73.10% | 7 | -0.59(-0.90, -0.29)* | 46.30% |
< 10w | 2 | -0.10(-1.32, 1.12) | 88.30% | 2 | -3.60(-22.14, 14.94) | 99.20% | 2 | -10.45(-25.76,4.86) | 98.10% |
Dietary intervention | |||||||||
none | 3 | -0.92(-1.69, -0.16) | 65.00% | 2 | 2.53(-3.85, 8.90) | 98.50% | -1.80(-3.65, 0.04) | 91.70% | |
regular | 6 | 0.42(-0.02, 0.86) | 74.60% | 3 | -3.82(-6.62, -1.03) | 97.40% | -4.33(-7.18, -1.48) | 97.30% | |
advised | 6 | 0.26(-0.36, 0.88) | 82.50% | 4 | -0.23(-0.62, 0.16) | 34.90% | -0.54(-0.90, -0.19) | 20.80% | |
Oral form | |||||||||
row | 1 | 0.51(-0.03, 1.05) | - | - | - | - | - | - | - |
aged | 2 | 0.88(-0.03, 1.79) | 84.60% | 2 | -7.07(-18.71, 4.56) | 98.30% | 2 | -9.56(-26.63, 7.52) | 98.50% |
produced | 12 | -0.07(-0.49, 0.35) | 80.30% | 7 | 0.41(-0.48, 1.29) | 91.90% | 7 | '-0.78(-1.35, -0.22) | 81% |
Sensitivity analysis and publication bias
Quality of evidence
Certainty assessment | № of patients | Effect | Certainty | Importance | |||||||
---|---|---|---|---|---|---|---|---|---|---|---|
№ of | Study design | Risk of bias | Inconsistency | Indirectness | Imprecision | Other considerations | Treatment | Control | Absolute | ||
study | (95% CI) | ||||||||||
TG | Randomized trials | Serious | Not serious | Not serious | Not serious | None | 362 | 339 | SMD 0.66 SD lower | ⨁⨁⨁◯ | important |
15 | (1.17 lower to 0.16 lower) | Moderate | |||||||||
TC | Randomized trials | Serious | Not serious | Not serious | Not serious | None | 320 | 297 | SMD 0.43 SD lower | ⨁⨁⨁◯ | important |
14 | (0.86 lower to 0.01 lower) | Moderate | |||||||||
LDL | Randomized trials | Serious | Not serious | Not serious | Not serious | None | 300 | 277 | SMD 0.44 SD lower | ⨁⨁⨁◯ | important |
13 | (0.88 lower to 0.01 lower) | Moderate | |||||||||
HDL | Randomized trials | Serious | Not serious | Not serious | Not serious | Publication bias strongly suspected | 362 | 339 | SMD 0.1 SD higher | ⨁⨁◯◯ | important |
15 | (0.28 lower to 0.48 higher) | Low | |||||||||
SBP | Randomized trials | Serious | Not serious | Not serious | Not serious | None | 206 | 217 | SMD 0.56 SD lower | ⨁⨁⨁◯ | important |
9 | (1.58 lower to 0.47 higher) | Moderate | |||||||||
DBP | Randomized trials | Serious | Not serious | Not serious | Not serious | None | 206 | 217 | SMD 1.33 SD lower | ⨁⨁⨁◯ | important |
9 | (2.14 lower to 0.53 lower) | Moderate |