Lycopene Supplement and Blood Pressure: An Updated Meta-Analysis of Intervention Trials
Abstract
:1. Introduction
2. Methods
2.1. Search Strategy
2.2. Study Selection
2.3. Data Extraction of Studies
2.4. Quality Assessment of Studies
2.5. Statistical Methods
3. Results
3.1. Literature Selection
3.2. Characteristics of the Included Studies
3.3. Quality Assessment of Selected Studies
3.4. Meta-Analyses Results
3.4.1. Effect of Lycopene Supplement on Blood Pressure
Study, year (reference), region | Study design | Source of lycopene/control | Dosage (mg)/day | Duration | Change of BP treatment vs. control | Participants, m/f, age | Sample size | Other source of lycopene | Assessment of dietary intake |
---|---|---|---|---|---|---|---|---|---|
Thie, 2012 [26], Aberdeen, Scotland | single-blind, RCT | L1: tomato extract capsule (purchased from Holland and Barret) L2: tomato-based foods C: placebo capsule | L1: 10 L2: 10 C: 0 | 16 weeks | SBP: −3.2 vs. −0.3 DBP: −1 vs. −0.7 | men and women; aged 51 years | L: 68 T: 81 C: 76 | no other dietary supplements were allowed | by using seven-day food diaries before and during the run-in period as well as during the intervention |
Kim, 2011 [14], Yonsei, Asia | double-blind, RCT | L: tomato extract capsule (Lyc-O-Mato) C: placebo capsule | L1: 6 L2: 15 C: 0 | 8 weeks | SBP: −3.2 vs. −0.6 | healthy male, smoker or alcohol-drinker, low intake of fruits and vegetables; male, 33.5–34.8 years | L1:41 L2: 37 C: 38 | negligible | by 24-h recall method and semi-quantitative food frequency questionnaire |
Ried, 2009 [15], Australia, Oceania | double-blind, RCT, three-group parallel trial | L: tomato extract capsule (Lyc-O-Mato) C: Placebo capsule | L: 15 C: 0 | 8 weeks | SBP: −2.5 vs. −4.9 DBP: −1.6 vs. −0.5 | prehypertensive adults, with no antihypertensive drugs; 12 m/13 f, 52 ± 12 years | L: 15 C: 10 | negligible | by questionnaires and participants’ daily diary entries |
Paran, 2009 [16], Israel, Asia | double-blind, placebo controlled, two-group crossover trial | L: tomato extract capsule (Lyc-O-Mato) C: placebo capsule | L: 15 C: 0 | 6 weeks | SBP: −13.6 vs. −2.1 DBP: −4.2 vs. −2.1 | mild hypertensives, with one or two antihypertensive drugs; 26 m/24 f, 56 ± 10 years | L: 50 C: 50 | no other dietary supplements were allowed | by dietary query |
Engelhard, 2006 [13], Israel, Asia | single-blind, placebo controlled trial | L: tomato extract capsule (Lyc-O-Mato) C: placebo capsule | L: 15 C: 0 | 8 weeks | SBP: −9.98 vs. −1.05 DBP: −4.06 vs. −1.46 | mild hypertensives, non-smokers with no antihypertensive drugs, 18 m/13 f, 52 ± 21 years | L: 31 C: 31 | no other dietary supplements were allowed | by dietary questionnaire |
Paterson, 2006, [20], U.K, Europe | single-blind, RCT | L: carotenoid-rich canned soups C: carotenoid-poor canned soups | L: 4.5 C: 0 | 4 weeks | SBP: 1 vs. 2 DBP: 1 vs. 2 | healthy adult, 12 m/24 f, 43.5 ± 23.5 years | L: 36 C: 36 | included | by a three-day estimated diet diary |
Study ID | Randomization | Allocation concealment | Blinding | Loss to follow-up | Dietary advice | Compliance | Funding source |
---|---|---|---|---|---|---|---|
Thie, 2012, Scotland [26] | randomized | single-blind | 22/247 | control group was restricted | assessed by measuring serum lycopene concentrations and by analyzing a weekly checklist of tomato-based foods consumed. | funding from the Scottish Government (RESAS). | |
Kim, 2011, Yonsei [14] | randomized | double-blind | 10/126 | maintain their usual lifestyle and dietary habits | assessed using pill counting, food records, and measurement of plasma lycopene levels | National Research Foundation, Korea Health 21 R & D Projects | |
Ried, 2009 Australia [15] | permuted block randomization using the SAS 9.1 software package | sequentially numbered containers | double-blind | 3/39 | maintain their usual diet and physical activity | assessed using participants daily diary entries | RACGP 2006 Pfizer Cardiovascular Research Grant, Australian Government Primary Health Care Research Evaluation Development (PHCRED) Program |
Paran, 2009, Israel [16] | non-randomized | ? | double-blind | 0/50 | no other dietary supplements were allowed and to keep their usual dietary and exercise habits | verified by counting the remaining capsules and by reinforcement at each visit | No funding source provided |
Engelhard, 2006, Israel [13] | non-randomized | ? | single-blind | 3/34 | no other dietary supplements were allowed and to keep their usual dietary habits | by counting the remaining capsules and by reinforcement at each visit | no funding source provided |
Paterson, 2006, UK [20] | block-randomization stratified by age, gender, BMI | ? | single-blind | 0/36 | comprehensive food diaries | assessed by the return of unused products at the end of each intervention period | Unilever Best foods and the University of Reading Research Endowment Trust Fund |
3.4.2. Results of Subgroup Analyses
Group | Total data included | WMD (95% CI) | p | p for heterogeneity | I2, % |
---|---|---|---|---|---|
All | 6 | −4.953 (−8.820, −1.086) | 0.012 | 0.034 | 58.5 |
Baseline of SBP | |||||
<120 mmHg | 3 | −1.441 (−5.320, 2.439) | 0.467 | 0.731 | 0.0 |
>120 mmHg | 3 | −8.034 (−12.411, −3.656) | 0.000 | 0.139 | 49.4 |
Dosage of lycopene | |||||
<12 mg/day | 2 | −1.953 (−6.473, 2.568) | 0.397 | 0.680 | 0.0 |
>12 mg/day | 4 | −6.350 (−11.342, −1.358) | 0.013 | 0.042 | 63.4 |
Duration of intervention | |||||
>8 weeks | 4 | −4.324 (−8.753, 0.105) | 0.056 | 0.100 | 52.1 |
<8 weeks | 2 | −6.320 (−16.609, 3.969) | 0.229 | 0.018 | 82.0 |
Location | |||||
Asia | 3 | −7.661 (−12.480, −2.842) | 0.002 | 0.069 | 62.7 |
Other regions | 3 | −1.368 (−5.573, 2.838) | 0.524 | 0.723 | 0.0 |
Funding | |||||
Support by funding | 4 | −4.481 (−9.821, 0.859) | 0.100 | 0.061 | 59.3 |
No-support by funding | 2 | −5.363 (−13.095, 2.369) | 0.174 | 0.041 | 76.1 |
Group | Total data included | WMD (95% CI) | p | p for heterogeneity | I2, % |
---|---|---|---|---|---|
All | 5 | −0.315 (−0.687, 0.057) | 0.097 | 0.555 | 0 |
Baseline of DBP | |||||
<80 mmHg | 3 | −0.308 (−0.683, 0.068) | 0.108 | 0.927 | 0.0 |
>80 mmHg | 2 | −0.408 (−5.003, 4.188) | 0.862 | 0.095 | 64.1 |
Dosage of lycopene | |||||
<12 mg/day | 2 | −0.305 (−0.681, 0.071) | 0.111 | 0.750 | 0.0 |
>12 mg/day | 3 | −0.629 (−3.746, 2.489) | 0.693 | 0.247 | 28.6 |
Duration of intervention | |||||
>8 weeks | 3 | −0.328 (−0.703, 0.046) | 0.086 | 0.434 | 0.0 |
<8 weeks | 2 | 0.562 (−2.476, 3.600) | 0.717 | 0.314 | 1.4 |
Location | |||||
Asia | 2 | −0.408 (−5.003, 4.188) | 0.862 | 0.095 | 64.1 |
Other regions | 3 | −0.308 (−0.683, 0.068) | 0.108 | 0.927 | 0.0 |
Funding | |||||
Support by funding | 3 | −0.284 (−0.659, 0.092) | 0.139 | 0.530 | 0 |
No-support by funding | 2 | −1.956 (−4.674, 0.763) | 0.159 | 0.572 | 0 |
3.4.3. Sensitivity Analyses
3.4.4. Publication Bias
4. Discussion
5. Conclusions
Author Contributions Statement
Acknowledgements
Conflicts of Interest
References
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Li, X.; Xu, J. Lycopene Supplement and Blood Pressure: An Updated Meta-Analysis of Intervention Trials. Nutrients 2013, 5, 3696-3712. https://doi.org/10.3390/nu5093696
Li X, Xu J. Lycopene Supplement and Blood Pressure: An Updated Meta-Analysis of Intervention Trials. Nutrients. 2013; 5(9):3696-3712. https://doi.org/10.3390/nu5093696
Chicago/Turabian StyleLi, Xinli, and Jiuhong Xu. 2013. "Lycopene Supplement and Blood Pressure: An Updated Meta-Analysis of Intervention Trials" Nutrients 5, no. 9: 3696-3712. https://doi.org/10.3390/nu5093696