- Adriana Buitrago-Lopez, visiting research assistant123,
- Jean Sanderson, research associate1,
- Laura Johnson, research associate1,
- Samantha Warnakula, PhD student1,
- Angela Wood, university lecturer in biostatistics1,
- Emanuele Di Angelantonio, university lecturer in medical screening1,
- Oscar H Franco, clinical lecturer in public health1
- 1Department of Public Health and Primary Care, Cardiovascular Epidemiology Unit, University of Cambridge, Strangeways Research Laboratory, Cambridge CB1 8RN, UK
- 2Fundacion Universitaria de Ciencias de la Salud, Hospital de San Jose, Bogota, Colombia
- 3Pontificia Universidad Javeriana, Bogota, Colombia
- Correspondence to: O H Franco
- Accepted 23 May 2011
Objective To evaluate the association of chocolate consumption with the risk of developing cardiometabolic disorders.
Design Systematic review and meta-analysis of randomised controlled trials and observational studies.
Data sources Medline, Embase, Cochrane Library, PubMed, CINAHL, IPA, Web of Science, Scopus, Pascal, reference lists of relevant studies to October 2010, and email contact with authors.
Study selection Randomised trials and cohort, case-control, and cross sectional studies carried out in human adults, in which the association between chocolate consumption and the risk of outcomes related to cardiometabolic disorders were reported.
Data extraction Data were extracted by two independent investigators, and a consensus was reached with the involvement of a third. The primary outcome was cardiometabolic disorders, including cardiovascular disease (coronary heart disease and stroke), diabetes, and metabolic syndrome. A meta-analysis assessed the risk of developing cardiometabolic disorders by comparing the highest and lowest level of chocolate consumption.
Results From 4576 references seven studies met the inclusion criteria (including 114 009 participants). None of the studies was a randomised trial, six were cohort studies, and one a cross sectional study. Large variation was observed between these seven studies for measurement of chocolate consumption, methods, and outcomes evaluated. Five of the seven studies reported a beneficial association between higher levels of chocolate consumption and the risk of cardiometabolic disorders. The highest levels of chocolate consumption were associated with a 37% reduction in cardiovascular disease (relative risk 0.63 (95% confidence interval 0.44 to 0.90)) and a 29% reduction in stroke compared with the lowest levels.
Conclusions Based on observational evidence, levels of chocolate consumption seem to be associated with a substantial reduction in the risk of cardiometabolic disorders. Further experimental studies are required to confirm a potentially beneficial effect of chocolate consumption.
We thank Isla Kuhn (medical library, University of Cambridge) for her advice and support with the search strategy, Nadeem Sarwar for his valuable comments, and Jorge Daza (Fundacion Universitaria de Ciencias de la Salud, Hospital de San Jose Library) for his constant support.
Contributors: OHF conceived the study. AB-L, OHF, and EDA did the analyses. AB-L, JS, LJ, SW, AW, and OHF searched the literature and extracted the data. AB-L and OHF wrote the manuscript. JS, LJ, SW, AW, and EDA contributed to the initial revision of the manuscript. LJ contributed to the critical revision of the manuscript before publication. OHF is the guarantor.
Funding: This study received no specific funding.
Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare: no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.
Ethical approval: Not required.
Data sharing: No additional data available.
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