Family Practice Advance Access originally published online on October 26, 2008
Family Practice 2008 25(Supplement 1):i60-i66; doi:10.1093/fampra/cmn072
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This article appears in the following Family Practice issue: Creating Supportive Environments for Nutrition Guidance: Towards a Synergy Between Primary Care and Public Health. Proceedings of the Fifth Heelsum International Workshop 10-12 December 2007. [View the issue table of contents]
Diet and nutrition advice from the Cochrane Library: is it useful for the consumers and family physicians?
a Department of Health Information, German Institute for Quality and Efficiency in Health Care (IQWIG), Dillenburger Strasse 27, D-51105 Köln, Germany
b General Practice and Family Medicine, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
c Animal Science Research Institute, Karaj, Iran
d Iranian Cochrane Informal Network
Correspondence to Mona Nasser, Department of Health Information, German Institute for Quality and Efficiency in Health Care, Dillenburger Strasse 27, D-51105 Köln, Germany; Email: mona.nasser{at}iqwig.de
Received 15 May 2008; Revised 18 September 2008; Accepted 19 September 2008.
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Abstract |
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Background. The role of nutrition in public health is well established. This raises the need for reliable and up to date evidence and its ready accessibility for health professionals and consumers.
Objectives. The principal objectives are to evaluate whether nutrition-related Cochrane Systematic Reviews contain clear guidance on nutritional aspects that may be applicable to individual patient care.
Methods. We screened and searched the Cochrane reviews of Issue 3, 2007 of the Cochrane Library. The abstracts were assessed to identify nutrition-relevant reviews which are applicable in the consulting room. All irrelevant studies were excluded and a questionnaire was filled in for each review by the consumers and a Nutrition specialist.
Results. The screening and search of the Cochrane Library Issue 3, 2007 retrieved overall 270 reviews. After excluding the irrelevant results, from the remaining reviews, 17 reviews were about the nutrition and feeding of infants, 44 of the reviews were on diet and nutrition and 78 on nutritional supplementations. From the 38 reviews on nutrition, seven did not have clear translation for the consulting room.
Conclusions. Our study provided an overview of the number of Cochrane reviews on diet and nutrition in Issue 3, 2003 of the Cochrane Library and highlighted the need for more clear and understandable evidence-based information in the field of nutrition.
Keywords. Consumers, diet, family physicians, nutrition, The Cochrane Collaboration.
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Background |
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The role of nutrition and dietary habits in health and medicine is well established and this has got increased attention in media and Internet. However, the available information in the Internet and media for public and consumers has diverse quality and sometimes indeterminate, inconsistent and controversial information. This raises a number of questions and demands that needs to be answered by general physicians and family physicians.1,2 There is a need for reliable evidence on diet and nutrition intervention along with clear, accurate and understandable diet and nutrition advice that could inform the patients for making decisions about their own health status.
The Cochrane Collaboration (http://www.cochrane.org) is an international organizations that is committed to prepare, maintain and promote the accessibility of systematic reviews of the effects of health-care interventions. Despite the considerable number of Cochrane reviews that have been published, the amount of evidence-based guidance on nutrition is still comparatively small and is in part due to the methodological difficulties of performing randomized controlled trials in nutrition. The Diet and Nutrition Subfield of the Cochrane Primary Health Care Field was established in 2004 with its principal aim of providing improved coverage of the field of nutrition within the Cochrane Library.3–5
To increase the relevance and accessibility of evidence to patients and consumers, The Cochrane Collaboration supports the involvement of consumers in Cochrane reviews through the Cochrane Consumer Network (http://www.cochrane.org/consumers) in providing a consumer perspective to Cochrane reviews in the form of plain language summaries (PLSs).
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Objectives |
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The principal objective of this paper is to evaluate whether nutrition-related Cochrane Systematic Reviews contain clear guidance on nutritional aspects that may be applicable to individual patient care in a consulting room of a family practitioner.
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Methods |
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Search
We first undertook a search of the Cochrane Library (http://www.thecochranelibrary.com) Issue 3, 2007 on November 24, 2007 with the search strategy described in Box 1 but then realized that a number of reviews have not been identified by the search and therefore decided to also screen all the titles of Cochrane Library Issue 3, 2007.
Inclusion criteria
Our inclusion criteria were any Cochrane review that evaluated trials which studied the effectiveness of a diet or nutrition supplement intervention that could be implemented in a consulting room of a family physician as judged by one of the authors who is a family physician (JB). Therefore, we excluded interventions e.g. enteral nutrition and those which are implemented in a hospital setting, community or public health setting.
All the titles were independently screened by two individuals (MN/JB) to identify potential titles. Then, we looked at the abstracts of them to identify the reviews that matched our inclusion criteria. All irrelevant studies were excluded (Table 1) and a questionnaire (Box 2) was completed for each review by the two consumers (HJ/KY) and a Nutrition specialist (JB). The responds of the questions were later discussed between the authors (HJ/KY/JB/MN) and were used as a guide to categorize the review titles.
BOX 2. The questionnaire for each review.
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Results |
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The screening and search of the Cochrane Library Issue 3, 2007 retrieved overall 270 Cochrane reviews. We excluded 121 reviews as they were not relevant to nutrition, clearly did not include a diet or nutrition supplement intervention or were withdrawn reviews (one example is the Zinc for common cold review which was included in a previous similar study.6 Then, we excluded 14 further reviews which were not applicable in the consulting room or did not have a direct diet and nutrition supplement intervention (Table 1).
From the remaining studies, 17 of the reviews were about the feeding of newborn and infants (Table 2), 44 of the reviews were on diet and nutrition (Table 3) and 78 on nutrition supplements (Table 4). In some cases, it was difficult to distinguish reviews including nutrition supplement intervention and reviews including dietary advice. One example is the fish oil; in some reviews, only trials that evaluated fish oil supplements were included and in others a change of diet including fish oil was also considered as acceptable.7 In the latter cases, the reviewers may not find primary trials for one or another intervention but we did not exclude the reviews due to this. The other example is laxatives as it sometimes could be given in the form of fibre but we did not included it in this screening. We also did not include reviews on vitamin K, carnitine supplementation, tyrosine supplementation or arginine supplementation as it is usually not given as vitamin supplementation in a diet but mostly as a medical intervention. This could be also true about other vitamins especially in higher doses but we decided to consider all of them in this screening. Moreover, some of diseases might not be a usual case in the family physician practice but we did not excluded reviews based on this reason and confined ourselves whether the intervention can be implemented in a family physician practice or not. Another difficulty was that some of the reviews include a wide range of interventions from pharmaceutical and non-pharmaceutical interventions and it would be difficult to decide whether this might include a nutrition intervention or not. There were also reviews on the effect of caffeine; we included one of the reviews which focused on adults as the consumers believed it could give an indication to the person how many cups of coffee a day could be beneficial or harmful but we excluded the review caffeine versus theophylline for apnoea in preterm infants.
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After selecting the reviews, the authors have discussed whether the PLS can be understood and used in the consulting room. From the 38 reviews on nutrition, in 11 of them, the evaluators did not find the PLS sufficiently clear to be used in a consulting room and additional nutritional amendments were need to be used in a consulting room. This included the following:
- Omega-3 fatty acids for prevention and treatment of cardiovascular disease.
- Interventions for preventing obesity in children.
- Dietary advice for treatment of type 2 diabetes mellitus in adults.
- Dietary salt reduction or exclusion for allergic asthma.
- Dietary interventions for recurrent abdominal pain in childhood.
- Low glycaemic index or low glycaemic load diets for overweight and obesity.
- Interventions for treating obesity in children.
- Diet or exercise, or both, for weight reduction in women after childbirth.
- Dieting to reduce body weight for controlling hypertension in adults.
- Interventions to reduce weight gain in schizophrenia.
- Tartrazine exclusion for allergic asthma.
The reasons were different, in some cases, the reason was that the PLS was limited to one sentence or the type of diet was no clearly described and the consumers could not understand about what kind of diet is discussed in the text.
We also intended to report whether the reviews have found sufficient evidence to reach a conclusion; however, we found it difficult as in some cases, the authors found a number of primary studies with heterogeneous results. In other cases, the authors have been able to answer part of the question e.g. the effect of the intervention in short term but did not find sufficient data to be able to respond to other aspects of the question e.g. the effect of the intervention in long term.
There were different reasons why the reviewers were not able to report a definite conclusion, this included the following:
- No primary trials were identified to address the objective of the review.
- Heterogeneity in the inclusion and exclusion criteria of identified primary trials.
- Heterogeneity in the intervention implemented in the identified primary trials in the review.
- Different outcomes measurements used in the primary trials identified in the review.
- Unexplained heterogeneity in the results of the primary studies.
- Identified primary trials with a short-term follow-up.
- Identified primary trials with a short-term implementation of the intervention.
- Identified primary trials with a small sample size.
- Identified primary trials that were industry funded. There are a number of studies showing that Randomized controlled trial (RCTs) and systematic reviews of heat-to-head comparison of drugs are more likely to report a positive conclusion for the sponsor's product.7–9
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Discussion |
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In a previous study, it was seen that Cochrane reviews only partially cover nutritional aspects6 and in our study, we have found 44 studies which provide diet and nutritional advice for the patients.
The limited evidence available in nutrition is related to the difficulties in conducting randomized controlled trials in nutrition-relevant topics and also the limitations of RCTs in showing the long-term effectiveness of diet and nutrition interventions. Moreover, the trials conducted differ in design, quality and results; this makes it difficult to draw conclusion from them.
Limitations of the study
Identifying reviews relevant to nutrition and diet was challenging. Some of the reviews addressed a broad question of a number of non-pharmaceutical interventions to address a specific disease or health-care problem. This may include nutrition and diet intervention and depending on the primary research available might be reflected in the results or not. Therefore, it was difficult to identify and include them.
This review was done with a limited number of consumers whose first language was not English but were able to read the PLS of the review. Therefore, the judgement of the applicability of the reviews could be different in different groups of people. In this specific group of consumers, a short one sentence explanation of the conclusion in the PLS was considered as insufficient and they have asked for more details to be able to understand why health professionals think that the treatment may or may not work along with the conclusion of the review. In some cases, the reviewers might not have been able to give a clearer definition due to the lack of primary studies to make a conclusion or primary studies with heterogeneous design, quality or inconsistent results. The PLS reflected the uncertainty and the two consumers found it difficult to understand the PLS. This cannot necessarily be judged as a weakness of the reviews and show the difficulties in communicating uncertainties to patients. In the lack of evidence, some strategies used by the reviewers were also judged as useful and clarifying like explaining that the patient has a choice to select the preferred treatment or describing the rational why researchers believe the treatment could be effective or not.
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Conclusion |
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Implication for practice
Our study has shown that there are only a limited number of Cochrane reviews which could help individuals to decide about a healthy diet and most of them do not identify sufficient high-quality RCTs to reach conclusion and provide a clear diet advice for the patients and family practitioners.
Implication for research
- Qualitative studies are needed to understand how patients and consumers interpret the PLS of the Cochrane reviews and whether they acquire the same message that the reviewers intended to convey.
- There is a need for more high-quality systematic reviews and randomized controlled trials especially trials with a longer implementation of the intervention and longer follow-up of the outcomes.
- Social, geographical and cultural differences and their influence on the diet and nutrition intervention should be carefully taken into consideration.10
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Declaration |
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Funding: None.
Ethical approval: None.
Conflicts of interest: None.
Disclaimer: The views expressed in this article represent those of the authors and are not necessarily the views or the official policy of The Cochrane Collaboration or Institute for Quality and Efficiency in Health Care (IQWIG) (www.iqwig.de).
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Acknowledgments |
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MN has run the search and JB and MN have both screened the results. KY, HJ and JB have filled up the questionnaire and MN has been consulted for any disagreements. MN collected the data and wrote the first draft of the article. All the authors participated in the final version of the article.
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Notes |
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Nasser M, van Binsbergen J, Javaheri H and Yassiny K. Diet and nutrition advice from the Cochrane Library: is it useful for the consumers and family physicians? Family Practice 2008; 25: i60–i66.
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References |
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1 Van Dillen SME, Hiddink GJ, Koelen MA, de Graaf C, van Woerkum CMJ. Understanding nutrition communication between health professionals and consumers: development of a model for nutrition awareness based on qualitative consumer research. Am J Clin Nutr (2003) 77(suppl 4):1065S–1072S.
2 Brug J, Oenema A, Kroeze W, Raat H. The internet and nutrition education: challenges and opportunities. Eur J Clin Nutr (2005) 59(suppl 1):S130–S137. discussion S138–S139.[CrossRef][Web of Science][Medline]
3 Becker LA, van Binsbergen JJ. How can a proposed cochrane diet and nutrition field work effectively? Eur J Clin Nutr (2005) 59(suppl 1):S167–S171. discussion S195.[CrossRef][Web of Science][Medline]
4 Lodge M, Becker L, van Binsbergen J, van Weel C, Rosser W. Organisation of a proposed cochrane diet and nutrition field. Eur J Clin Nutr (2005) 59(suppl 1):S162–S166.[CrossRef][Web of Science][Medline]
5 Nasser M, Al Hajeri A. A comparison of handsearching versus embase searching of the archives of Iranian medicine to identify reports of randomized controlled trials. Arch Iran Med (2006) 9:192–195.[Medline]
6 Summerbell CD, Chinnock P, O'Malley C, van Binsbergen JJ. The cochrane library: more systematic reviews on nutrition needed. Eur J Clin Nutr (2005) 59(suppl 1):S172–S178.[CrossRef][Web of Science][Medline]
7 Bero L, Oostvogel F, Bacchetti P, Lee K. Factors associated with findings of published trials of drug-drug comparisons: why some statins appear more efficacious than others. PLoS Med (2007) 4:e184.[CrossRef][Medline]
8 Yank V, Rennie D, Bero LA. Financial ties and concordance between results and conclusions in meta-analyses: retrospective cohort study. BMJ (2007) 335:1202–1205.
9 Jørgensen AW, Hilden J, Gøtzsche PC. Cochrane reviews compared with industry supported meta-analyses and other meta-analyses of the same drugs: systematic review. BMJ (2006) 333:782–786.
10 Summerbell CD, Ashton V, Campbell KJ, Edmunds L, Kelly S, Waters E. Interventions for treating obesity in children. Cochrane Database Syst Rev (2003) issue 3 Art. No.: CD001872. DOI: 10.1002/14651858.CD001872.
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