EXTERNAL SCIENTIFIC REPORT

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1 EFSA supporting publication 2015:EN-590 EXTERNAL SCIENTIFIC REPORT Extensive literature search and review as preparatory work for the evaluation of the essential composition of total diet replacement products for weight control 1 N. Terzikhan MSc, EL Doets PhD, M Vonk Noordegraaf-Schouten PhD Pallas health research and consultancy, Conradstraat 18, 3013 AP, Rotterdam, the Netherlands ABSTRACT For this review a comprehensive literature search was carried out to identify human intervention studies, which investigated the effect of differences in composition of low and very low calorie diets on adverse metabolic effects. We identified 2653 papers in PubMed, of which nine papers met our inclusion criteria. These included publications reported on different types of low calorie diets, including ketogenic and nonketogenic diets (n = 4), diets differing in content of macronutrients (proteins, fat and carbohydrates) and energy value (n = 2), a diet supplemented with pyruvate (n = 1) and diets supplemented with fatty acids (medium-chain triglycerides (n = 1) and omega-3 fatty acids (n = 1)). Only four of the nine publications investigated comparable diets. The main adverse health outcomes in the studies included ketosis (n = 7), metabolic acidosis (n = 1), muscle loss/protein sparing (n = 6), mood and cognition (n = 2), gallstone formation (n = 1), organ functioning (n = 2) and complaints (n = 3), and essential fatty acid status (n = 1). The evidence summarized in this review shows that a very low calorie ketogenic diet as compared to a very low calorie nonketogenic diet resulted in higher concentrations of ketone bodies. In one study mild acidosis was reported in the ketogenic diet group. In addition, in three studies, very low calorie nonketogenic diets showed to be superior to ketogenic diets in protein sparing during a period of 4 weeks. Gallstone formation was reported in one study comparing a low calorie diet with a very low calorie diet, and liver function was tested in three single studies on very low calorie diets, but results were inconclusive. Other frequent complaints that were mentioned in the studies included constipation, borborygmus, diarrhoea, dizziness, dry skin, cold intolerance and hair loss, but no statistical significant differences in occurrence were observed between intervention and control groups. Pallas health research and consultancy, 2015 KEY WORDS low calorie diet, very low calorie diet, meal replacement, adverse metabolic effects DISCLAIMER The present document has been produced and adopted by the bodies identified above as author(s). This task has been carried out exclusively by the author(s) in the context of a contract between the European Food Safety Authority and the author(s), awarded following a tender procedure. The present document is published complying with the transparency principle to which the Authority is subject. It may not be considered as an output adopted by the Authority. The European food Safety Authority reserves its rights, view and position as regards the issues addressed and the conclusions reached in the present document, without prejudice to the 1 Question No EFSA-Q Any enquiries related to this output should be addressed to nda@efsa.europa.eu Suggested citation: Terzikhan N., Doets E.L. and Vonk Noordegraaf-Schouten M, Extensive literature search and review as preparatory work for the evaluation of the essential composition of total diet replacement products for weight control. EFSA supporting publication 2015:EN-590, 94 pp. Available online: European Food Safety Authority, 2015

2 SUMMARY This review was carried out as preparatory work for EFSA s advice on the essential composition of total diet replacement products, RC/EFSA/NUTRI/2013/04. Obesity (BMI >30 kg/m2) is a major public health problem in Europe. Dietary intake is a critical determinant of body weight. People s energy intake must exceed their energy expenditure over a prolonged period of time for them to become obese (WHO 2007). This suggests that an increase in energy expenditure and decrease in energy intake would result in weight loss. Very low and low calorie diets (VLCD and LCD) in the form of meal replacement products are frequently used to reduce energy intake and thereby induce rapid weight loss, while preserving lean body mass. The objective of this review was to perform a comprehensive literature search and to summarise available data on human intervention studies which investigated the effect of differences in composition of VLCD and LCD on adverse metabolic effects in otherwise healthy overweight or obese populations. These include studies that investigate nutrient status, specifically iron, iodine and essential fatty acids; losses of lean body mass; ketosis; physical or cognitive performance; heart, liver and kidney function; and hydration. Methods In November 2013, a literature search was performed in PubMed to identify peer-reviewed publications on human studies published in English since 1990 that were relevant for the objective. Relevant publications were systematically selected for the review following a three-step selection process: 1) screening of titles and abstracts of all references identified with the search (TiAb), 2) screening full-text publications of references included during step 1; 3) further scrutiny of full text publications during data extraction. For each objective, inclusion was based on predefined criteria for study design, characteristics, population, topic, intake and outcomes. Results In total, 2653 unique hits were identified in PubMed. Based on title and abstract, 342 original research publications were selected for full text assessment. Of these publications, 329 were excluded, 9 randomized controlled trials were included in the evidence tables and 4 publications could not be retrieved. Main reasons for exclusion of research publications were: no systematic literature review, no meal replacement products, partial meal replacement, positive health outcomes (e.g. weight loss, improved blood lipids profile) or outcomes not directly related to health (e.g. mitochondrial oxidation, genotype depended response, endothelial function etc.) Different types of VLCD and LCD regimens were found in the publications, including ketogenic and nonketogenic diets, diets differing in content of macronutrients (proteins, fat and carbohydrates) and caloric value, a diet supplemented with pyruvate, and diets supplemented with fatty acids (Medium Chain Triglyceride; MCT and n-3 PUFA). Only four of the nine publications investigated comparable diets. The health outcomes included ketosis (n = 7), metabolic acidosis (n = 1), muscle loss/protein sparing (n = 6), mood and cognition (n = 2), gallstone formation (n = 1), organ functioning (n = 2) and complaints (n = 3), and essential fatty acid status (n = 1). EFSA supporting publication 2015:EN The present document has been produced and adopted by the bodies identified above as author(s). This task has been carried out exclusively by the author(s) in the context of a contract between the European Food Safety Authority and the author(s), awarded following a tender procedure. The present document is published complying with the transparency principle to which the Authority is subject. It may not be considered as an output adopted by the Authority. The European Food Safety Authority reserves its rights, view and position as regards the issues addressed and the conclusions reached in the present document, without prejudice to the

3 The 9 included RCT s were extracted into the EURRECA database. The quality of each publication was assessed. Publications were divided into two groups according to their risk of bias: moderate risk of bias (n = 6) and high risk of bias (n = 3). Conclusion The evidence summarized in this review shows that a very low calorie ketogenic diet as compared to a very low calorie nonketogenic diet resulted in higher concentrations of ketone bodies. In one study mild acidosis was reported in the ketogenic diet group. In addition, in three studies, very low calorie nonketogenic diets showed to be superior to ketogenic diets in protein sparing during a period of 4 weeks. Gallstone formation was reported in one study comparing a low calorie diet with a very low calorie diet, and liver function was tested in three single studies on very low calorie diets, but results were inconclusive. Other frequent complaints that were mentioned in the studies included constipation, borborygmus, diarrhoea, dizziness, dry skin, cold intolerance and hair loss, but no statistical significant differences in occurrence were observed between intervention and control groups. EFSA supporting publication 2015:EN The present document has been produced and adopted by the bodies identified above as author(s). This task has been carried out exclusively by the author(s) in the context of a contract between the European Food Safety Authority and the author(s), awarded following a tender procedure. The present document is published complying with the transparency principle to which the Authority is subject. It may not be considered as an output adopted by the Authority. The European Food Safety Authority reserves its rights, view and position as regards the issues addressed and the conclusions reached in the present document, without prejudice to the

4 TABLE OF CONTENTS Abstract... 1 Summary... 2 Table of contents... 4 Background... 5 Objectives... 5 Terms of reference Introduction Overweight and obesity Very low calorie diets Low calorie diets Materials and Methods Identification of relevant data Data sources PubMed Search limits Hand search Selection phase Data extraction Validity assessment Results Quality and risk of bias assessment of studies Ketosis Ketogenic diet and ketosis Diets enriched with fatty acids and ketosis Metabolic acidosis Protein sparing Ketogenic diet and protein sparing Diet enriched with fatty acids and protein sparing VLCD supplemented with pyruvate and protein sparing Cognitive function and mood Other adverse effects Gallstone formation Organ functioning and complaints Status of essential fatty acids Discussion Ketogenic diets and ketosis Protein sparing Other adverse effects Confounding Quality Conclusion References Appendices Appendix A: Search Strings Appendix B: Inclusion and exclusion criteria Appendix C: Exclusion list PubMed Appendix D: Not available list pubmed Abbreviations EFSA supporting publication 2015:EN The present document has been produced and adopted by the bodies identified above as author(s). This task has been carried out exclusively by the author(s) in the context of a contract between the European Food Safety Authority and the author(s), awarded following a tender procedure. The present document is published complying with the transparency principle to which the Authority is subject. It may not be considered as an output adopted by the Authority. The European Food Safety Authority reserves its rights, view and position as regards the issues addressed and the conclusions reached in the present document, without prejudice to the

5 BACKGROUND In the framework of revision of Union law on dietetic products, the European Food Safety Authority (EFSA) will receive a mandate from the European Commission to provide advice on the essential composition of total diet replacement products for weight control, including low and very low calorie diets (LCD and VLCD). In order to accomplish the task, Pallas was awarded the preparatory work to conduct a comprehensive literature search with respect to metabolic effects of different compositions of such diet replacement products. OBJECTIVES The overall objective of the specific contract is to perform a comprehensive literature search and to provide EFSA with an evidence report summarising the data retrieved related to: I. Human intervention studies which investigated the effect of differences in composition of VLCDs on adverse metabolic effects. II. Human intervention studies which investigated the effect of differences in composition of LCDs on adverse metabolic effects. The review focuses on the effect of composition of LCD and VLCD products or regimens on adverse metabolic effects in otherwise healthy overweight or obese populations, related to: nutrient status, specifically to iron, iodine and essential fatty acids losses of lean body mass ketosis physical or cognitive performance heart, liver and kidney function hydration TERMS OF REFERENCE Literature search and review related to specific preparatory work This contract was awarded by EFSA to: Pallas health research and consultancy, Rotterdam, the Netherlands. Contractor: Mw. Dr. J.H. Van den Bosch, Managing Director. Contract title: Extensive literature search and review as preparatory work for the evaluation of the essential composition of total diet replacement products for weight control Contract number: RC/EFSA/NUTRI/2013/04 EFSA supporting publication 2015:EN The present document has been produced and adopted by the bodies identified above as author(s). This task has been carried out exclusively by the author(s) in the context of a contract between the European Food Safety Authority and the author(s), awarded following a tender procedure. The present document is published complying with the transparency principle to which the Authority is subject. It may not be considered as an output adopted by the Authority. The European Food Safety Authority reserves its rights, view and position as regards the issues addressed and the conclusions reached in the present document, without prejudice to the

6 1. Introduction 1.1. Overweight and obesity Obesity (BMI > 30 kg/m 2 ) is a major public health problem in Europe. Substantial evidence shows that overweight and obesity are major causes of co-morbidities, including type II diabetes, cardiovascular diseases, various cancers and other health problems. These co-morbidities can lead to further morbidity and mortality. Estimates from the WHO European Region show that more than 1 million deaths and 12 million life-years of ill health every year can be attributed to obesity and overweight (WHO 2007). The prevalence of overweight in Europe differs between countries. Based on national and international surveys from the last 15 years, WHO estimates that in the European Union % of men and % of females were overweight (BMI>25 kg/m 2 ). The prevalence of obesity ranged from 5.4% to 22.8 % among men and from 7.1% to 35.6 % among women. Dietary intake is a critical determinant of body weight. People s energy intake must exceed their energy expenditure over a prolonged period of time for them to become obese. This suggests that an increase in energy expenditure and decrease in energy intake would results in weight loss. LCDs and VLCDs in the form of meal replacements are frequently used to reduce energy intake and thereby induce rapid weight loss, while preserving lean body mass (Tsai 2006) Very low calorie diets VLCD is a special type of diet that provides less than 800 kcal per day and replaces all meals with prepared formulas, usually liquid shakes, soups or bars. The formula foods used in a very low calorie diet contain adequate amounts of vitamins, minerals, trace elements, fatty acids and proteins, whereas carbohydrate may be entirely absent, or substituted for a portion of the protein. The diets are designed to produce rapid weight loss while preserving lean body mass. This is accomplished by providing large amounts of dietary protein, 70 to 100 g/day or 0.8 to 1.5 g protein/kg ideal body weight (Tsai 2006). The composition of formula foods used in VLCD are regulated by CODEX STAN (CODEX-Alimentarius 1995) Low calorie diets LCD provides between 800 and 1200 kcal per day with formula foods as a replacement for all or part of the total daily diet. A formula food presented as a replacement for one or more meals of the daily diet shall provide not less than 200 kcal (835 kj) and not more than 400 kcal (1670 kj) per meal. Formula foods used as diet replacement for LCDs are regulated by CODEX STAN (CODEX-Alimentarius. 1991). EFSA supporting publication 2015:EN The present document has been produced and adopted by the bodies identified above as author(s). This task has been carried out exclusively by the author(s) in the context of a contract between the European Food Safety Authority and the author(s), awarded following a tender procedure. The present document is published complying with the transparency principle to which the Authority is subject. It may not be considered as an output adopted by the Authority. The European Food Safety Authority reserves its rights, view and position as regards the issues addressed and the conclusions reached in the present document, without prejudice to the

7 2. Materials and Methods Total diet replacement products for weight control In order to meet the objectives as outlined above, the consortium consisting of Pallas and the Division of Human Nutrition of Wageningen University and Research centre (Wageningen UR) performed a comprehensive review of the literature on the intake of diet replacement products and adverse metabolic outcomes. A comprehensive review is a method to collect, critically appraise and summarize the best available evidence in a transparent and systematic way, using generally accepted evidence-based principles. Extended information on methodology of the review was specified in a protocol. This was discussed and agreed with EFSA. The main review steps are outlined below Identification of relevant data Data sources According to the defined scope of the systematic review and in consultation with EFSA, PubMed was identified being the appropriate database for identifying relevant literature PubMed Three search strings were composed: A: Terms for diet replacements products and weight control B: Terms for VLCDs and LCDs C: General terms for composition The search strings were combined as ((A OR B) AND C) AND general strings to identify human studies, specific methodological designs or study types (Appendix A). To minimize the risk of missing relevant articles on this subject, no search string for specific adverse metabolic effects was added. Articles on relevant metabolic effects will be selected during the literature selection procedure (see section 2.2). We performed one search for objective I and II combined, since the objectives only differ with respect to the energy content of the diets. Articles pertinent for objective I or objective II were selected during the literature selection procedure (see section 2.2) Search limits The following limits were used for the search: Languages: English (PubMed limit) Human studies (search string in Appendix A) Study designs: systematic reviews/meta-analyses, RCTs and controlled intervention studies (search strings in Appendix A) The PubMed limits human studies and publication types were not used, as previous experiences have indicated that these limits may exclude relevant articles. This has been confirmed by information specialists. To exclude animal studies and non-relevant publication types such as editorials and caseseries, specific search strings for human studies and study designs was applied (see Appendix A). Animal studies or non-pertinent study designs that still resulted from the PubMed search were excluded during the first selection step (see Section 2.2). EFSA supporting publication 2015:EN The present document has been produced and adopted by the bodies identified above as author(s). This task has been carried out exclusively by the author(s) in the context of a contract between the European Food Safety Authority and the author(s), awarded following a tender procedure. The present document is published complying with the transparency principle to which the Authority is subject. It may not be considered as an output adopted by the Authority. The European Food Safety Authority reserves its rights, view and position as regards the issues addressed and the conclusions reached in the present document, without prejudice to the

8 Hand search Total diet replacement products for weight control The reference lists of relevant review articles, reports and included publications were checked for further potentially relevant articles possibly missed by the search in above mentioned bibliographic databases Selection phase Key references from the peer-reviewed literature search were selected by a three-step selection procedure, using predefined inclusion and exclusion criteria. The complete list of criteria used is specified in Appendix B. Selection steps were: Screening of title and abstract: during this selection step, articles that appeared to contain information relevant to the research objective were selected for full text assessment. Selection based on title and abstract was performed by two independent reviewers from Pallas. The first 10% of the references were screened in duplicate. The results were compared and discussed before the remaining references were assessed. Screening of full articles: in this step the full text articles were assessed. These articles were either included, or excluded when it turned out that the article did not contain relevant information. The reasons for exclusion of full text publications were documented per article and summarised in the exclusion table (Appendix C). Critical appraisal of full text articles was performed by one independent reviewer from Pallas. A random sample of 10% of the articles was screened in duplicate. The results were compared and discussed early in the screening process. In addition to the eligibility criteria listed in the protocol, it was decided that only publications reporting on diets with total meal replacement in relation to adverse metabolic outcomes were included in this review. Publications reporting on metabolic effects of diets that consisted both of meal replacement products and regular foods were excluded. As agreed with EFSA, the following types of studies were flagged in the exclusion list (n = 19) (see Appendix C): 1- Studies that met the inclusion criteria of this review (e.g. with an applicable health outcome) but partial meal replacement intervention. 2- Studies that met the inclusion criteria of this review (e.g. with an applicable comparison between meal replacement diets) but with an improvement of health outcome; especially for heart function health outcomes. The complete process of selection and in- and exclusion of articles was recorded in Excel-formats and an Endnote library by one of the researchers. This way, a clear overview on all selection steps was maintained at all phases Data extraction Evidence from the included publications was extracted into the Access database that has been provided by EURRECA. Depending on the study design, information was inserted into different fields. Data extraction included the following: Study characteristics: publication references, study name, funder of the study, country of origin, characteristics of the study population (e.g. gender, age and ethnicity). EFSA supporting publication 2015:EN The present document has been produced and adopted by the bodies identified above as author(s). This task has been carried out exclusively by the author(s) in the context of a contract between the European Food Safety Authority and the author(s), awarded following a tender procedure. The present document is published complying with the transparency principle to which the Authority is subject. It may not be considered as an output adopted by the Authority. The European Food Safety Authority reserves its rights, view and position as regards the issues addressed and the conclusions reached in the present document, without prejudice to the

9 design and groups description: number of participants per group, intervention duration, drop outs and reasons of drop outs. Status measure: description of analytical method to assess status measure, information about reproducibility. Outcome measures: description of outcome measure(s) and case definition, information about reproducibility. Study results: type of analyses used to compare health effects of different types of dietary interventions, summary of key results in text, and extended results. Validity assessment: randomisation procedures (RCT s), drop outs, representativeness of study population, power calculation, evaluation of misreporting, funders of the study, identification of potential confounders, measurement errors, completeness of reporting of exposure and outcome data, sources of bias described by the author. Evidence tables were exported from the database and reviewed by a senior researcher. Some included publications reported on a large range of specific secondary outcomes, e.g. plasma substrate and hormone concentrations including thyroid hormone levels and insulin. In case of doubt, EFSA was consulted to decide which health outcomes were extracted in the evidence tables Validity assessment During the data extraction phase, publications were graded according to study methodology, using the criteria from EURRECA bias assessment. Studies were classified as high, moderate, or low risk of bias based on criteria specific for each study design. Criteria for validity assessment of RCTs included into the EURRECA database were, amongst others randomisation, allocation method, blinding, loss to follow up and similarity of intervention and control group at baseline, and funding. In case an RCT had at most one important risk of bias (e.g. blinding or funding inadequate), but other areas were all adequate, the risk of bias was categorized as moderate and when more than one important risk of bias was present, the risk of bias was evaluated as high. 3. Results For objectives I and II, a total of 2653 unique hits were identified in PubMed. Based on title and abstract, 342 original research publications were selected for full text assessment. Of these publications, 9 RCTs were included in the evidence tables, 329 publications were excluded and 4 were not found (see Appendix D). Main reasons for exclusion of research publications were: no systematic literature review, no meal replacement, partial meal replacement, positive health outcomes (e.g. weight loss, improved blood lipids profile) or outcomes not directly related to health (e.g. mitochondrial oxidation, genotype depended response, endothelial function et cetera). The flow chart in Figure 1 presents an overview of the selection procedure in the PubMed search. A list of reasons for excluding references during the full text assessment can be found in Appendix C. An overview of the publications included in this report is provided in Table 1. Detailed results of the included publications are described in evidence tables at the end of this report (Table 4; Summary of the included publications, Table 5 Results of the included publications, and Table 6 The quality of the included publications). In total, eight publications investigated the effect of differences in composition of VLCDs on adverse metabolic effects (objective I) and two publications investigated the effect of differences in composition of LCDs on human adverse metabolic effects (objective II) (See Table 1). EFSA supporting publication 2015:EN The present document has been produced and adopted by the bodies identified above as author(s). This task has been carried out exclusively by the author(s) in the context of a contract between the European Food Safety Authority and the author(s), awarded following a tender procedure. The present document is published complying with the transparency principle to which the Authority is subject. It may not be considered as an output adopted by the Authority. The European Food Safety Authority reserves its rights, view and position as regards the issues addressed and the conclusions reached in the present document, without prejudice to the

10 Table 1: Overview of publications included in the evidence tables and review tables. Forster et al Kunesova et al Author Krotkiewski et al Wing et al Vazquez et al 1992 & 1994 Vazquez et al 1995 Stanko et al Krotkiewski et al Vazquez et al 1992 & 1994 Vazquez et al 1998 Forster et al Wing et al Forster et al Forster et al Vazquez et al 1992, 1994 & 1995 Stanko et al and control diets differ in a Caloric value, protein, carbohydrates and total fat n-3 PUFA b Triglycerides Carbohydrates and total fat Carbohydrates and total fat Protein and carbohydrates Pyruvate Triglycerides Carbohydrates and total fat Protein and carbohydrates Protein, carbohydrates and total fat Carbohydrates and total fat Protein, carbohydrates and total fat Protein, carbohydrates and total fat Protein and total fat Pyruvate Health-related outcome Ketosis Nitrogen balance/ FFM c / Protein sparing Cognitive function and mood Symptoms (complaints) Gebhard et al total Fat Gall bladder emptying Kunesova et al n-3 PUFA b Essential fatty acids composition Vazquez et al 1992 Carbohydrates and total fat Metabolic acidosis Vazquez et al 1992 & 1994 Carbohydrates and total fat Organ function Stanko et al Pyruvate a In all studies VLCDs were consumed providing between 240 and 615 kcal/day, except for Stanko et al (LCD 1015 kcal/day) and Gebhard et al (VLCD 590 kcal/day vs LCD 900 kcal/day). b PUFA: Poly Unsaturated Fatty Acids. c Fat Free Mass EFSA supporting publication 2015:EN The present document has been produced and adopted by the bodies identified above as author(s). This task has been carried out exclusively by the author(s) in the context of a contract between the European Food Safety Authority and the author(s), awarded following a tender procedure. The present document is published complying with the transparency principle to which the Authority is subject. It may not be considered as an output adopted by the Authority. The European Food Safety Authority reserves its rights, view and position as regards the issues addressed and the conclusions reached in the present document, without prejudice to the

11 2651 unique hits Selection step 1: Title and abstract 342 unique articles screened full text Selection step 2: Full text Included; n = 9 Excluded; n = 329 Not found n = 4 Figure 1: Selection procedure of publications based on number of hits in PubMed EFSA supporting publication 2015:EN The present document has been produced and adopted by the bodies identified above as author(s). This task has been carried out exclusively by the author(s) in the context of a contract between the European Food Safety Authority and the author(s), awarded following a tender procedure. The present document is published complying with the transparency principle to which the Authority is subject. It may not be considered as an output adopted by the Authority. The European Food Safety Authority reserves its rights, view and position as regards the issues addressed and the conclusions reached in the present document, without prejudice to the

12 3.1. Quality and risk of bias assessment For each publication included in our review the risk of bias was evaluated. Out of 9 included publication, 6 were evaluated as having moderate risk of bias (Stanko, Tietze et al. 1992; Vazquez and Adibi 1992; Vazquez and Kazi 1994; Vazquez, Kazi et al. 1995; Krotkiewski 2001; Kunesova, Braunerova et al. 2006) and 3 with high risk of bias (Foster, Wadden et al. 1992; Wing, Vazquez et al. 1995; Gebhard, Prigge et al. 1996). None of the RCT s was evaluated as having a low risk of bias, because none of the included publications reported on the power calculation and the method of sequence generation, most publications only reported that subjects were randomly assigned to receive the diet. In Table 2, key reasons for categorizing RCT s as moderate or high risk of bias are presented. Table 6 describes detailed information about quality aspects of the included publications. Table 2: Key reasons for moderate and high risk of bias of RCT s included in the review. Moderate risk of bias Sequence generation unclear Krotkiewki 2001,Kunesova 2006, Stanko 1992, Vazquez 1992, Vazquez 1994, Vazquez 1995 Sequence allocation unclear Krotkiewki 2001, Kunesova 2006, Stanko 1992, Vazquez 1992, Vazquez 1994, Vazquez Other potential threats to validity are present b Krotkiewki 2001,Kunesova 2006, Stanko 1992, Vazquez 1992, Vazquez 1994, Vazquez 1995 High risk of bias a Sequence generation unclear Foster 1992, Gebhard 1996, Wing Sequence allocation unclear Wing Funding from profit organisation Foster 1992, Gebhard 1996 Similarity intervention and control group inadequate or unclear Wing 1995 Other potential threats to validity are present b Foster 1992, Gebhard 1996, Wing a For publications with a risk of bias evaluate as high, multiple reasons are indicated. b Other potential treats to validity include: no power calculation, insufficient power, differences in composition of nutrients not addressed in the study, intervention duration too short according to authors 3.2. of studies In this section, the included studies are described according to adverse health outcomes in the following order: Ketosis, metabolic acidosis, protein sparing, cognitive function, and other health outcomes (including gallstone formation, organ function and complaints). A paper may be discussed more than once if it describes two or more of the health outcomes of interest Ketosis Ketosis is a metabolic state where ketone bodies and free fatty acids replace glucose as the primary fuel of the body in most tissues. It indicates a shift from a carbohydrates based metabolism to fat and ketone based metabolism. These changes tend to minimize body s protein losses during periods of caloric deprivation and may thereby prevent the loss of fat free mass (FFM). Under normal conditions, ketone bodies (ß-hydroxybutyrate, acetoacetate and acetone) are present in the blood in small amounts (~ 0.1 mmol/dl). A ketone concentration of above the 0.2 mmol/dl is clinically defined as ketosis (McDonald 1998). EFSA supporting publication 2015:EN The present document has been produced and adopted by the bodies identified above as author(s). This task has been carried out exclusively by the author(s) in the context of a contract between the European Food Safety Authority and the author(s), awarded following a tender procedure. The present document is published complying with the transparency principle to which the Authority is subject. It may not be considered as an output adopted by the Authority. The European Food Safety Authority reserves its rights, view and position as regards the issues addressed and the conclusions reached in the present document, without prejudice to the

13 Ketogenic diet and ketosis Total diet replacement products for weight control A ketogenic diet can be defined as a diet containing less than 100 or 50 grams of carbohydrates per day (inconsistent definitions) and a relative increase in the proportions of protein and fats (McDonald 1998; Paoli, Rubini et al. 2013). The brain needs daily about 100 grams of glucose per day, if insufficient carbohydrates are consumed to provide this amount of glucose, the liver will start producing ketone bodies that can be used by the brain as an alternative to glucose and finally ketosis can occur (McDonald 1998; Paoli, Rubini et al. 2013). The safety of ketogenic diet is therefore controversial. In this review, seven studies measured ketosis during the intervention (Foster, Wadden et al. 1992; Vazquez and Adibi 1992; Vazquez and Kazi 1994; Vazquez, Kazi et al. 1995; Wing, Vazquez et al. 1995; Krotkiewski 2001; Kunesova, Braunerova et al. 2006). Most studies used plasma and/or urine concentrations of ß-hydroxybutyrate as an indicator for ketosis, but serum concentrations of acetone and acetoacetate were measured in some studies as well. ß-hydroxbutyrate Four comparable studies from the USA (Vazquez and Adibi 1992; Vazquez and Kazi 1994; Vazquez, Kazi et al. 1995; Wing, Vazquez et al. 1995), with moderate risk of bias, investigated the effect of ketogenic diets on ketosis using isocaloric isonitrogenous nonketogenic diets as a control. Table 3 summarizes the difference in diet composition, number of subjects, baseline- and end-concentrations of ß-hydroxybutyrate in plasma or whole blood in the four studies. One of these studies (Vazquez, Kazi et al. 1995) aimed to assess the independent effect of protein and carbohydrate intake on plasma ß-hydroxybutylate using four diets with different protein and carbohydrate ratios. The study populations in all four publications included females only, with mean age range of years and mean BMI range of kg/m 2. Prior to the intervention, female subjects received a 3-day weight maintenance diet (composition differed between the studies). Thereafter, they were randomly assigned to receive a ketogenic or nonketogenic diet for the duration of 28 days. In all four studies, the ketogenic diet produced higher concentrations of ketone bodies in whole blood than the nonketogenic diet. Furthermore, Vazqeuz et al 1995 showed that overall carbohydrate intake from the diets affected plasma ß-hydroxybutyrate significantly (P value < 0.001), whereas protein intakes did not (P value = 0.994). Serum acetone In another American study, Foster et al (Foster, Wadden et al. 1992) investigated the effect of 3 diets differing in composition of proteins (70-90 g), carbohydrates ( g), fats (2-20 g) and caloric value ( kcal/day) on weight, FFM, psychological functioning and symptoms. This study was evaluated as high risk of bias. Seventy-six females participated to this study with a mean age of 40.9 ± 2.1 years (420 kcal/day), 38.8 ± 1.7 (660 kcal/day) and 42.1 ± 2.1 years (800 kcal/day). Subjects started the intervention with a 1 week adaptation period, followed by 12 weeks of VLCD and 6 weeks of refeeding period with conventional foods. At the end of week 9 of the intervention, concentrations of serum acetone (mean ± SE) for the 3 dietary interventions were ±120.7 µmol/l (240 kcal/day diet); ± µmol/l (660 kcal/day diet); 75.9 ±51.7 µmol/l (800 kcal/day diet). The difference between the lowest and the highest kcal intervention groups was statistically significant (P value < 0.05). EFSA supporting publication 2015:EN The present document has been produced and adopted by the bodies identified above as author(s). This task has been carried out exclusively by the author(s) in the context of a contract between the European Food Safety Authority and the author(s), awarded following a tender procedure. The present document is published complying with the transparency principle to which the Authority is subject. It may not be considered as an output adopted by the Authority. The European Food Safety Authority reserves its rights, view and position as regards the issues addressed and the conclusions reached in the present document, without prejudice to the

14 Table 3: Ketone body concentrations in ketogenic and nonketogenic diet interventions. Author s n Concentrations of ß-hydroxbutyrate f (mmol/l) at baseline and day 0 and day 28 Non-ketogenic diet ketogenic diet day 0 day 28 day 0 day 28 P value Vazquez et al 1992 a 590 kcal, 50 g protein, 10 g fat and 76 g CHO per day ± 0.1 b < 0.01 c 594 kcal, 52 g protein, 38 g fat and 10 g CHO per day ± 0.5 b Vazquez et al 1994 a 615 kcal, 70 g protein, 3 g fat and 86 g CHO per day ± ± kcal, 70 g protein, 33 g fat and 9 g CHO per day ± ± 0.5 Vazquez et al 1995 a 50P/10C diet: 600 kcal, 50 g protein and 10 g CHO per day ± ± P/75C diet: 600 kcal 50 g protein and 75 g CHO per day ± ± P/10C diet: 600 kcal, 70 g protein and 10 g CHO per day ± ± P/86C diet: 600 kcal, 70 g protein and 86 g CHO per day ± ± 0.05 Wing et al 1995 a e 590 kcal, 50 g protein, 10 g fat and 76 g CHO per day ± ± kcal, 52 g protein, 38 g fat and 10 g CHO per day ± ± 0.4 a All subjects received a 3 day meat-free weight maintenance diet, Wing et al: weight maintenance diet provided 100 g protein and 12555KJ (3000 kcal/day). b Results were derived from a figure in the original publication. c Refers to the comparison between ketogenic and nonketogneic diet at day 28 d Refers to the overall macronutrient (carbohydrate or protein) effect between the four diets e Same diet as in Vazquez et al 1992 f ß-hydroxybutyrate measured in whole blood in Vazquez et al 1992 and in plasma in the remaining three studies. < 0.05 c P Carbohydrate < d P Protein d < c EFSA supporting publication 2015:EN

15 Diets enriched with fatty acids and ketosis Two publications (Krotkiewski 2001; Kunesova, Braunerova et al. 2006) studied the effects of diets enriched with fatty acids on ketosis. The study by Krotkiewski et al., evaluated as having moderate risk of bias, investigated the effect of Medium Chain Triglycerides (MCT) supplementation compared to Long Chain Triglycerides (LCT) during a VLCD on ketosis. MCTs are known to be energetically less dense, highly ketogenic, and more easily oxidized than LCT. They also differ in their digestive and metabolic pathway. Sixty-six Swedish females participated to this study; they were recruited by an advertisement in a daily newspaper. Out of 66 subjects, 22 were randomly assigned to a control group (VLCD with a low fat content; 3 g LCT) From the remaining 44, 22 subjects were assigned to the intervention group; VLCD with MCT (9.9 g) and 22 subjects to the placebo group; VLCD with LCT (8.8 g). The MCT- and LCT-groups were pair matched for BMI, age, body fat, waist to hip ratio and duration of obesity. Mean age ± SE was 42.6 ± 3.7 years (MCT diet), 43.1 ± 4.2 years (LCT diet) and 44.8 ± 3.4 years (low fat diet). In addition, mean BMI ± SE (kg/m 2 ) was 34.1 ± 0.3 (MCT diet), 34.1 ± 0.5 (LCT diet) and 33.1 ± 0.6 (low fat diet). The diets were administered during a period of 4 weeks and provided kcal/day. Serum ß-hydroxybutyrate was measured at baseline and after 24 days of treatment. The MCT diet group showed significantly higher concentrations of ketone bodies after treatment (results presented in figure 2 of the original publication). Kunesova et al. aimed to investigate the influence of VLCD supplemented with n-3 PUFAs on weight loss and serum fatty acid composition in 20 obese females in the Czech Republic. In this publication, the risk of bias was evaluated as moderate. After one week of eucaloric baseline stabilization period, subjects were randomly assigned to a 3-week VLCD supplemented with n-3 PUFA (2.8 g/day) or placebo (saline solution). The intervention also included daily light to moderate physical activity lasting about 60 min. Mean age was 54.3 ± 5.4 years in the n-3 PUFA group and 49.8 ± 12.4 years in the placebo group. Mean BMI was 40.6 ± 4.1 kg/m2 in the n-3 PUFA group and 45.1 ± 6.9 kg/m2 in the placebo group. As an indicator of ketosis, serum ß-hydroxybutyrate was measured and higher increase in ß-hydroxybutyrate concentrations was found in the n-3 PUFA group compared with the placebo group (P value < 0.01) Metabolic acidosis In the publication of Vazquez et al. (Vazquez and Adibi 1992) (study described in ), safety of the diets (ketogenic vs. nonketogenic) was assessed by means of metabolic acidosis. Patients consuming the ketogenic diet developed mild metabolic acidosis compared with patients consuming the nonketogenic diet (ph 7.37 ± 0.01 vs ± 0.01, P value < 0.05) Protein sparing Dieting can impose the risk of losing lean body mass. Nutrient composition of those diets may influence this loss. Six studies reported on the effect of diet on protein sparing parameters (loss of FFM, nitrogen balance and/or the rate of nitrogen oxidation) (Foster, Wadden et al. 1992; Stanko, Tietze et al. 1992; Vazquez and Adibi 1992; Vazquez and Kazi 1994; Vazquez, Kazi et al. 1995; Krotkiewski 2001) and are described below Ketogenic diet and protein sparing Three comparable studies from the USA (Vazquez and Adibi 1992; Vazquez and Kazi 1994; Vazquez, Kazi et al. 1995), all evaluated as having moderate risk of bias, investigated the protein sparing effect EFSA supporting publication 2015:EN The present document has been produced and adopted by the bodies identified above as author(s). This task has been carried out exclusively by the author(s) in the context of a contract between the European Food Safety Authority and the author(s), awarded following a tender procedure. The present document is published complying with the transparency principle to which the Authority is subject. It may not be considered as an output adopted by the Authority. The European Food Safety Authority reserves its rights, view and position as regards the issues addressed and the conclusions reached in the present document, without prejudice to the

16 of the ketogenic and isocaloric isonitrogenous nonketogenic diet(s) for a period of 28 days. Nitrogen balance or nitrogen oxidation rate was used as an indicator for protein sparing effect in the body. In the first study (Vazquez and Adibi 1992), 16 female subjects followed a 3-day weight maintenance diet and were afterwards randomly assigned to receive either a ketogenic (590 kcal/day and 10 g carbohydarates) or nonketogenic diet (594 kcal/day and 76 g carbohydrates). Mean age (in years) ± SEM at baseline was 45 ± 4 in the ketogenic group and 43 ± 5 in the nonketogenic diet group. Mean BMI (kg/m 2 ) ± SEM at baseline was 47 ± 2 in the ketogenic group and 49 ± 4 in the nonketogenic diet group. The cumulative nitrogen balance (g/4 weeks) was significantly less negative in patients consuming the nonketogenic diet (-18.8 ± 5.7) than those who consumed the ketogenic diet (-50.4 ± 4.4; P value < 0.02). The results indicated that nonketogenic VLCD is superior to a ketogenic VLCD in protein sparing due to several mechanisms, including lower urinary nitrogen excretion and less negative cumulative nitrogen balance. The second study by Vazquez et al 1994 (Vazquez and Kazi 1994) included 16 female subjects who were randomly assigned to a ketogenic diet (615 kcal/day and 9 grams of carbohydrates) or a nonketogenic diet (615 kcal/day and 86 g of carbohydrates) after a 3-day weight maintenance diet. The ketogenic and nonketogenic VLCD groups were comparable with respect to age (in years ± SEM; 48 ± 3 vs 44 ±5) and BMI (kg/m 2 ± SEM; 41 ± 5 vs 37 ± 6). The rate of protein oxidation was measured as an indicator of protein sparing, and was found to be mean ± SEM; 59 ± 3 g/day in the ketogenic diet group and 50 ± 3 g/day in the nonketogenic diet group. This difference was statistically significant between the groups on day 28 of the intervention (P value < 0.05). Again here, authors concluded that the nonketogenic diet was superior to the ketogenic diet in maintaining normal plasma glucose concentrations and promoting protein sparing. The last publication by Vazquez et al 1995 (Vazquez, Kazi et al. 1995) aimed to assess the independent effect of carbohydrate and protein intakes on protein sparing during VLCD. After a meatfree, weight maintenance diet, 48 female subjects were assigned to one of the four isoenergic diets with varying amounts of protein (P) (50 g/day vs. 70 g/day) and carbohydrates (C) (10 g/day, 75 g/day, or 86 g/day). The results of the study showed that nitrogen balance was: -50 ± 11 mmol/day in the 50 P/10 C group; -15 ± 16 mmol/day in the 50 P/76 C group; -63 ± 15 mmol/day in the 70 P/10 C group; and +8 ± 23 mmol/day in the 70 P/86 C group. No statistical comparison was made between the groups, but the individual effects of carbohydrate and protein contents were assessed by ANOVA using carbohydrate and protein intakes as independent variables. Carbohydrate content of the diet significantly affected nitrogen balance (P value = 0.003), whereas protein (independently from carbohydrate) significantly affected daily urinary ammonia, urea and total nitrogen excretion, but had no significant effect on nitrogen balance (P value = 0.331). The results show that the total protein and carbohydrate intake are both important for protein sparing during weight loss. Also, these effects are found to be additive and the best protein sparing was obtained with VLCD that provided 70 g of protein and 86 g of carbohydrate per day. Foster et al (Foster, Wadden et al. 1992) (study described in section ) investigated the effect of 3 diets; ranging from 420 to 800 kcal/day on several parameters including reduction in FFM (assessed by densitometry). The diet differed also in contents of proteins, carbohydrates and fats. The reduction in FFM (kg) was 3.2 ± 0.7 in the 240 kcal/day groups, 3.3 ± 0.7 in the 660 kcal/day group and 2.9 ± 0.6 in the 800 kcal/day group. This change was not statistically significant Diet enriched with fatty acids and protein sparing Krotkiewski et al (Krotkiewski 2001) investigated the effect of MCT on protein sparing in three groups (LCT group, MCT group and low fat diet group, study described in ). Sixty-six Swedish females participated to this study. Change in FFM (measured using DEXA) and 24 hour urinary EFSA supporting publication 2015:EN The present document has been produced and adopted by the bodies identified above as author(s). This task has been carried out exclusively by the author(s) in the context of a contract between the European Food Safety Authority and the author(s), awarded following a tender procedure. The present document is published complying with the transparency principle to which the Authority is subject. It may not be considered as an output adopted by the Authority. The European Food Safety Authority reserves its rights, view and position as regards the issues addressed and the conclusions reached in the present document, without prejudice to the