title: Composition differences between organic and conventional meat: a systematic literature review and meta-analysis.
abstract: Demand for organic meat is partially driven by consumer perceptions that organic foods are more nutritious than non-organic foods. However, there have been no systematic reviews comparing specifically the nutrient content of organic and conventionally produced meat. In this study, we report results of a meta-analysis based on sixty-seven published studies comparing the composition of organic and non-organic meat products. For many nutritionally relevant compounds (e.g. minerals, antioxidants and most individual fatty acids (FA)), the evidence base was too weak for meaningful meta-analyses. However, significant differences in FA profiles were detected when data from all livestock species were pooled. Concentrations of SFA and MUFA were similar or slightly lower, respectively, in organic compared with conventional meat. Larger differences were detected for total PUFA and n-3 PUFA, which were an estimated 23 (95 % CI 11, 35) % and 47 (95 % CI 10, 84) % higher in organic meat, respectively. However, for these and many other composition parameters, for which meta-analyses found significant differences, heterogeneity was high, and this could be explained by differences between animal species/meat types. Evidence from controlled experimental studies indicates that the high grazing/forage-based diets prescribed under organic farming standards may be the main reason for differences in FA profiles. Further studies are required to enable meta-analyses for a wider range of parameters (e.g. antioxidant, vitamin and mineral concentrations) and to improve both precision and consistency of results for FA profiles for all species. Potential impacts of composition differences on human health are discussed.
authors.affiliation: 1Nafferton Ecological Farming Group (NEFG),School of Agriculture, Food and Rural Development,Newcastle University,Nafferton Farm,Stocksfield,Northumberland NE43 7XD,UK.
authors.forename: Dominika
authors.initials: D
authors.lastname: Średnicka-Tober
authors.affiliation: 1Nafferton Ecological Farming Group (NEFG),School of Agriculture, Food and Rural Development,Newcastle University,Nafferton Farm,Stocksfield,Northumberland NE43 7XD,UK.
authors.forename: Marcin
authors.initials: M
authors.lastname: Barański
authors.affiliation: 2School of Agriculture, Food and Rural Development,Human Nutrition Research Centre,Newcastle University,Agriculture Building,Kings Road,Newcastle upon Tyne NE1 7RU,UK.
authors.forename: Chris
authors.identifier: http://orcid.org/0000-0001-6313-6691
authors.initials: C
authors.lastname: Seal
authors.affiliation: 3School of Biology,Newcastle University,Ridley Building,Newcastle upon Tyne NE1 7RU,UK.
authors.forename: Roy
authors.initials: R
authors.lastname: Sanderson
authors.affiliation: 4Benbrook Consulting Services,90063 Troy Road,Enterprise,OR 97828,USA.
authors.forename: Charles
authors.initials: C
authors.lastname: Benbrook
authors.affiliation: 5Food and Agriculture Division - Grassland and Forage,Norwegian Institute of Bioeconomy Research (NIBIO),Gunnars veg 6,N-6630 Tingvoll,Norway.
authors.forename: Håvard
authors.initials: H
authors.lastname: Steinshamn
authors.affiliation: 6Department of Dietetics, Faculty of Human Nutrition and Consumer Sciences,Warsaw University of Life Sciences,Nowoursynowska 159c,02-776 Warsaw,Poland.
authors.forename: Joanna
authors.initials: J
authors.lastname: Gromadzka-Ostrowska
authors.affiliation: 7Department of Functional and Organic Food and Commodities, Faculty of Human Nutrition and Consumer Sciences,Warsaw University of Life Sciences,Nowoursynowska 159c,02-776 Warsaw,Poland.
authors.forename: Ewa
authors.initials: E
authors.lastname: Rembiałkowska
authors.affiliation: 8Department of Animal Physiology, Faculty of Biology,University of Warsaw,Miecznikowa 1,02-096 Warsaw,Poland.
authors.forename: Krystyna
authors.initials: K
authors.lastname: Skwarło-Sońta
authors.affiliation: 1Nafferton Ecological Farming Group (NEFG),School of Agriculture, Food and Rural Development,Newcastle University,Nafferton Farm,Stocksfield,Northumberland NE43 7XD,UK.
authors.forename: Mick
authors.initials: M
authors.lastname: Eyre
authors.affiliation: 9Department of Animal Medicine, Production and Health,University of Padua,Viale dell' Università 19,35020 Legnaro,Italy.
authors.forename: Giulio
authors.initials: G
authors.lastname: Cozzi
authors.affiliation: 10Department of Food Science - Food Chemistry & Technology,Aarhus University,Blichers Allé 20,Building F20/8845,8830 Tjele,Denmark.
authors.forename: Mette
authors.initials: M
authors.lastname: Krogh Larsen
authors.affiliation: 1Nafferton Ecological Farming Group (NEFG),School of Agriculture, Food and Rural Development,Newcastle University,Nafferton Farm,Stocksfield,Northumberland NE43 7XD,UK.
authors.forename: Teresa
authors.initials: T
authors.lastname: Jordon
authors.affiliation: 11Research Institute for Organic Agriculture (FiBL),Ackerstrasse 113,CH-5070 Frick,Switzerland.
authors.forename: Urs
authors.initials: U
authors.lastname: Niggli
authors.affiliation: 12Institute of Genetics and Animal Breeding,Polish Academy of Science,Jastrzębiec,Postępu 36,05-552 Magdalenka,Poland.
authors.forename: Tomasz
authors.initials: T
authors.lastname: Sakowski
authors.affiliation: 13Human Development and Health Academic Unit, Faculty of Medicine,University of Southampton,Southampton SO16 6YD,UK.
authors.forename: Philip C
authors.initials: PC
authors.lastname: Calder
authors.affiliation: 13Human Development and Health Academic Unit, Faculty of Medicine,University of Southampton,Southampton SO16 6YD,UK.
authors.forename: Graham C
authors.initials: GC
authors.lastname: Burdge
authors.affiliation: 14National Agricultural Research Foundation (NAGREF),Veterinary Research Institute of Thessaloniki,57001 Thermi,Thessaloniki,Greece.
authors.forename: Smaragda
authors.initials: S
authors.lastname: Sotiraki
authors.affiliation: 14National Agricultural Research Foundation (NAGREF),Veterinary Research Institute of Thessaloniki,57001 Thermi,Thessaloniki,Greece.
authors.forename: Alexandros
authors.initials: A
authors.lastname: Stefanakis
authors.affiliation: 1Nafferton Ecological Farming Group (NEFG),School of Agriculture, Food and Rural Development,Newcastle University,Nafferton Farm,Stocksfield,Northumberland NE43 7XD,UK.
authors.forename: Halil
authors.initials: H
authors.lastname: Yolcu
authors.affiliation: 1Nafferton Ecological Farming Group (NEFG),School of Agriculture, Food and Rural Development,Newcastle University,Nafferton Farm,Stocksfield,Northumberland NE43 7XD,UK.
authors.forename: Sokratis
authors.initials: S
authors.lastname: Stergiadis
authors.affiliation: 1Nafferton Ecological Farming Group (NEFG),School of Agriculture, Food and Rural Development,Newcastle University,Nafferton Farm,Stocksfield,Northumberland NE43 7XD,UK.
authors.forename: Eleni
authors.initials: E
authors.lastname: Chatzidimitriou
authors.affiliation: 1Nafferton Ecological Farming Group (NEFG),School of Agriculture, Food and Rural Development,Newcastle University,Nafferton Farm,Stocksfield,Northumberland NE43 7XD,UK.
authors.forename: Gillian
authors.initials: G
authors.lastname: Butler
authors.affiliation: 1Nafferton Ecological Farming Group (NEFG),School of Agriculture, Food and Rural Development,Newcastle University,Nafferton Farm,Stocksfield,Northumberland NE43 7XD,UK.
authors.forename: Gavin
authors.initials: G
authors.lastname: Stewart
authors.affiliation: 1Nafferton Ecological Farming Group (NEFG),School of Agriculture, Food and Rural Development,Newcastle University,Nafferton Farm,Stocksfield,Northumberland NE43 7XD,UK.
authors.forename: Carlo
authors.initials: C
authors.lastname: Leifert
mesh_terms: D000822:Animal Husbandry; D000818:Animals; D004032:Diet / Q000662:veterinary*; D055317:Evidence-Based Practice; D058870:Food, Organic / Q000032:analysis*; D006801:Humans; D058751:Livestock / Q000254:growth & development; D008460:Meat / Q000032:analysis*; D008461:Meat Products / Q000032:analysis; D009753:Nutritive Value
keywords:     n-3 PUFA;     n-6 PUFA; ALA 
                    α-linolenic acid; Animal products; DMI DM intake; DPA docosapentaenoic acid; EU European Union; FA fatty acids; Iron; LA linoleic acid; MPD mean percentage difference; Meat; Meat fat composition; Organic foods; SMD standardised mean difference; UM unweighted meta-analysis; VLC very long-chain FA; WM weighted meta-analysis