The healthy Nordic diet has been previously shown to have health beneficial effects among subjects at risk of CVD. However, the extent of food changes needed to achieve these effects is less explored. The aim of the present study was to investigate the effects of exchanging a few commercially available, regularly consumed key food items (e.g. spread on bread, fat for cooking, cheese, bread and cereals) with improved fat quality on total cholesterol, LDL-cholesterol and inflammatory markers in a double-blind randomised, controlled trial. In total, 115 moderately hypercholesterolaemic, non-statin-treated adults (25-70 years) were randomly assigned to an experimental diet group (Ex-diet group) or control diet group (C-diet group) for 8 weeks with commercially available food items with different fatty acid composition (replacing SFA with mostly n-6 PUFA). In the Ex-diet group, serum total cholesterol (P < 0·001) and LDL-cholesterol (P < 0·001) were reduced after 8 weeks, compared with the C-diet group. The difference in change between the two groups at the end of the study was −9 and −11 % in total cholesterol and LDL-cholesterol, respectively. No difference in change in plasma levels of inflammatory markers (high-sensitive C-reactive protein, IL-6, soluble TNF receptor 1 and interferon-γ) was observed between the groups. In conclusion, exchanging a few regularly consumed food items with improved fat quality reduces total cholesterol, with no negative effect on levels of inflammatory markers. This shows that an exchange of a few commercially available food items was easy and manageable and led to clinically relevant cholesterol reduction, potentially affecting future CVD risk.

Popular scientific summary • The Nordic and Baltic countries are developing a common scientific basis for national nutrition recommendations. • The project is commissioned by the Nordic Council of Ministers. • A comprehensive organizational model with 'checks and balances' was developed. • Contemporary evidence-based principles and methodologies based on the best available evidence were defined.

Popular scientific summary • The process to develop systematic reviews (SRs) requires a step-by-step predefined approach. • This article describes a detailed procedure for developing qualified SRs in the Nordic Nutrition Recommendations 2022 (NNR2022) project. • The new protocol represents an important update compared to corresponding guide developed for the fifth edition of the NNR.

Background: As part of the process of updating national dietary reference values (DRVs) and food-based dietary guidelines (FBDGs), the Nordic Nutrition Recommendations 2022 project (NNR2022) will select a limited number of topics for systematic reviews (SRs). Objective: To develop and transparently describe the results of a procedure for prioritisation of topics that may be submitted for SRs in the NNR2022 project. Design: In an open call, scientists, health professionals, national food and health authorities, food manufacturers, other stakeholders and the general population in the Nordic and Baltic countries were invited to suggest SR topics. The NNR2022 Committee developed scoping reviews (ScRs) for 51 nutrients and food groups aimed at identifying potential SR topics. These ScRs included the relevant nominations from the open call. SR topics were categorised, ranked and prioritised by the NNR2022 Committee in a modified Delphi process. Existing qualified SRs were identified to omit duplication. Results: A total of 45 nominations with suggestion for more than 200 exposure–outcome pairs were received in the public call. A number of additional topics were identified in ScRs. In order to omit duplication with recently qualified SRs, we defined criteria and identified 76 qualified SRs. The NNR2022 Committee subsequently shortlisted 52 PI/ECOTSS statements, none of which overlapped with the qualified SRs. The PI/ECOTSS statements were then graded ‘High’ (n = 21), ‘Medium’ (n = 9) or ‘Low’ (n = 22) importance, and the PI/ECOTSS statements with ‘High’ were ranked in a Delphi process. The nine top prioritised PI/ECOTSS included the following exposure–outcome pairs: 1) plant protein intake in children and body growth, 2) pulses/legumes intake, and cardiovascular disease and type 2 diabetes, 3) plant protein intake in adults, and atherosclerotic/cardiovascular disease and type 2 diabetes, 4) fat quality and mental health, 5) vitamin B12 and vitamin B12 status, 6) intake of white meat (no consumption vs. high consumption and white meat replaced with red meat), and all-cause mortality, type 2 diabetes and risk factors, 7) intake of n-3 LPUFAs from supplements during pregnancy, and asthma and allergies in the offspring, 8) nuts intake and cardiovascular disease (CVD) and type 2 diabetes in adults, 9) dietary fibre intake (high vs. low) in children and bowel function. Discussion: The selection of topics for de novo SRs is central in the NNR2022 project, as the results of these SRs may cause adjustment of existing DRVs and FBDGs. That is why we have developed this extensive process for the prioritisation of SR topics. For transparency, the results of the process are reported in this publication. Conclusion: The principles and methodologies developed in the NNR2022 project may serve as a framework for national health authorities or organisations when developing national DRVs and FBDGs. This collaboration between the food and health authorities in Denmark, Estonia, Finland, Iceland, Latvia, Lithuania, Norway and Sweden represents an international effort for harmonisation and sharing of resources and competence when developing national DRVs and FBDGs.

Background Replacing dietary saturated fatty acids (SFAs) with polyunsaturated fatty acids (PUFA) reduces the plasma low-density lipoprotein (LDL) cholesterol and subsequently the risk of cardiovascular disease. However, beyond changes in LDL cholesterol, we lack a complete understanding of the physiologic alterations that occur when improving dietary fat quality. Objectives The aim of this study was to gain knowledge of metabolic alterations paralleling improvements in the fat quality of the diet. Methods We recently conducted an 8-wk, double-blind, randomized controlled trial replacing SFAs with PUFAs in healthy subjects with moderate hypercholesterolemia (n = 99). In the present substudy, we performed comprehensive metabolic profiling with multiple platforms (both nuclear magnetic resonance- and mass spectrometry-based technology) (n = 99), and analyzed peripheral blood mononuclear cell gene expression (n = 95) by quantitative real-time polymerase chain reaction. Results A large number of lipoprotein subclasses, myristoylcarnitine and palmitoylcarnitine, and kynurenine were reduced when SFAs were replaced with PUFAs. In contrast, bile acids, proprotein convertase subtilisin/kexin type 9, acetate, and acetoacetate were increased by the intervention. Some amino acids were also altered by the intervention. The mRNA levels of LXRA and LDLR were increased, in addition to several liver X receptor α target genes and genes involved in inflammation, whereas the mRNA levels of UCP2 and PPARD were decreased in peripheral blood mononuclear cells after replacing SFAs with PUFAs. Partial least squares-discriminant analysis showed that the 30 most important variables that contributed to class separation spanned all classes of biomarkers, and was in accordance with the univariate analysis. Conclusions Applying metabolomics in randomized controlled dietary intervention trials has the potential to extend our knowledge of the biological and molecular effects of dietary fat quality. This study was registered at clinicaltrials.gov as NCT 01679496.

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Popular scientific summary • Qualified systematic review (SRs) (i.e. high-quality SRs) are the preferred method for evaluating causal effects of nutrients or food groups on health outcomes in NNR2022. • Most SRs published in scientific journals do not fulfill all criteria of a qualified SR. • This article discusses the structure and rationale of qualified SRs in NNR2022.

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