ObjectivesTo examine the effect of nut consumption on inflammatory biomarkers and endothelial function.DesignA systematic review and meta-analysis.Data sourcesMEDLINE, PubMed, Cumulative Index to Nursing and Allied Health Literature and Cochrane Central Register of Controlled Trials (all years to 13 January 2017).Eligibility criteriaRandomised controlled trials (with a duration of 3 weeks or more) or prospective cohort designs conducted in adults; studies assessing the effect of consumption of tree nuts or peanuts on C-reactive protein (CRP), adiponectin, tumour necrosis factor alpha, interleukin-6, intercellular adhesion molecule 1, vascular cell adhesion protein 1 and flow-mediated dilation (FMD).Data extraction and analysisRelevant data were extracted for summary tables and analyses by two independent researchers. Random effects meta-analyses were conducted to explore weighted mean differences (WMD) in change or final mean values for each outcome.ResultsA total of 32 studies (all randomised controlled trials) were included in the review. The effect of nut consumption on FMD was explored in nine strata from eight studies (involving 652 participants), with consumption of nuts resulting in significant improvements in FMD (WMD: 0.79%(95% CI 0.35 to 1.23)). Nut consumption resulted in small, non-significant differences in CRP (WMD: −0.01 mg/L (95% CI −0.06 to 0.03)) (26 strata from 25 studies), although sensitivity analyses suggest results for CRP may have been influenced by two individual studies. Small, non-significant differences were also found for other biomarkers of inflammation.ConclusionsThis systematic review and meta-analysis of the effects of nut consumption on inflammation and endothelial function found evidence for favourable effects on FMD, a measure of endothelial function. Non-significant changes in other biomarkers indicate a lack of consistent evidence for effects of nut consumption on inflammation. The findings of this analysis suggest a need for more research in this area, with a particular focus on randomised controlled trials.PROSPERO registration number CRD42016045424.

IntroductionDietary phytochemicals are found in plant-based foods such as fruits, vegetables and grains and may be categorised in a nested hierarchical manner with many hundred individual phytochemicals identified to date. To associate phytochemical intakes with positive health outcomes, a fundamental step is to accurately estimate the dietary phytochemical intake from foods reported. The purpose of this systematic review protocol is to describe the process to be undertaken to summarise the evidence for food-based dietary phytochemical intakes and health outcomes for adults.Methods and analysisThe review will be undertaken following the PRISMA guidelines and the Cochrane Handbook for Systematic Reviews of Interventions using the Review Manager software. Phytochemical subclasses (phenolic acids, flavanols, etc) will be used to search for relevant studies using the Web of Science and Scopus scientific databases. The retrieved studies will be screened based on inclusion of natural whole food items and health outcomes. Phytochemical studies related to cardiovascular disease, cancer, overweight, glucose tolerance, digestive, reproductive, macular and bone health and mental disorders, fatigue and immunity will be examined based on prior scoping. The evidence will be aggregated by the food types and health outcomes. Comparison of differences in the outcomes for randomised controlled trials and observational studies will be undertaken. The strength of the review lies in its focus on whole food items and health conditions rather than one type of phytochemical related to one single health condition. Subgroup and sensitivity analyses will be conducted where an adequate number of publications are found per phytochemical subclass.DisseminationBy comparing the outcomes from experimental and observational studies, the review will determine whether the overall conclusions related to the phytochemical subclasses are the same between study types for the identified health conditions. This is useful to public health policymakers and health professionals alike.Trial registration number#CRD42014015610.

Translating food intake data into phytochemical outcomes is a crucial step in investigating potential health benefits. The aim of this review was to examine the tools for determining dietary-derived polyphenol intakes for estimated intake studies. Published studies from 2004 to 2014 reporting polyphenol food composition information were sourced with 157 studies included. Six polyphenol subclasses were identified. One quarter of studies (n=39) reported total flavonoids intake with 27% reporting individual flavonoid compounds. Assessing multiple compounds was common with approximately 10% of studies assessing seven (n=13), six (n=12) and five (n=14) subclasses of polyphenol. There was no pattern between reported flavonoids compounds and subclass studied. Approximately 60% of studies relied on publicly accessible food composition data to estimate dietary polyphenols intake with 33% using two or more tools. This review highlights the importance of publicly accessible composition databases for estimating polyphenol intake and provides a reference for tools available globally.