Nuts and Human Health Outcomes: A Systematic Review

nutrients Review Nuts and Human Health Outcomes: A Systematic Review Rávila Graziany Machado de Souza, Raquel Machado Schincaglia, Gustavo Duarte Pimentel and João Felipe Mota * ID Clinical and Sports Nutrition Research Laboratory (LABINCE), Faculty of Nutrition, Goiás Federal University, Goiânia 74605-080, Brazil; (R.G.M.d.S.); (R.M.S.); (G.D.P.) * Correspondence: ; Tel.: +55-(62)-3209-6270 Received: 22 September 2017; Accepted: 9 November 2017; Published: 2 December 2017 Abstract: There has been increasing interest in nuts and their outcome regarding human health. The consumption of nuts is frequently associated with reduction in risk factors for chronic diseases. Although nuts are high calorie foods, several studies have reported beneficial effects after nut consumption, due to fatty acid profiles, vegetable proteins, fibers, vitamins, minerals, carotenoids, and phytosterols with potential antioxidant action. However, the current findings about the benefits of nut consumption on human health have not yet been clearly discussed. This review highlights the effects of nut consumption on the context of human health. Keywords: tree nuts; health; obesity; body weight; cancer 1. Introduction There is increasing interest in nut consumption and human health outcomes [1]. Nuts are commonly consumed in the Mediterranean diet, and their consumption has been recommended to populations all over the world [2]. Tree nuts, such as almonds, hazelnuts, cashew nuts, Brazil nuts, macadamias, walnuts, and pistachios, as well as legume seeds, such peanuts, are nutrient-dense foods each with a unique composition. In general, these foods contain healthy monounsaturated (MUFA) and polyunsaturated (PUFA) fatty acid profiles; protein; soluble and insoluble fibers; vitamins E and K; folate; thiamine; minerals such as magnesium, copper, potassium, and selenium; and substances such as zanthophyll carotenoids, antioxidants, and phytosterols compounds, with recognized benefits to human health [3–5]. Prior reviews and epidemiological and/or clinical trials have suggested that regular nut consumption has beneficial impact on health outcomes, such as obesity [6], hypertension [7], diabetes mellitus [8], and cardiovascular diseases [3], with reduction in mediators of chronic diseases such as oxidative stress, inflammation, visceral adiposity, hyperglycemia, insulin resistance, endothelial dysfunction, and metabolic syndrome [9]. Furthermore, several prospective studies and clinical trials have reported beneficial effects after nut consumption. However, the current findings about the main benefits of the consumption of each nut type on human health have not yet been discussed. In addition, main nutritional components and practical implications regarding nut consumption in humans need to be better clarified. Therefore, in this systematic review, we highlight the effects of nut consumption on human health. 2. Method We used the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) method to systematically review the articles that assessed the effects of nut consumption on human Nutrients 2017, 9, 1311; doi:10.3390/nu9121311 www.mdpi.com/journal/nutrients Nutrients 2017, 9, 1311 2 of 23 Identification health. This systematic review was registered in International prospective register of systematic Nutrients 2017, 9, 1312 with the number CRD42017077466. We conducted the review using the 2electronic of 23 reviews (PROSPERO) ® ® database PubMed /MEDLINE (https://www.ncbi.nlm.nih.gov/pubmed/) and by searching clinical reviews (PROSPERO) with the number CRD42017077466. We conducted the review using the trials published from 2007 to July 2017 that were published in journals with an impact factor (according electronic database PubMed®/MEDLINE® (https://www.ncbi.nlm.nih.gov/pubmed/) and by to thesearching Journal of Citation Reports) of ≥ 1.0. The criteria to define a “clinical trial” was based on studies clinical trials published from 2007 to July 2017 that were published in journals with an with impact humans that(according were prospectively toReports) one or more include factor to the Journalassigned of Citation of ≥1.0.interventions The criteria to (which define a may “clinical placebo or other control groups), and with the aim to evaluate the effects of interventions with trial” was based on studies with humans that were prospectively assigned to one or more nuts on human health.(which Since may the Medical Subjector Headings (MeSH) is the National of Medicine interventions include placebo other control groups), and with theLibrary aim to evaluate ® /MEDLINE thecontrolled effects of interventions nuts on human health. Since the Medical Headings (MeSH)® we (NLM) vocabularywith thesaurus used for indexing articles forSubject PubMed National of Medicine (NLM)yielded controlled thesaurus used for indexing used isit the to select the Library index terms. The search the vocabulary following keywords: almonds, Brazil nut, ®/MEDLINE® we used it to select the index terms. The search yielded the articles for PubMed cashew nut, hazelnut, macadamia, peanuts, pistachio, walnut, tree nuts, ground nut, diabetes, obesity, following keywords: almonds, Brazil nut, cashew nut, hazelnut, macadamia, peanuts, pistachio, dyslipidemia, heart disease, cancer, body weight, digestion, food intake, human health, inflammation, walnut, tree nuts, ground nut, diabetes, obesity, dyslipidemia, heart disease, cancer, body weight, and oxidative stress. The Boolean operators “and”, “or”, and “and not” were used to combine the terms digestion, food intake, human health, inflammation, and oxidative stress. The Boolean operators used “and”, in the literature review. The initial search consisted of screening titles and abstracts, whereas the “or”, and “and not” were used to combine the terms used in the literature review. The initial second step consisted reviewing articleswhereas to confirm the study The information search consisted ofof screening titlesfull-text and abstracts, the second stepselection. consisted of reviewing extracted from each individual study wasselection. as follows: of publication, objective, nutindividual type, portion full-text articles to confirm the study Theyear information extracted from each size, study and relationship to human The search strategy andportion the total of evaluated and selected was as follows: year ofhealth. publication, objective, nut type, size, and relationship to human health. in TheFigure search1.strategy and the totalsearch, of evaluated and selected studies are in this studies are shown As a result of the 49 studies were selected. In shown addition, Figure 1. As a result of the search, 49 studies were selected. In addition, this review included the review included the citation of nine articles that were used to define the scientific terms and discuss citation of nine articles that were used to define the scientific terms and discuss the results. the results. (...truncated)