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Is telomere length a biomarker of sperm quality? A systematic review and meta-analysis of observational studies.
Fernández de la Puente, M, Salas-Huetos, A, Valle-Hita, C, Babio, N, Murphy, MM, Canudas, S, Salas-Salvadó, J
Andrology. 2024;(2):277-288
Abstract
BACKGROUND Telomeres are essential for the integrity of chromosome ends during cell division and their involvement in different processes linked to aging has been established. These chromosome components are involved in spermatogenesis and seem to play an important role in fertilization and embryo development. Telomere length is shortened with each cell division. Recently, short sperm telomere length has been proposed as a potential biomarker of male infertility. OBJECTIVES To conduct a systematic review and meta-analysis of studies exploring the association between spermatozoa and/or leukocyte telomere length with sperm quality parameters and different infertility conditions. MATERIAL AND METHODS A systematic review and meta-analysis was conducted with studies from Medline-PUBMED and Cochrane Library databases until May 2022. Eligible studies included cohort, cross-sectional and case-control studies, and telomere length in spermatozoa and/or leukocytes cells was defined as the exposure. Semen quality parameters or infertility conditions (e.g., oligozoospermia, asthenozoospermia, teratozoospermia, or other spermatogenic impairment combinations) were defined as the outcomes. RESULTS Twenty-three observational studies were included. In the qualitative analysis, high heterogeneity was observed between studies regarding the associations between telomere length and semen parameters in different normozoospermic/fertile and oligozoospermic/infertile populations. In the meta-analysis, spermatozoa and leukocyte telomere length were shorter in infertile individuals than in fertile individuals (mean difference [95% confidence interval]: -1.43 [-1.66 to -1.21], p-value <0.001 and -1.67 [-2.02 to -1.31], p-value <0.001, respectively). Moreover, in terms of sperm telomere length, these differences were also significant between individuals with a normal seminogram and individuals with a low quantity of spermatozoa in the ejaculate (-0.97 [-1.32, -0.61], p-value <0.001). CONCLUSION The current systematic review and meta-analysis suggests the potential role of spermatozoa or leukocyte telomere length as a reliable biomarker of semen quality, which may help distinguish between infertility conditions beyond the routine semen analysis.
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Lack of association between endocrine disrupting chemicals and male fertility: A systematic review and meta-analysis.
Martínez, MÁ, Marquès, M, Salas-Huetos, A, Babio, N, Domingo, JL, Salas-Salvadó, J
Environmental research. 2023;217:114942
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Exposure to natural or synthetic chemicals is directly related to environmental conditions, dietary and other lifestyle factors. Some of these chemicals are named endocrine disrupting chemicals (EDCs) because of their capability to interfere with the endocrine system. The aim of this study was to summarise and explore the association between exposure to EDCs and human male fertility indicators. This study is a systematic review and meta-analysis of seven studies; 4 assessed bisphenol A (BPA) in urine and sperm quality parameters, while 3 articles evaluated PCB153 [polychlorinated biphenyls] in serum and sperm quality parameters. Results show that there weren’t any positive or inverse associations between BPA or PCB153 and the sperm parameters analysed. Authors conclude that the systematic review showed a high disparity between studies, making difficult a consensus on the possible detrimental effect of the 12 groups of EDCs on male fertility. Thus, no conclusive statements can be drawn. Further studies are needed in order to provide more robust data.
Abstract
The incidence of infertility currently affects about 15% of the world's population. Male factors are estimated to be responsible for up to 40-50% of these cases. While the cause of these reproductive disorders is still unclear, the exposure to a family of ubiquitous compounds in our daily life, named endocrine disrupting chemicals (EDCs) could be involved. This paper was aimed at performing a systematic review and meta-analysis of population studies exploring whether human male exposure to EDCs affects male fertility. Clinical and observational studies assessing the exposure to EDCs along with sperm quality, the most common reproductive disorders, sperm DNA damage, sperm oxidative stress, fertilization rate, implantation rate, clinical pregnancy rate, live birth rate, and miscarriage rate were included. The quality assessment tool from the NHLBI-NIH was used to assure that studies met standardized quality criteria. Sensitivity analysis and heterogeneity among studies was assessed. Overall, the 32 selected articles, including 7825 individuals in the systematic review, explored 12 families of EDCs. The results revealed a high heterogeneity among studies in relation to the association between exposure to EDCs and the endpoints analyzed. Meta-analyses were performed with data from 7 articles including 479 individuals, 4 articles assessing the association between BPA in urine and sperm quality, and 3 articles evaluating PCB153 in serum and sperm quality. In the meta-analysis, we identified an unpredicted significant positive association between PCB153 exposure and sperm concentration. However, it would not be clinically relevant. No positive or inverse associations were found neither for BPA, nor for PCB153 and the rest of sperm parameters analyzed. The high disparity between studies made difficult to draw conclusions on the potential harmful effects of EDCs on male fertility. Consequently, to delineate the potential relationship that EDCs can have on male fertility, an important condition stressing the health system, further investigations are required.
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Vegetable and Fruit Intake Variety and Cardiovascular Health and Mortality: A Systematic Review and Meta-Analysis of Observational Studies.
Nishi, SK, Khoury, N, Valle Hita, C, Zurbau, A, Salas-Salvadó, J, Babio, N
Nutrients. 2023;(23)
Abstract
INTRODUCTION A multitude of evidence supports the consumption of a higher quantity of vegetables and fruits for their cardiovascular benefits. Nonetheless, the extent to which variety is associated with cardiovascular health remains unclear. OBJECTIVE To conduct a systematic review and meta-analysis of observational studies (prospective cohort and cross-sectional studies) assessing the role of a variety of vegetable and fruit consumption in cardiovascular morbidity and mortality in adults. DATA SOURCES MEDLINE-PubMed, Cochrane databases, and reference lists were searched through March 2023. DATA EXTRACTION Two independent reviewers extracted data and assessed the risk of bias (National Heart, Lung, and Blood Institute Tool and Newcastle-Ottawa Scale). DATA ANALYSIS Data were pooled (fixed and random [DerSimonian and Laird] effects for <5 and ≥5 study comparisons, respectively), and heterogeneity was assessed using the Cochran Q statistic and quantified (I2 statistic). The Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) was used to assess the overall certainty of the evidence. Five cross-sectional (n = 45,761) and seven prospective studies (n = 253,422) met the eligibility criteria. Greater variety of vegetable and fruit consumption was prospectively related to decreased all-cause mortality (risk ratio, 0.89 [95% CI, 0.82-0.97], seven study comparisons, n = 196,925), while no significant associations were observed with assessed cardiovascular-related mortality or morbidity. For all outcomes, the certainty of the evidence was graded as "low" or "very low" owing to inconsistency and/or imprecision. CONCLUSIONS Overall, this study shows that greater variety in vegetable and fruit consumption may reduce all-cause mortality and highlights the need for additional studies with a higher degree of evidence to better understand its role in cardiovascular health.
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Nuts and Cardiovascular Disease Outcomes: A Review of the Evidence and Future Directions.
Glenn, AJ, Aune, D, Freisling, H, Mohammadifard, N, Kendall, CWC, Salas-Salvadó, J, Jenkins, DJA, Hu, FB, Sievenpiper, JL
Nutrients. 2023;(4)
Abstract
Nuts are nutrient-rich foods that contain many bioactive compounds that are beneficial for cardiovascular health. Higher consumption of nuts has been associated with a reduced risk of several cardiovascular diseases (CVD) in prospective cohort studies, including a 19% and 25% lower risk of CVD incidence and mortality, respectively, and a 24% and 27% lower risk of coronary heart disease incidence and mortality, respectively. An 18% lower risk of stroke mortality, a 15% lower risk of atrial fibrillation, and a 19% lower risk of total mortality have also been observed. The role of nuts in stroke incidence, stroke subtypes, peripheral arterial disease and heart failure has been less consistent. This narrative review summarizes recommendations for nuts by clinical practice guidelines and governmental organizations, epidemiological evidence for nuts and CVD outcomes, nut-containing dietary patterns, potential mechanisms of nuts and CVD risk reduction, and future research directions, such as the use of biomarkers to help better assess nut intake. Although there are still some uncertainties around nuts and CVD prevention which require further research, as summarized in this review, there is a substantial amount of evidence that supports that consuming nuts will have a positive impact on primary and secondary prevention of CVD.
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Nuts in the Prevention and Management of Type 2 Diabetes.
Nishi, SK, Viguiliouk, E, Kendall, CWC, Jenkins, DJA, Hu, FB, Sievenpiper, JL, Atzeni, A, Misra, A, Salas-Salvadó, J
Nutrients. 2023;(4)
Abstract
Diabetes is a continuously growing global concern affecting >10% of adults, which may be mitigated by modifiable lifestyle factors. Consumption of nuts and their inclusion in dietary patterns has been associated with a range of beneficial health outcomes. Diabetes guidelines recommend dietary patterns that incorporate nuts; however, specific recommendations related to nuts have been limited. This review considers the epidemiological and clinical evidence to date for the role of nut consumption as a dietary strategy for the prevention and management of type 2 diabetes (T2D) and related complications. Findings suggest nut consumption may have a potential role in the prevention and management of T2D, with mechanistic studies assessing nuts and individual nut-related nutritional constituents supporting this possibility. However, limited definitive evidence is available to date, and future studies are needed to elucidate better the impact of nuts on the prevention and management of T2D.
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Combination of Multiple Low-Risk Lifestyle Behaviors and Incident Type 2 Diabetes: A Systematic Review and Dose-Response Meta-analysis of Prospective Cohort Studies.
Khan, TA, Field, D, Chen, V, Ahmad, S, Mejia, SB, Kahleová, H, Rahelić, D, Salas-Salvadó, J, Leiter, LA, Uusitupa, M, et al
Diabetes care. 2023;(3):643-656
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Abstract
OBJECTIVE Combined low-risk lifestyle behaviors (LRLBs) have been associated with a reduction in type 2 diabetes risk. This relationship has not been systematically quantified. RESEARCH DESIGN AND METHODS A systematic review and meta-analysis was conducted to assess the association of combined LRLBs with type 2 diabetes. Databases were searched up to September 2022. Prospective cohort studies reporting the association between a minimum of three combined LRLBs (including healthy diet) with incident type 2 diabetes were included. Independent reviewers extracted data and assessed study quality. Risk estimates of extreme comparisons were pooled using a random-effects model. Global dose-response meta-analysis (DRM) for maximum adherence was estimated using a one-stage linear mixed model. The certainty of the evidence was assessed using GRADE (Grading of Recommendations, Assessment, Development and Evaluations). RESULTS Thirty cohort comparisons (n = 1,693,753) involving 75,669 incident type 2 diabetes cases were included. LRLBs, with author-defined ranges, were healthy body weight, healthy diet, regular exercise, smoking abstinence or cessation, and light alcohol consumption. LRLBs were associated with 80% lower risk of type 2 diabetes (relative risk [RR] 0.20; 95% CI 0.17-0.23), comparing the highest with lowest adherence. Global DRM for maximum adherence to all five LRLBs reached 85% protection (RR 0.15; 95% CI 0.12-0.18). The overall certainty of the evidence was graded as high. CONCLUSIONS There is a very good indication that a combination of LRLBs that includes maintaining a healthy bodyweight, healthy diet, regular exercise, smoking abstinence or cessation, and light alcohol consumption is associated with a lower risk of incident type 2 diabetes.
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Effects of Nut Consumption on Blood Lipids and Lipoproteins: A Comprehensive Literature Update.
Guasch-Ferré, M, Tessier, AJ, Petersen, KS, Sapp, PA, Tapsell, LC, Salas-Salvadó, J, Ros, E, Kris-Etherton, PM
Nutrients. 2023;(3)
Abstract
In the present review, we provide a comprehensive narrative overview of the current knowledge on the effects of total and specific types of nut consumption (excluding nut oil) on blood lipids and lipoproteins. We identified a total of 19 systematic reviews and meta-analyses of randomized controlled trials (RCTs) that were available in PubMed from the inception date to November 2022. A consistent beneficial effect of most nuts, namely total nuts and tree nuts, including walnuts, almonds, cashews, peanuts, and pistachios, has been reported across meta-analyses in decreasing total cholesterol (mean difference, MD, -0.09 to -0.28 mmol/L), LDL-cholesterol (MD, -0.09 to -0.26 mmol/L), and triglycerides (MD, -0.05 to -0.17 mmol/L). However, no effects on HDL-cholesterol have been uncovered. Preliminary evidence indicates that adding nuts into the regular diet reduces blood levels of apolipoprotein B and improves HDL function. There is also evidence that nuts dose-dependently improve lipids and lipoproteins. Sex, age, or nut processing are not effect modifiers, while a lower BMI and higher baseline lipid concentrations enhance blood lipid/lipoprotein responses. While research is still emerging, the evidence thus far indicates that nut-enriched diets are associated with a reduced number of total LDL particles and small, dense LDL particles. In conclusion, evidence from clinical trials has shown that the consumption of total and specific nuts improves blood lipid profiles by multiple mechanisms. Future directions in this field should include more lipoprotein particle, apolipoprotein B, and HDL function studies.
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Comment on Muzzioli et al. Are Front-of-Pack Labels a Health Policy Tool? Nutrients 2022, 14, 771.
Aguenaou, H, Babio, N, Deschasaux-Tanguy, M, Galan, P, Hercberg, S, Julia, C, Jones, A, Karpetas, G, Kelly, B, Kesse-Guyot, E, et al
Nutrients. 2022;(10)
Abstract
As scientists working and publishing in the field of front-of-pack nutrition labelling (FOPNL) for many years, we have read with interest and concern the narrative review regarding their effectiveness by Muzzioli et al. [...].
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The link between cognition and somatic conditions related to insulin resistance in the UK Biobank study cohort: a systematic review.
Fanelli, G, Mota, NR, Salas-Salvadó, J, Bulló, M, Fernandez-Aranda, F, Camacho-Barcia, L, Testa, G, Jiménez-Murcia, S, Bertaina-Anglade, V, Franke, B, et al
Neuroscience and biobehavioral reviews. 2022;:104927
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Clinical and genomic studies have shown an overlap between neuropsychiatric disorders and insulin resistance (IR)-related somatic conditions, including obesity, type 2 diabetes, and cardiovascular diseases. Impaired cognition is often observed among neuropsychiatric disorders, where multiple cognitive domains may be affected. In this review, we aimed to summarise previous evidence on the relationship between IR-related diseases/traits and cognitive performance in the large UK Biobank study cohort. Electronic searches were conducted on PubMed, Scopus, and Web of Science until April 2022. Eighteen articles met the inclusion criteria and were qualitatively reviewed. Overall, there is substantial evidence for an association between IR-related cardio-metabolic diseases/traits and worse performance on various cognitive domains, which is largely independent of possible confoundings. The most consistent findings referred to IR-related associations with poorer verbal and numerical reasoning ability, as well as slower processing speed. The observed associations might be mediated by alterations in immune-inflammation, brain integrity/connectivity, and/or comorbid somatic or psychiatric diseases/traits. Our findings provide impetus for further research into the underlying neurobiology and possible new therapeutic targets.
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Relation of Change or Substitution of Low- and No-Calorie Sweetened Beverages With Cardiometabolic Outcomes: A Systematic Review and Meta-analysis of Prospective Cohort Studies.
Lee, JJ, Khan, TA, McGlynn, N, Malik, VS, Hill, JO, Leiter, LA, Jeppesen, PB, Rahelić, D, Kahleová, H, Salas-Salvadó, J, et al
Diabetes care. 2022;(8):1917-1930
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BACKGROUND Adverse associations of low- and no-calorie sweetened beverages (LNCSB) with cardiometabolic outcomes in observational studies may be explained by reverse causality and residual confounding. PURPOSE To address these limitations we used change analyses of repeated measures of intake and substitution analyses to synthesize the association of LNCSB with cardiometabolic outcomes. DATA SOURCES MEDLINE, Embase, and the Cochrane Library were searched up to 10 June 2021 for prospective cohort studies with ≥1 year of follow-up duration in adults. STUDY SELECTION Outcomes included changes in clinical measures of adiposity, risk of overweight/obesity, metabolic syndrome, type 2 diabetes (T2D), cardiovascular disease, and total mortality. DATA EXTRACTION Two independent reviewers extracted data, assessed study quality, and assessed certainty of evidence using GRADE. Data were pooled with a random-effects model and expressed as mean difference (MD) or risk ratio (RR) and 95% CI. DATA SYNTHESIS A total of 14 cohorts (416,830 participants) met the eligibility criteria. Increase in LNCSB intake was associated with lower weight (5 cohorts, 130,020 participants; MD -0.008 kg/year [95% CI -0.014, -0.002]). Substitution of LNCSB for sugar-sweetened beverages (SSB) was associated with lower weight (three cohorts, 165,579 participants; MD, -0.12 [-0.14, -0.10,] kg/y) and lower incidence of obesity (OB) (one cohort, 15,765 participants; RR 0.88 [95% CI 0.88, 0.89]), coronary heart disease (six cohorts, 233,676 participants; 0.89 [0.81, 0.98]), cardiovascular disease mortality (one cohort, 118,363 participants; 0.95 [0.90, 0.99]), and total mortality (one cohort, 118,363 participants; 0.96 [0.94, 0.98]) with no adverse associations across other outcomes. Substitution of water for SSB showed lower weight (three cohorts, 165,579 participants; MD -0.10 kg/year [-0.13, -0.06]), lower waist circumference (one cohort, 173 participants; -2.71 cm/year [-4.27, -1.15]) and percent body fat (one cohort, 173 participants; -1.51% per year [-2.61, -0.42]), and lower incidence of OB (one cohort, 15,765 participants; RR 0.85 [0.75, 0.97]) and T2D (three cohorts, 281,855 participants; 0.96 [0.94, 0.98]). Substitution of LNCSB for water showed no adverse associations. LIMITATIONS The evidence was low to very low certainty owing to downgrades for imprecision, indirectness, and/or inconsistency. CONCLUSIONS LNCSB were not associated with cardiometabolic harm in analyses that model the exposure as change or substitutions. The available evidence provides some indication that LNCSB in their intended substitution for SSB may be associated with cardiometabolic benefit, comparable with the standard of care, water.