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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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Increased ultra-processed food consumption is associated with worsening of cardiometabolic risk factors in adults with metabolic syndrome: Longitudinal analysis from a randomized trial.
González-Palacios, S, Oncina-Cánovas, A, García-de-la-Hera, M, Martínez-González, MÁ, Salas-Salvadó, J, Corella, D, Schröder, H, Martínez, JA, Alonso-Gómez, ÁM, Wärnberg, J, et al
Atherosclerosis. 2023;377:12-23
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Evidence is increasing linking the consumption of ultra-processed foods (UPF) and an increased risk for the development of heart disease. However, there is still uncertainty surrounding how changes in UPF consumption can affect heart disease risk factors. This secondary analysis of a randomised control trial, which looked at the effects of an energy restricted Mediterranean diet in combination with exercise on the prevention of heart disease, aimed to determine how changes in UPF consumption can affect indicators of heart disease risk over a 12-month period. The results showed that high UPF consumption was associated with higher heart disease risk factors including weight, body mass index, waist circumference, diastolic blood pressure, blood sugar levels, measures of insulin resistance, and triglycerides. Further detrimental effects were seen with UPF consumption increasing, and high-density lipoprotein cholesterol decreasing. No associations were seen with systolic blood pressure, total cholesterol, and low-density lipoprotein cholesterol. It was concluded that high UPF consumption has a detrimental effect on heart disease risk. This study could be used by healthcare professionals to recommend a diet low or devoid of UPF to stay heart healthy.
Abstract
BACKGROUND AND AIMS The association between changes in ultra-processed food (UPF) consumption and cardiometabolic risk (CMR) factors remains understudied. We evaluated the association between changes in UPF consumption over 12 months of follow-up and changes in CMR factors in adults diagnosed with metabolic syndrome. METHODS We analysed data from 5373 adults (aged 55-75 years) participating in the PREDIMED-Plus trial. Diet was evaluated at baseline, 6- and 12-month visits using a validated food frequency questionnaire, and UPF consumption (in grams/day and percentage of total daily dietary intake in grams) was categorized based on NOVA classification. We used mixed-effects linear models with repeated measurements at baseline, 6 and 12 months of follow-up to assess the associations between changes in UPF consumption and changes in CMR factors adjusting for sociodemographic and lifestyles variables. RESULTS In multivariable-adjusted models, when comparing the highest versus the lowest quartile of UPF consumption, positive associations were found for several CMR factors: weight (kg, β = 1.09; 95% confidence interval 0.91 to 1.26); BMI (kg/m2, β = 0.39; 0.33 to 0.46); waist circumference (cm, β = 1.03; 0.81 to 1.26); diastolic blood pressure (mm Hg, β = 0.67; 0.29 to 1.06); fasting blood glucose (mg/dl, β = 1.66; 0.61 to 2.70); HbA1c (%, β = 0.04; 0.01 to 0.07); triglycerides (mg/dl, β = 6.79; 3.66 to 9.91) and triglycerides and glucose index (β = 0.06; 0.04 to 0.08). CONCLUSIONS Higher UPF consumption was associated with adverse evolution in objectively measured CMR factors after 12 months of follow-up in adults with metabolic syndrome. Further research is needed to explore whether these changes persist for longer periods.
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Dietary Glycemic Index and Load and the Risk of Type 2 Diabetes: Assessment of Causal Relations.
Livesey, G, Taylor, R, Livesey, HF, Buyken, AE, Jenkins, DJA, Augustin, LSA, Sievenpiper, JL, Barclay, AW, Liu, S, Wolever, TMS, et al
Nutrients. 2019;11(6)
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It is generally accepted that certain diet and lifestyle choices contribute to a person’s risk of developing type 2 diabetes (T2D). In this meta-analysis, researchers set out to review previous studies and assess whether there is any evidence that the amount and type of carbohydrate (measured by Glycaemic Index (GI) and Glycaemic Load (GL)) in a person’s diet has a direct influence on their risk of developing T2D. The authors concluded with a high level of confidence that eating high GI and GL foods can lead to a higher risk of developing T2D. They suggest that nutrition advice that favours low GI and GL foods could produce significant cost savings for public healthcare.
Abstract
While dietary factors are important modifiable risk factors for type 2 diabetes (T2D), the causal role of carbohydrate quality in nutrition remains controversial. Dietary glycemic index (GI) and glycemic load (GL) have been examined in relation to the risk of T2D in multiple prospective cohort studies. Previous meta-analyses indicate significant relations but consideration of causality has been minimal. Here, the results of our recent meta-analyses of prospective cohort studies of 4 to 26-y follow-up are interpreted in the context of the nine Bradford-Hill criteria for causality, that is: (1) Strength of Association, (2) Consistency, (3) Specificity, (4) Temporality, (5) Biological Gradient, (6) Plausibility, (7) Experimental evidence, (8) Analogy, and (9) Coherence. These criteria necessitated referral to a body of literature wider than prospective cohort studies alone, especially in criteria 6 to 9. In this analysis, all nine of the Hill's criteria were met for GI and GL indicating that we can be confident of a role for GI and GL as causal factors contributing to incident T2D. In addition, neither dietary fiber nor cereal fiber nor wholegrain were found to be reliable or effective surrogate measures of GI or GL. Finally, our cost-benefit analysis suggests food and nutrition advice favors lower GI or GL and would produce significant potential cost savings in national healthcare budgets. The high confidence in causal associations for incident T2D is sufficient to consider inclusion of GI and GL in food and nutrient-based recommendations.