Dietary patterns and semen quality: a systematic review and meta-analysis of observational studies
TL;DR: Healthy dietary pattern seems to be associated with elevated sperm concentration level, but no significant association was seen between eating patterns and other semen quality.
Abstract: A number of studies have examined the association between dietary patterns and semen quality, but the findings have been inconclusive. Herein, we conducted a systematic review and meta-analysis of observational studies to assess the association between dietary patterns and semen quality. PubMed, Cochrane library, Science direct, Scopus, Google Scholar, and ISI web of science databases were searched up to August 2016 for observational studies assessing the association between common dietary patterns and sperm quality markers. Data were pooled by the generic inverse variance method with random effects and expressed as mean differences with 95% confidence intervals (CIs). Heterogeneity was assessed (Cochrane Q-statistic) and quantified (I2 -statistic). The Newcastle-Ottawa Scale assessed study quality. Six eligible studies, involving 8207 participants, were included in our systematic review and meta-analysis. The pooled mean difference of sperm concentration for the healthy dietary pattern versus unhealthy dietary pattern intake was mean difference: 0.66; 95% CI, 0.305-1.016; p < 0.001. In comparison with those who had the highest adherence to healthy dietary pattern, individuals in the lowest adherence had significantly lower level of sperm concentration. However, no significant association was seen between eating patterns and other semen quality. Healthy dietary pattern seems to be associated with elevated sperm concentration level. Further longitudinal studies are needed to clarify this relationship.
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TL;DR: The evidence from this meta-analysis suggests that FI has a significant effect on the likelihood of being stressed or depressed, and indicates that health care services, which alleviate FI, would also promote holistic well-being in adults.
Abstract: Objective Food security has been suggested to be a risk factor for depression, stress and anxiety. We therefore undertook a systematic review and meta-analysis of available publications to examine these associations further. Design Relevant studies were identified by searching Web of Science, Embase, Scopus and PubMed databases up to January 2019. Setting OR was pooled using a random-effects model. Standard methods were used for assessment of heterogeneity and publication bias. Participants Data were available from nineteen studies with 372 143 individual participants from ten different countries that were pooled for the meta-analysis. Results The results showed there was a positive relationship between food insecurity (FI) and risk of depression (OR = 1·40; 95 % CI: 1·30, 1·58) and stress (OR = 1·34; 95 % CI: 1·24, 1·44) but not anxiety. Subgroup analysis by age showed that subjects older than ≥65 years exhibited a higher risk of depression (OR = 1·75; 95 % CI: 1·20, 2·56) than younger participants (OR = 1·34; 95 % CI: 1·20, 1·50), as well as a greater risk of depression in men (OR = 1·42; 95 % CI: 1·17, 1·72) than women (OR = 1·30; 95 % CI: 1·16, 1·46). Finally, subgroup analysis according to geographical location illustrated that food insecure households living in North America had the highest risk of stress and anxiety. Conclusions The evidence from this meta-analysis suggests that FI has a significant effect on the likelihood of being stressed or depressed. This indicates that health care services, which alleviate FI, would also promote holistic well-being in adults.
168 citations
TL;DR: A wide-ranging vision of the positive associations and effects of diet on sperm quality is provided and adherence to healthy dietary patterns is positively associated with sperm concentration and sperm motility.
65 citations
TL;DR: This is the first study to indicate that exposure to POPs may increase the proportion of ejaculated Y-bearing spermatozoa, and this data add to the growing body of evidence that exposure of endocrine disruptors may alter the offspring sex ratio.
44 citations
TL;DR: It is found that MD could alleviate NAFLD severity parameters but differences between studies should be taken into account and more clinical trials with adequate sample size and better methodology should be done.
Abstract: Summary Background Dietary habit can play a key role in the prevention and treatment of fatty liver disease (NAFLD). Although many studies have investigated the effect of Mediterranean diet on NAFLD, findings are inconsistent and there is no systematic review on this topic. Therefore, the aim of this systematic review is to summarize the effect of Mediterranean diet on serum metabolic indices and anthropometric measures among NAFLD patients. Methods We searched titles, abstracts, and keywords of articles indexed in Science Direct, MEDLINE, and Google Scholar databases up to October 2018 to identify eligible RCT studies. Randomized clinical trials assessing the effects of MD on NAFLD were included. Results The present study included 10 randomized controlled trials, which involved a total of 856 adults with NAFLD. According to the result, MD may improve anthropometric measures, lipid profile, glycemic indices, liver enzyme, and NAFLD severity indices among patients with NAFLD. Conclusion We found that MD could alleviate NAFLD severity parameters but differences between studies should be taken into account. Finally, in order to draw a firm link between MD and NAFLD, more clinical trials with adequate sample size and better methodology should be done.
36 citations
05 Feb 2020
TL;DR: This cross-sectional study assesses whether adherence to specific dietary patterns is associated with testicular function and semen quality in young Danish men.
Abstract: Importance Diet may play a role in testicular function, but data on how adherence to different diet patterns influences human testicular function are scarce. Objective To determine whether adherence to specific dietary patterns is associated with testicular function in young men. Design, Setting, and Participants This cross-sectional study included 2935 young Danish men unselected regarding fertility status who were enrolled from April 1, 2008, through May 31, 2017. Data were analyzed from July 1, 2017, to January 30, 2019. Exposures Dietary patterns identified with principal component analysis based on responses to a validated food frequency questionnaire. Main Outcomes and Measures Standard semen quality assessment; serum concentrations of testosterone, free testosterone, estradiol, inhibin B, follicle-stimulating hormone, luteinizing hormone, and sex hormone–binding globulin; and testicular volume measured with ultrasonography. Results Among the 2935 participants included in the analysis, median age was 19 (interquartile range, 19-20) years and 2290 (78.0%) had normal body mass index. The 4 dietary patterns identified included Western, prudent, open-sandwich (a traditional Danish eating pattern), and vegetarianlike. The greatest adherence to the prudent pattern was associated with the highest total sperm count (median, 167 [95% CI, 146-183] million), followed by adherence to vegetarianlike (median, 151 [95% CI, 134-168] million) and open-sandwich (median, 146 [95% CI, 131-163] million) patterns. Adherence to the Western pattern was associated with the lowest total sperm count (median, 122 [95% CI, 109-138] million), which was significantly lower than sperm count in the other 3 diet patterns. After adjusting for confounders, the median total sperm count for men in the highest quintile of adherence to the Western pattern was 26 million lower (95% CI, –42 to –9 million) than for men in the lowest quintile of adherence to this pattern. Conversely, the median total sperm count of men in the highest quintile of adherence to the prudent pattern was 43 million (95% CI, 23-63 million) higher than that of men in the lowest quintile. Men with the highest adherence to the Western pattern had a lower median ratio of inhibin B to follicle-stimulating hormone (–12 [95% CI, –20 to –3]) and higher median ratio of free testosterone to luteinizing hormone (10 [95% CI, 2-19]) compared with men with lowest adherence to this pattern. Conclusions and Relevance In this cross-sectional study, adherence to generally healthy diet patterns was associated with better semen quality, with potentially more favorable fertility potential among adult men.
25 citations
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01 Jan 2014
TL;DR: The Newcastle-Ottawa Scale (NOS) as discussed by the authors was developed to assess the quality of nonrandomised studies with its design, content and ease of use directed to the task of incorporating the quality assessments in the interpretation of meta-analytic results.
Abstract: Nonrandomised studies, including case-control and cohort studies, can be challenging to implement and conduct. Assessment of the quality of such studies is essential for a proper understanding of nonrandomised studies. The Newcastle-Ottawa Scale (NOS) is an ongoing collaboration between the Universities of Newcastle, Australia and Ottawa, Canada. It was developed to assess the quality of nonrandomised studies with its design, content and ease of use directed to the task of incorporating the quality assessments in the interpretation of meta-analytic results. A 'star system' has been developed in which a study is judged on three broad perspectives: the selection of the study groups; the comparability of the groups; and the ascertainment of either the exposure or outcome of interest for case-control or cohort studies respectively. The goal of this project is to develop an instrument providing an easy and convenient tool for quality assessment of nonrandomised studies to be used in a systematic review.
17,590 citations
TL;DR: Two simple formulas are found that estimate the mean using the values of the median, low and high end of the range, and n (the sample size) and these hope to help meta-analysts use clinical trials in their analysis even when not all of the information is available and/or reported.
Abstract: Usually the researchers performing meta-analysis of continuous outcomes from clinical trials need their mean value and the variance (or standard deviation) in order to pool data. However, sometimes the published reports of clinical trials only report the median, range and the size of the trial. In this article we use simple and elementary inequalities and approximations in order to estimate the mean and the variance for such trials. Our estimation is distribution-free, i.e., it makes no assumption on the distribution of the underlying data. We found two simple formulas that estimate the mean using the values of the median (m), low and high end of the range (a and b, respectively), and n (the sample size). Using simulations, we show that median can be used to estimate mean when the sample size is larger than 25. For smaller samples our new formula, devised in this paper, should be used. We also estimated the variance of an unknown sample using the median, low and high end of the range, and the sample size. Our estimate is performing as the best estimate in our simulations for very small samples (n ≤ 15). For moderately sized samples (15 70), the formula range/6 gives the best estimator for the standard deviation (variance). We also include an illustrative example of the potential value of our method using reports from the Cochrane review on the role of erythropoietin in anemia due to malignancy. Using these formulas, we hope to help meta-analysts use clinical trials in their analysis even when not all of the information is available and/or reported.
6,384 citations
"Dietary patterns and semen quality:..." refers background or methods in this paper
...Two studies reported means and 95% CIs (Gaskins et al., 2012; Cutillas-Tolin et al., 2015), and the remaining reported medians and ranges (Vujkovic et al., 2009; Liu et al., 2015) which we transformed into means and SEs by a formula (Hozo et al., 2005)....
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..., 2015) which we transformed into means and SEs by a formula (Hozo et al., 2005)....
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TL;DR: Semen quality of the reference population was superior to that of the men from the general population and normozoospermic men, and provide an appropriate tool in conjunction with clinical data to evaluate a patient's semen quality and prospects for fertility.
Abstract: BACKGROUND Semen quality is taken as a surrogate measure of male fecundity in clinical andrology, male fertility, reproductive toxicology, epidemiology and pregnancy risk assessments. Reference intervals for values of semen parameters from a fertile population could provide data from which prognosis of fertility or diagnosis of infertility can be extrapolated. METHODS Semen samples from over 4500 men in 14 countries on four continents were obtained from retrospective and prospective analyses on fertile men, men of unknown fertility status and men selected as normozoospermic. Men whose partners had a time-to-pregnancy (TTP) of < or =12 months were chosen as individuals to provide reference distributions for semen parameters. Distributions were also generated for a population assumed to represent the general population. RESULTS The following one-sided lower reference limits, the fifth centiles (with 95th percent confidence intervals), were generated from men whose partners had TTP < or = 12 months: semen volume, 1.5 ml (1.4-1.7); total sperm number, 39 million per ejaculate (33-46); sperm concentration, 15 million per ml (12-16); vitality, 58% live (55-63); progressive motility, 32% (31-34); total (progressive + non-progressive) motility, 40% (38-42); morphologically normal forms, 4.0% (3.0-4.0). Semen quality of the reference population was superior to that of the men from the general population and normozoospermic men. CONCLUSIONS The data represent sound reference distributions of semen characteristics of fertile men in a number of countries. They provide an appropriate tool in conjunction with clinical data to evaluate a patient's semen quality and prospects for fertility.
2,264 citations
"Dietary patterns and semen quality:..." refers background in this paper
...The association between healthy dietary pattern and sperm total motility The term ‘total motility’ refers to a fraction of spermatozoa which shows any kind of movements (Cooper et al., 2010)....
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...The association between healthy dietary pattern and sperm total motility The term ‘total motility’ refers to a fraction of spermatozoa which shows any kind of movements (Cooper et al., 2010)....
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TL;DR: High levels of ROS are detrimental to the fertility potential both in natural and assisted conception states.
1,348 citations
"Dietary patterns and semen quality:..." refers background in this paper
...Intake of antioxidants and carotenoids has been studied for their potential effect against ROS generation and may play a critical role in protecting male germ cells against oxidative damage and also a treatment for idiopathic oxidative stress in spermatozoa (Aitken, 1989; Fraga et al., 1991; Agarwal et al., 2003; Gharagozloo & Aitken, 2011; Rafieian-Kopaei et al., 2013; Showell et al., 2014; Hajibabaei, 2016)....
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...…play a critical role in protecting male germ cells against oxidative damage and also a treatment for idiopathic oxidative stress in spermatozoa (Aitken, 1989; Fraga et al., 1991; Agarwal et al., 2003; Gharagozloo & Aitken, 2011; Rafieian-Kopaei et al., 2013; Showell et al., 2014; Hajibabaei, 2016)....
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TL;DR: This review will provide an overview of oxidative biochemistry related to sperm health and identify which men are most at risk of oxidative infertility, and outline methods available for diagnosing oxidative stress and the various treatments available.
Abstract: Oxidative stress occurs when the production of potentially destructive reactive oxygen species (ROS) exceeds the bodies own natural antioxidant defenses, resulting in cellular damage. Oxidative stress is a common pathology seen in approximately half of all infertile men. ROS, defined as including oxygen ions, free radicals and peroxides are generated by sperm and seminal leukocytes within semen and produce infertility by two key mechanisms. First, they damage the sperm membrane, decreasing sperm motility and its ability to fuse with the oocyte. Second, ROS can alter the sperm DNA, resulting in the passage of defective paternal DNA on to the conceptus. This review will provide an overview of oxidative biochemistry related to sperm health and will identify which men are most at risk of oxidative infertility. Finally, the review will outline methods available for diagnosing oxidative stress and the various treatments available.
1,231 citations
"Dietary patterns and semen quality:..." refers background in this paper
...Reactive Oxygen Species (ROS) production has been associated with loss of motility and a decreased capacity for spermatozoa–oocyte fusion (Saleh et al., 2003; Tremellen, 2008; Ross et al., 2010)....
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