Semen quality according to prenatal coffee and present caffeine exposure: two decades of follow-up of a pregnancy cohort

Maternal coffee consumption and biomarkers of reproductive health in young, adult sons: a cohort study

It has been proposed that poor semen quality may have its origins from fetal programming due to environmental factors. We investigated whether maternal coffee consumption during early pregnancy was associated with biomarkers of reproductive health in adult sons in the Fetal Programming of Semen Quality (FEPOS) cohort. In 2017-2019, 1058 young men provided a semen and blood sample and self-measured their testis volume. Daily maternal coffee consumption was reported by the mothers around gestational week 17. We estimated relative percentage differences with 95 % confidence intervals (CI) for semen quality measures, testis volume, and reproductive hormone levels according to maternal coffee consumption during pregnancy. Maternal coffee consumption (yes/no (reference)) was associated with lower semen volume (-7.0 % (95 % CI:-12.9;-0.7)), lower proportion of morphologically normal spermatozoa (-8.3 % (95 % CI:-16.5;0.8)), higher proportion of non-progressive and immotile spermatozoa (4.3 % (95 % CI:-1.5;10.3)), and lower testis volume (-4.8 % (95 % CI:-9.0;-0.4)). No indication of a dose-response association or threshold effects was observed in the categorized and continuous analyses. No associations with reproductive hormone levels were observed in any of the analyses. Overall, the study does not provide obvious indications that maternal coffee consumption in early pregnancy deteriorates male offspring fecundity. While some minor changes were observed, most estimates were small with confidence intervals overlapping the null. Future studies, preferably with greater exposure contrast, are warranted before a conclusion can be drawn as to whether maternal coffee consumption during pregnancy constitutes a risk for reproductive health in adult sons.

Diet and recreational drug use in relation to male reproductive health

Diet and lifestyle interventions present promising avenues for the improvement of male fertility. Our objective was to review and synthesize the existing observational and experimental studies among humans on the associations of diet and recreational drug use with semen quality and fertility outcomes. The available data on this topic are limited and, at times, conflicting. Nevertheless, on the basis of this review, dietary patterns that are composed of higher intakes of fruits, vegetables, whole grains, nuts, low-fat dairy, and seafood, as well as lower intakes of red and processed meats, sweets, and sugar-sweetened beverages were identified as having the strongest evidence for associations with better sperm quality. However, whether these dietary patterns translate into positive associations with clinical fertility endpoints such as assisted reproductive technology success rates or time-to-pregnancy among couples trying to conceive without medical assistance remains unclear. Male caffeine and alcohol intake, within low-to-moderate ranges of intake, do not appear to be detrimental to semen quality. Yet high-quality research on this topic, focused on clinical fertility endpoints, should continue given the conflicting evidence, particularly in populations undergoing infertility treatment with assisted reproductive technology. Recreational drug use, including marijuana, electronic cigarettes, and other illicit drugs, does not appear to be beneficial for male reproductive health and should be avoided or ceased. In conclusion, men should be encouraged to consume a healthy diet rich in fruits, vegetables, whole grains, nuts, low-fat dairy, and seafood, as well as lacking in red and processed meats, sweets, and sugar-sweetened beverages, and to avoid recreational drug use for improved male reproductive health.

Genotoxic effects of caffeine in female mice exposed during pregnancy and lactation period and their offspring

Caffeine is a widely consumed substance, and there is a discussion about its effects when ingested by women during pregnancy and lactation. We aimed to identify the genotoxic effects of caffeine in female mice that consumed it during pregnancy and lactation periods and its consequences in their offspring. Thirty-six couples of Swiss mice received water or caffeine (0.3 and 1.0 mg/mL) treatment during pregnancy and lactation. The male and female offspring were divided into 12 groups according to the treatment administered to the female mice. Genotoxicity was assessed using the comet assay and the micronucleus test. Both doses of caffeine showed genotoxic effects in pregnant and lactating mice groups compared to groups not administered caffeine. In relation to offspring, it can be observed that females and males of the offspring had low weight in early life. In both female and male offspring, genotoxicity was detected in the blood, liver, and kidney tissues. Thus, from the present study, we can suggest that the caffeine consumed by female mice during the periods of pregnancy and lactation led to genotoxic effects in their offspring.

Effects of Exercise on Testosterone and Implications of Drug Abuse: A Review

OBJECTIVE

Research points to exercise having a positive effect in fighting relapse and use of drugs of abuse. Through conducting this research, differences have been observed in the effects of exercise on drug abuse between sexes. Many of the studies found that exercise tends to cause a more profound effect in blocking drug relapse or reinstatement in males when compared with females.

METHODS

Our hypothesis is that these differences in response to drugs of abuse after an exercise regimen could in part be attributed to variations in testosterone levels between males and females.

RESULTS

Testosterone has been shown to have a modulatory impact on the dopaminergic activity in the brain, causing an effect on the brain's response to drugs of abuse. Exercise has demonstrated a causal effect on increasing testosterone levels in males, whereas drugs of abuse decrease testosterone levels in males.

CONCLUSIONS

Thus, exercise raising testosterone levels in males helps to decrease the dopaminergic response in the brain to drugs of abuse causing attenuation to drugs. To find sex-specific exercise treatments for drugs of abuse, it is important to continue researching exercise's efficacy against drugs of abuse.

Addiction and human male fertility: A systematic review and a critical appraisal

BACKGROUND

Addiction is a global problem that has many negative consequences on human health as well as the quality of life.

OBJECTIVES

This review aimed to assess the effect of addiction on human male fertility.

METHODS

A systematic review was conducted on various electronic sites.

RESULTS

The initial literature search identified a total of 5239 articles in all searched databases. After removing duplicates and application of inclusion/exclusion criteria,177 were potential articles, 112 were omitted because no direct relevance was encountered. Finally, 65 studies were retained for review. They were classified according to the type of addiction into; opioids and cannabinoids (18 articles), alcohol (7 articles), cocaine (2 articles), Androgenic Anabolic steroids AAS (15 articles), tobacco (10 articles) and caffeine (13 articles). Most of these recruited articles demonstrated a negative impact of the addressed substance on male fertility with variable levels of evidence.

CONCLUSIONS

It was concluded that addiction harms human male fertility that should be put into consideration. More future studies are needed after a proper methodological and statistical approach, including logistic regression analysis, to predict the effect of a specific substance on human male fertility. This article is protected by copyright. All rights reserved.

The association between caffeine intake and testosterone: NHANES 2013-2014

Background

Caffeine is one of the most commonly used psychoactive drugs in the world, and provides many health benefits including alertness, improved memory, and reducing inflammation. Despite these benefits, caffeine has been implicated in a number of adverse health outcomes possibly due to effects within the endocrine system, effects that may contribute to impaired reproductive function and low testosterone in men. Previous studies have investigated associations between caffeine consumption and testosterone levels in men, although the quantity and generalizability of these studies is lacking, and the results between studies are conflicting and inconclusive.

Methods

Using data from a cross-sectional study of 372 adult men in the 2013–2014 NHANES survey cycle, the researchers set out to characterize the association between serum testosterone levels, caffeine, and 14 caffeine metabolites.

Results

Multivariable, weighted linear regression revealed a significant inverse association between caffeine and testosterone. Multivariable, linear regression revealed significant, inverse associations between 6 xanthine metabolic products of caffeine and testosterone. Inverse associations were observed between 5-methyluric acid products and testosterone, as well as between 5-acetlyamino-6-amino-3-methyluracil and testosterone. A significant, positive association was observed for 7-methyl xanthine, 3,7-dimethyluric acid, and 7-methyluric acid. Logistic regression models to characterize the association between 2 biologically active metabolites of caffeine (theobromine and theophylline) and odds of low testosterone (< 300 ng/dL) were non-significant.

Conclusions

These findings suggest a potential role for caffeine’s contribution to the etiology of low testosterone and biochemical androgen deficiency. Future studies are warranted to corroborate these findings and elucidate biological mechanisms underlying this association.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12937-022-00783-z.

Energy drinks may affect the ovarian reserve and serum anti-mullerian hormone levels in a rat model

Objective

Energy drinks have an impact on concentration levels, physical performance, speed of reaction, and focus, but these drinks cause many adverse effects and intoxication symptoms. The main goal of this study was to determine the effect of energy drink consumption on ovarian reserve and serum anti-mullerian hormone (AMH) levels.

Materials and Methods

Female Wistar albino rats (n=16) were included and randomized into two groups (n=8). Serum AMH levels were checked before and after energy drinks were given. Eight weeks later, the ovaries and uteruses of the rats were analyzed histopathologically. The number of follicles in the ovaries was counted.

Results

The total number of the preantral plus small antral follicles, which show the ovarian reserve, was decreased at the end of eight weeks in both the control group and the energy drink group. There was a statistical difference between them (p=0.021). Also, there was a statistically significant difference in the initial/final AMH (ng/mL) reduction levels between the control group and the energy drink group (p=0.002). AMH levels were decreased more in the energy drink group.

Conclusion

The consumption of energy drinks can lead to a decrease in ovarian reserve and AMH values and may cause weight gain.

Nutrition, genetic variation and male fertility

Infertility affects nearly 50 million couples worldwide, with 40-50% of cases having a male factor component. It is well established that nutritional status impacts reproductive development, health and function, although the exact mechanisms have not been fully elucidated. Genetic variation that affects nutrient metabolism may impact fertility through nutrigenetic mechanisms. This review summarizes current knowledge on the role of several dietary components (vitamins A, B₁₂, C, D, E, folate, betaine, choline, calcium, iron, caffeine, fiber, sugar, dietary fat, and gluten) in male reproductive health. Evidence of gene-nutrient interactions and their potential effect on fertility is also examined. Understanding the relationship between genetic variation, nutrition and male fertility is key to developing personalized, DNA-based dietary recommendations to enhance the fertility of men who have difficulty conceiving.

Occupational use of agrochemicals results in inhibited cholinesterase activity and altered reproductive hormone levels in male farmers from Buea, Cameroon

The efficiency of agro pesticides and fertilizers in eliminating pests and scaling up crop yield has motivated farmers to increase their use. Unfortunately, health hazards caused on farmers by these agrochemicals are of growing concern, though not well elucidated. In order to evaluate the effects of occupational exposure to agrochemicals on some key parameters of male farmers' health in Buea Subdivision, Cameroon, a total of 101 men, including 62 farmers using the agrochemicals and a reference population of 39 men not involved in occupational utilization of the agrochemicals, were interviewed on use of protective equipment, exposure symptoms and reproductive health status. Thereafter, serum cholinesterase [acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE)] activities, total antioxidant capacity and reproductive hormones [follicle-stimulating hormone (FSH), luteinizing hormone and testosterone] were assessed. Results revealed that farmers mainly used insecticides followed by fungicides, herbicides and fertilizers, but with inadequate protective measures. The use of agrochemicals resulted in several exposure symptoms including weakness, itches, burning sensation, headache, sneezing, coughing and vomiting, as well as decrease in serum AChE activity when compared to the reference population. The agrochemicals impacted negatively on the farmers' reproductive health as evidenced by increased FSH levels. Taken altogether, these results suggested that exposure to agrochemicals adversely affects farmers' health. Therefore, there is a need to further sensitize the farmers on the use of protective equipment to mitigate the exposure and resulting health hazards.

The effects of caffeine on ovarian tissue in rats

Caffeine consumption increases during early adulthood, which has adverse effects on the reproductive system. This study aimed to assess the impact of embryonic caffeine exposure on rat ovary in adulthood. Female Wistar rats (240-270 g) were divided into 5 groups (n = 7): experimental groups were exposed to 26, 45, 100, and 150 mg/kg of caffeine via drinking water during pregnancy and the control group only received drinking water. The ovaries of the offspring were taken out on days 7, 14, 28, 60, 90, and 120 of postnatal development, and then, they were fixed in 10% formaldehyde solution. Ovarian follicles were studied using stereological methods, and data were analyzed using one-way ANOVA followed by the Tukey test in SPSS software. A value of p < 0.05 was considered significant. The body weight, the weight of the ovaries, the ovarian volume, and the number of primordial follicles decreased significantly (p < 0.05) in 45 and 100 mg/kg, and (p < 0.001) in 150 mg/kg caffeine-treated groups at all stages of postnatal development. Significant decreases were observed in the number of primary and secondary follicles in 45 and 100 mg/kg (p < 0.05) and (p < 0.001) in 150 mg/kg caffeine-treated groups on days 7, 14, 28, and 60 compared to the control group. The number of Graafian follicles also decreased significantly (p < 0.001) in 45, 100, and 150 mg/kg caffeine-treated groups on days 14 and 28. Moreover, the mean volume of the oocyte in Graafian follicles reduced considerably in 45, 100, and 150 mg/kg caffeine-treated groups compared to other groups (p < 0.05). The thickness of the zona pellucida (ZP) in the secondary follicles (p < 0.02) and Graafian follicles (p < 0.05) showed a significant reduction in 100 and 150 mg/kg caffeine-treated groups on the 14th, 28th, and 60th days. In conclusion, high-dose caffeine consumption during gestation affects all stages of ovarian follicle development in rat offspring.

Do lifestyle practices impede male fertility?

Alongside an increasing prevalence of couple and male infertility, evidence suggests there is a global declining trend in male fertility parameters over the past few decades. This may, at least in part, be explained through detrimental lifestyle practices and exposures. These include alcohol and tobacco consumption, use of recreational drugs (e.g., cannabis, opioids and anabolic steroids), poor nutritional habits, obesity and metabolic syndrome, genital heat stress (e.g., radiation exposure through cell phones and laptops, prolonged periods of sitting, tight-fitting underwear and recurrent hot baths or saunas), exposure to endocrine-disrupting chemicals (e.g., pesticide residue, bisphenol A, phthalates and dioxins) and psychological stress. This review discusses these lifestyle practices and the current evidence associated with male infertility. Furthermore, known mechanisms of action are also discussed for each of these. Common mechanisms associated with a reduction in spermatogenesis and/or steroidogenesis due to unfavourable lifestyle practices include inflammation and oxidative stress locally or systemically. It is recommended that relevant lifestyle practices are investigated in clinical history of male infertility cases, particularly in unexplained or idiopathic male infertility. Appropriate modification of detrimental lifestyle practices is further suggested and recommended in the management of male infertility.

The effect of modifiable lifestyle factors on semen quality

INTRODUCTION AND OBJECTIVES

To examine the association between lifestyle factors (body mass index, smoking, alcohol consumption, coffee intake, physical activity, sauna and cell phone usage, wearing tight-fitting underwear), and conventional semen parameters.

MATERIALS AND METHODS

1311 participants who attended the Andrology Clinic were included in the study. All participants were separated into two groups as men with normozoospermia and dysspermia. All participants answered a questionnaire which contains questions about the modifiable lifestyle factors. The total risk scores were calculated after all the positive lifestyle factors had been counted.

RESULTS

Men with normozoospermia and dysspermia consisted of 852 (65.0%) and 459 (35.0%) participants respectively. A negative relationship between the wearing of tight underwear and having normal semen parameters was detected between the two groups (p=0.004). While going to a sauna regularly was negatively related to semen concentration, wearing tight underwear was also related to both lower motility, normal morphology as well as semen concentration (p<0.05). While the total score of all participants was 5.22±1.34 point, there were no statistical differences between the two groups (p=0.332). It was found that having 3 more or fewer points was not related to any type of semen parameters and results of a spermiogram.

CONCLUSION

The clinicians should give advice to infertile male patients about changing their risky lifestyle, for infertility, to a healthy lifestyle for fertility. Better designed studies, with larger sample sizes using conventional semen analysis with sperm DNA analysis methods, should be planned to identify the possible effects of lifestyle factors on semen quality.

Melatonin and Caffeine Supplementation Used, Respectively, as Protective and Stimulating Agents in the Cryopreservation of Human Sperm Improves Survival, Viability, and Motility after Thawing compared to Traditional TEST-Yolk Buffer

Cryopreservation processes can damage spermatozoa and impair structural and functional cell characteristics. Plasma, nuclear membranes, and cellular organelles can suffer from the freeze and thaw process. This study evaluates the protective and stimulant effect of melatonin and caffeine supplementation on the functional characteristics of human spermatozoa before and after freezing. Thirty seminal samples from normozoospermic men aged 19–45 years old collected between October 2012 and May 2017 were included. Semen samples were supplemented with either 2 mM melatonin (MEL) prior to cryopreservation, 2 mM caffeine (CAF) in postthaw, or CAF and MEL (CM) in precryopreservation and postthaw, respectively. Kinetics and seminal parameters, mitochondrial activity, DNA fragmentation, and reactive oxygen species (ROS) levels were analyzed before and after cryopreservation. A significant reduction in sperm concentration, total and progressive motility, sperm kinetics, and mitochondrial activity, as well as a significant increase in DNA fragmentation and ROS production in postthaw samples compared to fresh samples, was identified. After administration of a caffeine and/or melatonin supplement, there was a significant increase in progressive motility in the CAF (p = 0.005) and CM (p = 0.048) groups, as well as mitochondrial activity in the CM group (p < 0.05). Cryopreservation has negative effects on overall sperm quality and increases ROS production. A combination of caffeine and melatonin in prefreeze and postthaw sperm samples has proven to be a very effective and simple way to improve semen quality. This will be particularly useful for initial low-quality semen samples, those which suffer the most from the freezing/thawing process.

Substance Abuse and Male Hypogonadism

Progressive deterioration of male reproductive function is occurring in Western countries. Environmental factors and unhealthy lifestyles have been implicated in the decline of testosterone levels and sperm production observed in the last fifty years. Among unhealthy lifestyles, substance and drug abuse is a recognized cause of possible alterations of steroidogenesis and spermatogenesis. Alcohol, opioids and anabolic-androgenic steroids are capable to reduce testosterone production in male interfering with testicular and/or hypothalamic-pituitary function. Other substances such as nicotine, cannabis, and amphetamines alter spermatogenesis inducing oxidative stress and subsequent apoptosis in testicular tissue. Substance and drug abuse is a potentially reversible cause of hypogonadism, defined as the failure of the testis to produce physiological concentrations of testosterone and/or a normal number of spermatozoa. The identification of the abuse is important because the withdrawal of substance intake can reverse the clinical syndrome. This review summarizes the most important clinical and experimental evidence on the effect of substance abuse on testosterone and sperm production.

The relationship between diet, energy balance and fertility in men

Research conducted in recent years provides more and more evidence that diet can have a significant impact on male fertility. The aim of the study was to analyze the relationship between diet, energy balance and fertility in men. A comprehensive literature search of published studies in various languages, was carried out in electronic databases. The direct analysis included 96 works published between 2008 and 2018, including 12 randomized controlled trials and 23 systematic reviews and meta-analyses. A strong adherence to a healthy dietary pattern is positively correlated with total sperm count, progressive motility and total motile sperm count (all p < 0.05). However, attention is drawn to the fact that foods that are considered "healthy" can sometimes contain a significant amount of pollution, which negatively affect the semen parameters. An adequate intake of antioxidants or their supplementation have been quite effective in the prevention and treatment of male infertility. The improvement of pregnancy rate after antioxidant therapy ranged in various studies from 11% to 41%. An important problem, however, may be choosing the right dose of the supplement or finding an appropriate combination of antioxidants that may be more effective than any single antioxidant. The normalization of men's body weight is beneficial for the quality of sperm and the concentration of male reproductive hormones. Further, long-term studies require the assessment of the impact of drastic weight loss after bariatric surgery on male fertility.

Lifestyle causes of male infertility

Objective

To examine the potential effects of lifestyle factors on male reproductive health. Evidence of a global decline in human sperm quality over recent decades has been accumulating. Environmental, occupational, and modifiable lifestyle factors may contribute to this decline. This review focuses on key lifestyle factors that are associated with male infertility such as smoking cigarettes, alcohol intake, use of illicit drugs, obesity, psychological stress, advanced paternal age, dietary practices, and coffee consumption. Other factors such as testicular heat stress, intense cycling training, lack of sleep and exposure to electromagnetic radiation from mobile phone use are briefly discussed.

Materials and method

A comprehensive literature search was performed to identify and synthesise all relevant information, mainly from within the last decade, on the major lifestyle factors associated with male infertility and semen quality. Database searches were limited to reports published in English only. A manual search of bibliographies of the reports retrieved was conducted to identify additional relevant articles.

Results

In all, 1012 articles were identified from the database search and after reviewing the titles and abstract of the reports, 104 articles met the inclusion criteria. Of these, 30 reports were excluded as the full-text could not be retrieved and the abstract did not have relevant data. The remaining 74 reports were reviewed for data on association between a particular lifestyle factor and male infertility and were included in the present review.

Conclusion

The major lifestyle factors discussed in the present review are amongst the multiple potential risk factors that could impair male fertility. However, their negative impact may well be mostly overcome by behaviour modification and better lifestyle choices. Greater awareness and recognition of the possible impact of these lifestyle factors are important amongst couples seeking conception.

Dietary patterns, foods and nutrients in male fertility parameters and fecundability: a systematic review of observational studies

BACKGROUND

Infertility is a global public health issue, affecting 15% of all couples of reproductive age. Male factors, including decreased semen quality, are responsible for ~25% of these cases. The dietary pattern, the components of the diet and nutrients have been studied as possible determinants of sperm function and/or fertility.

OBJECTIVE AND RATIONALE

Previous systematic reviews have been made of the few heterogeneous low-quality randomized clinical trials (RCTs) conducted in small samples of participants and investigating the effect of specific nutrients and nutritional supplements on male infertility. However, as yet there has been no systematic review of observational studies.

SEARCH METHODS

A comprehensive systematic review was made of the published literature, from the earliest available online indexing year to November 2016, in accordance with the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. We have included cross-sectional, case-control and prospective and retrospective studies in which fertile/infertile men were well defined (men with sperm disorders, sperm DNA damage, varicocele or idiopathic infertility). The primary outcomes were semen quality or fecundability. With the data extracted, we evaluated and scored the quality of the studies selected. We excluded RCTs, animal studies, review articles and low-quality studies.

OUTCOMES

A total of 1944 articles were identified, of which 35 were selected for qualitative analysis. Generally, the results indicated that healthy diets rich in some nutrients such as omega-3 fatty acids, some antioxidants (vitamin E, vitamin C, β-carotene, selenium, zinc, cryptoxanthin and lycopene), other vitamins (vitamin D and folate) and low in saturated fatty acids and trans-fatty acids were inversely associated with low semen quality parameters. Fish, shellfish and seafood, poultry, cereals, vegetables and fruits, low-fat dairy and skimmed milk were positively associated with several sperm quality parameters. However, diets rich in processed meat, soy foods, potatoes, full-fat dairy and total dairy products, cheese, coffee, alcohol, sugar-sweetened beverages and sweets have been detrimentally associated with the quality of semen in some studies. As far as fecundability is concerned, a high intake of alcohol, caffeine and red meat and processed meat by males has a negative influence on the chance of pregnancy or fertilization rates in their partners.

WIDER IMPLICATIONS

Male adherence to a healthy diet could improve semen quality and fecundability rates. Since observational studies may prove associations but not causation, the associations summarized in the present review need to be confirmed with large prospective cohort studies and especially with well-designed RCTs.

Coffee and caffeine intake and male infertility: a systematic review

BACKGROUND

Semen quality, a predictor of male fertility, has been suggested declining worldwide. Among other life style factors, male coffee/caffeine consumption was hypothesized to influence semen parameters, but also sperm DNA integrity. To summarize available evidence, we performed a systematic review of observational studies on the relation between coffee/caffeine intake and parameters of male fertility including sperm ploidy, sperm DNA integrity, semen quality and time to pregnancy.

METHODS

A systematic literature search was performed up to November 2016 (MEDLINE and EMBASE). We included all observational papers that reported the relation between male coffee/caffeine intake and reproductive outcomes: 1. semen parameters, 2. sperm DNA characteristics, 3. fecundability. All pertinent reports were retrieved and the relative reference lists were systematically searched in order to identify any potential additional studies that could be included.

RESULTS

We retrieved 28 papers reporting observational information on coffee/caffeine intake and reproductive outcomes. Overall, they included 19,967 men. 1. Semen parameters did not seem affected by caffeine intake, at least caffeine from coffee, tea and cocoa drinks, in most studies. Conversely, other contributions suggested a negative effect of cola-containing beverages and caffeine-containing soft drinks on semen volume, count and concentration. 2. As regards sperm DNA defects, caffeine intake seemed associated with aneuploidy and DNA breaks, but not with other markers of DNA damage. 3. Finally, male coffee drinking was associated to prolonged time to pregnancy in some, but not all, studies.

CONCLUSIONS

The literature suggests that caffeine intake, possibly through sperm DNA damage, may negatively affect male reproductive function. Evidence from epidemiological studies on semen parameters and fertility is however inconsistent and inconclusive. Well-designed studies with predefined criteria for semen analysis, subject selection, and life style habits definition, are essential to reach a consistent evidence on the effect of caffeine on semen parameters and male fertility.

Phosphodiesterase Inhibitors (PDE Inhibitors) and Male Reproduction

The nonspecific PDE inhibitors, particularly the methylxanthines: caffeine, pentoxifylline (PTX), and theophylline, are known to stimulate sperm motility in vitro and have been used to treat sperm prior to insemination. The in vivo effects are less dramatic. A beneficial effect of caffeine, which is a constituent of some medications, remains controversial. Very high doses of caffeine do have negative effects on fertility endpoints in men and experimental species. The specific PDE5 inhibitors, particularly sildenafil and tadalafil, are prescribed for erectile dysfunction, as well as pulmonary hypertension, lower urinary tract symptoms, and premature ejaculation. PDE5 is expressed throughout the contractile tissues of the male reproductive tract, generally increasing contractility. Some PDE5 inhibitors tend to increase circulating testosterone levels somewhat. For short-term exposure consistent with use prior to intercourse, there appears to be minimal effects on semen quality. Several large, randomized controlled trials (RCTs) in healthy men have not found adverse effects of long-term use of these drugs on semen quality. RCTs in infertile men have demonstrated a modest increase in semen quality. Animal studies at human equivalent doses (HED) have produced similar results in young males, but a study in aging male rats found progressive decreases in epididymal sperm quality accompanied by consistent degeneration of the seminal tubules suggesting that studies in older men might be warranted. A concerning study in mice found lower fertilization rates in males treated with HED of sildenafil and mated the next day to untreated females than for control males. Fertility studies in humans are needed.

Dose- and time-related effects of caffeine on the testis in immature male rats

We previously showed that prepubertal chronic caffeine exposure adversely affected the development of the testes in male rats. Here we investigated dose- and time-related effects of caffeine consumption on the testis throughout sexual maturation in prepubertal rats. A total of 80 male SD rats were randomly divided into four groups: controls and rats fed 20, 60, or 120 mg caffeine/kg/day, respectively, via gavage for 10, 20, 30, or 40 days. Preputial separation was monitored daily before the rats were sacrificed. Terminal blood samples were collected for hormone assay, and testes were grossly evaluated and weighed. One testis was processed for histological analysis, and the other was collected to isolate Leydig cells. Caffeine exposure significantly increased the relative weight of the testis in a dose-related manner after 30 days of exposure, whereas the absolute testis weight tended to decrease at the 120 mg dose of caffeine. The mean diameter of the seminiferous tubules and height of the germinal epithelium significantly decreased in the caffeine-fed groups after 40 days of caffeine exposure, which was accompanied by a reduced BrdU incorporation rate in germ cells. In addition, caffeine intake significantly reduced in vivo and ex vivo testosterone production in a dose-related manner. Our results demonstrate that caffeine exposure during sexual maturation alter the testicular microarchitecture and also slow germ cell proliferation even at the 20 mg dose level. Furthermore, caffeine may act directly on Leydig cells and interfere with testosterone production in a dose-related manner, consequently delaying onset of sexual maturation.

Implication of caffeine consumption and recovery on the reproductive functions of adult male Wistar rats

BACKGROUND

This study assessed the impact of caffeine consumption and recovery on reproductive functions and fertility of Wistar rats.

METHODS

Thirty-five adult male Wistar rats were divided into seven groups of five rats each. Group A (control) received distilled water (vehicle), while groups B, C, and D were treated orally with 10 mg/kg body weight (BW), 20 mg/kg BW, and 40 mg/kg BW caffeine, respectively, for 30 days. Groups E, F, and G were treated orally with 10 mg/kg BW, 20 mg/kg BW, and 40 mg/kg BW caffeine, respectively, for 30 days and then allowed to recover for another 30 days.

RESULTS

Caffeine caused a decrease in body weight, while recovery groups showed appreciable increase in body weight during recovery. Relative weight of seminal vesicle, prostate, and epididymis decreased dose dependently during treatment but increased during recovery. The liver and kidney weight increased during treatment but reduced during recovery. Sperm count was significantly decreased in both treated and recovery groups. Initial decrease in sperm viability and volume was appreciably reversed during recovery period. Serum level of testosterone increased at high doses, while serum luteinizing hormone (LH) and follicle-stimulating hormone (FSH) showed significant decrease. Histological sections of testis in treated groups showed mild congestion of the interstitial blood vessel and subcapsular congestion. However, there was no subcapsular congestion in the recovery groups. All rats in both treated and recovery groups had 100% fertilization success from fertility study.

CONCLUSIONS

Suggestively, caffeine treatment for 4 weeks could impair body, reproductive organs weight, sperm characteristics, LH/FSH level, and also testicular cyto-architecture. Effects appeared, however, reversible after caffeine withdrawal.

Caffeine and caffeinated beverage consumption and fecundability in a preconception cohort

Caffeine is an adenosine receptor antagonist that may influence fertility by affecting ovulation, menstrual characteristics, or sperm quality. We studied the association between female and male preconception caffeine intake and fecundability in a North American prospective cohort study of 2135 pregnancy planners. Frequency of caffeinated beverage intake was self-reported at baseline. Outcome data were updated every 8 weeks until reported pregnancy; censoring occurred at 12 months. Adjusted fecundability ratios (FR) and 95% confidence intervals (CI) were estimated using proportional probabilities regression. Total caffeine intake among males, but not females, was associated with fecundability (FR for ≥300 vs. <100mg/day caffeine among males=0.72, 95% CI=0.54-0.96), although the association was not monotonic. With respect to individual beverages, caffeinated tea intake was associated with slight reductions in fecundability among females, and caffeinated soda and energy drink intake were associated with reduced fecundability among males.

Sperm DNA damage-the effect of stress and everyday life factors

The clinical significance of sperm DNA damage lies in its association with natural conception rates and also might have a serious consequence on developmental outcome of the newborn. The aim of the present study is to determine whether stress and everyday life factors are associated with sperm DNA damage in adult men. The study population consisted of 286 men who attended the infertility clinic for diagnostic purposes and who had normal semen concentration of 20-300 m ml(-1) or with slight oligozoospermia (semen concentration of 15-20 m ml(-1)) (WHO, 1999). Participants were interviewed and provided a semen sample. The sperm chromatin structure assay was assessed using flow cytometry. In the present study, we found evidence for a relationship between sperm DNA damage parameters and everyday life factors. High and medium level of occupational stress and age increase DNA fragmentation index (P=0.03, P=0.004 and P=0.03, respectively). Other lifestyle factors that were positively associated with percentage of immature sperms (high DNA stainability index) included: obesity and cell phone use for more than 10 years (P=0.02 and P=0.04, respectively). Our findings indicate that stress and lifestyle factor may affect sperm DNA damage. Data from the present study showed a significant effect of age, obesity, mobile phone radiation and occupational stress on sperm DNA damage. As DNA fragmentation represents an extremely important parameter indicative of infertility and potential outcome of assisted reproduction treatment, and most of the lifestyle factors are easily modifiable, the information about factors that may affect DNA damage are important.

High doses of caffeine reduce in vivo osteogenic activity in prepubertal rats

Caffeine adversely affects endochondral ossification during fetal skeletal growth, and results in increased incidence of delayed and abnormal fetal skeletal development. Chronic caffeine intake also decreases growth hormone secretion. Thus, it is conceivable that caffeine may disrupt bone growth during the peripubertal period. This study aimed to investigate the impact of high-caffeine consumption on bone growth throughout puberty. A total of 51 male rats (21 days old) were divided randomly into three groups: a control group and two groups fed caffeine via gavage with 120 and 180 mg kg(-1)  day(-1) for 4 weeks. After death, the final length and weight of leg bones were measured, and the tibia processed for histomorphometric analysis. Caffeine caused a significant decrease in body mass gain. This was accompanied with proportional decreases in lean body mass and body fat. In addition, bone mass and osteogenic activity in vivo were assessed using dual-energy X-ray absorptiometry and (18) F-NaF positron emission tomography. The results showed significant decreases of bone mass and in vivo osteogenic activity in the caffeine-fed groups. Rats fed with caffeine showed a significantly shorter and lighter tibia and femur and the vertebral column compared with controls. In addition, caffeine does not increase the width of the growth plates (GPs), it slows the rate at which the GP closes due to a slower rate of growth. These results demonstrated that caffeine altered osteogenic activity, leading to delayed peripubertal longitudinal bone growth and maturation. Given that osteogenic cells undergo dynamic changes in metabolic activity and that the pubertal growth spurt is mainly stimulated by growth hormone/insulin-like growth factor-1 and sex steroids during pubertal development, caffeine could suppress ossification by interfering with both physiological changes in hormonal secretion and osteogenic activity during this critical period. Further study will be needed to investigate the cellular/molecular mechanism by which caffeine affects osteogenesis using in vitro experimental models.

In vitro fertilization embryo development from caffeine-treated murine sperm

Purpose

To evaluate the effect of long-term caffeine administration on murine sperm and subsequent in vitro fertilization (IVF).

Methods

Male mice were injected with various doses (0, 0.2 and 1.0 mg/mouse/day) of caffeine for 1 month. After sperm collection, the IVF rate and embryo development to the blastocyst stage were evaluated.

Results

The mean body weight significantly decreased in the 1.0 mg/day treatment group compared to the control group (P < 0.01). Testicular weight and histological features did not differ, and total blood testosterone was no different in spite of the difference between 0.2 and 1.0 mg/day of caffeine. The IVF rate differed significantly between the control group [100/105 (95.2 %)] and 0.2 mg/day group [106/121 (87.6 %)] (P < 0.05). Furthermore, blastocyst formation was significantly and dose-dependently lower with higher caffeine levels: control group: 85/100 (85.0 %); 0.2 mg/day group: 84/106 (79.2 %) (P < 0.05); 1.0 mg/day group: 64/102 (62.7 %) (P < 0.001).

Conclusions

Caffeine treatment affected body weight of male mice. However, testicular weight, histological features and total blood testosterone concentration were not statistically different. In addition, following IVF using sperm from these mice, blastocyst formation decreased in a dose-dependent manner. These findings suggest that embryo development from oocytes fertilized with sperm from caffeine-administered male mice is negatively affected.

High Doses of Caffeine during the Peripubertal Period in the Rat Impair the Growth and Function of the Testis

Prenatal caffeine exposure adversely affects the development of the reproductive organs of male rat offspring. Thus, it is conceivable that peripubertal caffeine exposure would also influence physiologic gonadal changes and function during this critical period for sexual maturation. This study investigated the impact of high doses of caffeine on the testes of prepubertal male rats. A total of 45 immature male rats were divided randomly into three groups: a control group and 2 groups fed 120 and 180 mg/kg/day of caffeine, respectively, via the stomach for 4 weeks. Caffeine caused a significant decrease in body weight gain, accompanied by proportional decreases in lean body mass and body fat. The caffeine-fed animals had smaller and lighter testes than those of the control that were accompanied by negative influences on the histologic parameters of the testes. In addition, stimulated-testosterone ex vivo production was reduced in Leydig cells retrieved from the caffeine-fed animals. Our results demonstrate that peripubertal caffeine consumption can interfere with the maturation and function of the testis, possibly by interrupting endogenous testosterone secretion and reducing the sensitivity of Leydig cells to gonadotrophic stimulation. In addition, we confirmed that pubertal administration of caffeine reduced testis growth and altered testis histomorphology.

Sugar-sweetened beverage intake in relation to semen quality and reproductive hormone levels in young men

STUDY QUESTION

Is consumption of sugar-sweetened beverages (SSB) associated with semen quality?

SUMMARY ANSWER

Higher consumption of SSB was associated with lower sperm motility among healthy, young men.

WHAT IS KNOWN ALREADY

The existing literature on the potential role of SSBs on male reproductive function is scarce and primarily focused on the relation between caffeinated beverages and semen quality. However, a rodent model suggests that SSBs may hamper male fertility.

STUDY DESIGN, SIZE, DURATION

The Rochester Young Men's Study; a cross-sectional study of 189 healthy young men carried out at the University of Rochester during 2009-2010.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Men aged 18-22 years provided semen and blood samples, underwent a physical examination and completed a previously validated food frequency questionnaire (FFQ). Linear regression was used to analyze the association of SSBs with sperm parameters and reproductive hormone levels while adjusting for potential confounders.

MAIN RESULTS AND THE ROLE OF CHANCE

SSB intake was inversely related to progressive sperm motility. Men in the highest quartile of SSB intake (≥1.3 serving/day) had 9.8 (95% CI: 1.9,17.8) percentage units lower progressive sperm motility than men in the lowest quartile of intake (<0.2 serving/day) (P, trend = 0.03). This association was stronger among lean men (P, trend = 0.005) but absent among overweight or obese men (P, trend = 0.98). SSB intake was unrelated to other semen quality parameters or reproductive hormones levels.

LIMITATIONS, REASONS FOR CAUTION

As in all cross-sectional studies, causal inference is limited. An additional problem is that only single semen sample was obtained from each subject.

WIDER IMPLICATIONS OF THE FINDINGS

To our knowledge, this is the first report on the relation between SSB intake and low semen quality beyond the contribution of caffeinated beverages. While our findings are in agreement with recent experimental data in rodents, more studies are required to draw conclusions on the relation of SSB with semen quality or male infertility.

STUDY FUNDING/COMPETING INTEREST(S)

Supported by the European Union Seventh Framework Program (Environment), 'Developmental Effects of Environment on Reproductive Health' (DEER) grant 212844. Grant P30 DK046200 and Ruth L. Kirschstein National Research Service Award T32 DK007703-16 and T32HD060454 from the National Institutes of Health. None of the authors has any conflicts of interest to declare.

Effect of long-term caffeine administration to mice on in vitro fertilization and embryo development using oocytes

PURPOSE

To evaluate the effect of long-term caffeine administration to mice on in vitro fertilization (IVF) of oocytes.

METHODS

Mice were injected with different dosages (0, 0.1, and 1.0 mg/mouse/converted day) of caffeine for one month. Subsequently, the fertilization rate and embryo development to blastocyst stage were evaluated in IVF using oocytes from the mice.

RESULTS

The retrieved average oocyte rate was significantly lower (27.4) in mice injected with 1.0 mg caffeine than in the control group (36.5; P < 0.05); the fertilization rate was significantly different between the 0 mg (317/401; 79.1 %) and 1.0 mg group (199/301; 66.1 %) (P < 0.05). At 96 h after insemination, the blastocyst formation rate was significantly decreased in the 1.0 mg group (94/199; 47.2 %) compared with the control (0 mg) group (237/317; 74.8 %) and 0.1 mg group (226/323; 70 %) (P < 0.05). When 1.0 mg caffeine was administered for two weeks, embryo development was significantly impacted.

CONCLUSIONS

Our findings suggest that caffeine administration negatively impacts oocytogenesis and embryonic development after IVF.

No harmful effect of different Coca-cola beverages after 6 months of intake on rat testes

Our laboratory recently reported that a 3-month exposure of rats to cola-like beverages induced sex hormone changes. The aim of the study was to investigate the effects of various types of Coca-cola intake with different composition for 6 months on oxidative status in testes and testosterone in adult male rats. Fifty adult male Wistar rats were divided into control group drinking water, and groups drinking different Coca-cola beverages (regular Coca-cola, Coca-cola caffeine-free, Coca-cola Light and Coca-cola Zero). Oxidative and carbonyl stress markers were measured in the testicular tissue to assess oxidative status together with testicular and plasma testosterone. StAR expression in testes as a marker of steroidogenesis was quantified. No significant differences were found between the groups in any of the measured parameters. In conclusion, oxidative and carbonyl stress in testicular tissue were not influenced by drinking any type of Coca-cola. Additionally, testosterone in testes and in plasma, as well as testicular StAR expression were comparable among the groups.

Maternal caffeine consumption has irreversible effects on reproductive parameters and fertility in male offspring rats

OBJECTIVE

Concerns are growing about the decrease in male reproductive health. Caffeine is one of the popular nutrients that has been implicated as a risk factor for infertility. In the present study, we examined whether in utero and lactational exposure to caffeine affects the reproductive function of the offspring of rats.

METHODS

Pregnant rats received caffeine via drinking water during gestation (26 and 45 mg/kg) and lactation (25 and 35 mg/kg). Body and reproductive organ weight, seminiferous tubule diameter, germinal epithelium height, sperm parameters, fertility rate, number of implantations, and testosterone level of the offspring were assessed from birth to adulthood.

RESULTS

Significant dose-related decreases were observed in the body and reproductive organ weight, seminiferous tubule diameter, and germinal epithelium height of the offspring. Sperm density had declined significantly in offspring of the low-dose and high-dose groups, by 8.81% and 19.97%, respectively, by postnatal day 150. The number of viable fetuses had decreased significantly in females mated with male offspring of the high-dose group at postnatal days 60, 90, 120, and 150. There were also significant reductions in testosterone levels of high-dose group offspring from birth to postnatal day 150.

CONCLUSION

It is concluded that maternal caffeine consumption impairs gonadal development and has long-term adverse effects on the reproductive efficiency of male offspring rats.

Effect of maternal coffee, smoking and drinking behavior on adult son's semen quality: prospective evidence from the Child Health and Development Studies

Fetal exposure to caffeine is associated with adverse pregnancy outcomes. Animal and human studies suggest that caffeine may have effects on the developing reproductive system. Here we report on mothers' smoking, coffee and alcohol use, recorded during pregnancy, and semen quality in sons in the age group of 38-47 years. Subjects were a subset of the Child Health and Development Studies, a pregnancy cohort enrolled between 1959 and 1967 in the Kaiser Foundation Health Plan near Oakland, California. In 2005, adult sons participated in a follow-up study (n = 338) and semen samples were donated by 196 participants. Samples were analyzed for sperm concentration, motility and morphology according to the National Cooperative Reproductive Medicine Network (Fertile Male Study) Protocol. Mean sperm concentration was reduced by approximately 16 million sperms for sons with high prenatal exposure (5 cups of maternal coffee use per day) compared with unexposed sons (P-value for decreasing trend = 0.09), which translates to a proportionate reduction of 25%. Mean percent motile sperm decreased by approximately 7 points (P-value = 0.04), a proportionate decline of 13%, and mean percent sperm with normal morphology decreased by approximately 2 points (P-value = 0.01), a proportionate decline of 25%. Maternal cigarette and alcohol use were not associated with son's semen quality. Adjusting for son's contemporary coffee, alcohol and cigarette use did not explain the maternal associations. Findings for son's coffee intake and father's prenatal coffee, cigarette and alcohol use were non-significant and inconclusive. These results contribute to the evidence that maternal coffee use during pregnancy may impair the reproductive development of the male fetus.

Methylxanthines and reproduction

Reproduction is the process by which organisms create descendants. In human reproduction, two kinds of sex cells, or gametes, are involved. Sperm, the male gamete, and egg egg , or ovum ovum Vedi egg , the female gamete, must meet in the female reproductive system to create a new individual and both the female and the male reproductive systems are essential to the occurrence of reproduction. Scientific reports dealing with the effects of methylxanthines on reproduction are mostly centred on the use of these compounds as phosphodiesterase inhibitors that, by maintaining high intracellular levels of cyclic AMP (cAMP) cyclic AMP , will affect the gametes differently. High cAMP levels will sustain sperm sperm maturation while they hold the oocytes in mitotic arrest. Caffeine caffeine , being the methylxanthine most widely consumed by every segment of the population, has been the subject of greatest interest among health professionals and researchers. Conflicting results still seem to characterize the association between male/female caffeine caffeine consumption in adult life and semen quality/fertility fertility , although moderate daily caffeine consumption of levels up to 400-450 mg/day (5.7-6.4 mg/kg/day in a 70-kg adult) do not seem to be associated with adverse effects, i.e. general toxicity, effects on bone status and calcium balance, cardiovascular effects, behavioural changes, increased incidence of cancer, or effects on male fertility. A clear stimulation of egg-laying by the coffee leaf pest Leucoptera coffeella was recently reported, providing support for the hypothesis that caffeine, in a dose-dependent way, in insects stimulates egg-laying, thus leading to the death of coffee trees.

A review of the epidemiologic evidence concerning the reproductive health effects of caffeine consumption: a 2000-2009 update

This review of human studies of caffeine and reproductive health published between January 2000 and December 2009 serves to update the comprehensive review published by Leviton and Cowan (2002). The adverse reproductive outcomes addressed in this review include: (1) measures of subfecundity; (2) spontaneous abortion; (3) fetal death; (4) preterm birth; (5) congenital malformations; and (6) fetal growth restriction. Methodologic challenges and considerations relevant to investigations of each reproductive endpoint are summarized, followed by a brief critical review of each study. The evidence for an effect of caffeine on reproductive health and fetal development is limited by the inability to rule out plausible alternative explanations for the observed associations, namely confounding by pregnancy symptoms and smoking, and by exposure measurement error. Because of these limitations, the weight of evidence does not support a positive relationship between caffeine consumption and adverse reproductive or perinatal outcomes.

Caffeine intake and semen quality in a population of 2,554 young Danish men

The authors examined the association between semen quality and caffeine intake among 2,554 young Danish men recruited when they were examined to determine their fitness for military service in 2001-2005. The men delivered a semen sample and answered a questionnaire including information about caffeine intake from various sources, from which total caffeine intake was calculated. Moderate caffeine and cola intakes (101-800 mg/day and < or =14 0.5-L bottles of cola/week) compared with low intake (< or =100 mg/day, no cola intake) were not associated with semen quality. High cola (>14 0.5-L bottles/week) and/or caffeine (>800 mg/day) intake was associated with reduced sperm concentration and total sperm count, although only significant for cola. High-intake cola drinkers had an adjusted sperm concentration and total sperm count of 40 mill/mL (95% confidence interval (CI): 32, 51) and 121 mill (95% CI: 92, 160), respectively, compared with 56 mill/mL (95% CI: 50, 64) and 181 mill (95% CI: 156, 210) in non-cola-drinkers, which could not be attributed to the caffeine they consumed because it was <140 mg/day. Therefore, the authors cannot exclude the possibility of a threshold above which cola, and possibly caffeine, negatively affects semen quality. Alternatively, the less healthy lifestyle of these men may explain these findings.