The importance of folate, zinc and antioxidants in the pathogenesis and prevention of subfertility

Current treatments of subfertile couples are usually empiric, as the true cause of subfertility often remains unknown. Therefore, we outline the role of nutritional and biochemical factors in reproduction and subfertility. A literature search was performed using MEDLINE, Science Direct and bibliographies of published work with both positive and negative results. The studies showed that folate has a role in spermatogenesis. In female reproduction, folate is also important for oocyte quality and maturation, implantation, placentation, fetal growth and organ development. Zinc has also been implicated in testicular development, sperm maturation and testosterone synthesis. In females, zinc plays a role in sexual development, ovulation and the menstrual cycle. Both folate and zinc have antioxidant properties that counteract reactive oxygen species (ROS). Thiols, such as glutathione, balance the levels of ROS produced by spermatozoa and influence DNA compaction and the stability and motility of spermatozoa. Oocyte maturation, ovulation, luteolysis and follicle atresia are also affected by ROS. After fertilization, glutathione is important for sperm nucleus decondensation and pronucleus formation. Folate, zinc, ROS and thiols affect apoptosis, which is important for sperm release, regulation of follicle atresia, degeneration of the corpus luteum and endometrial shedding. Therefore, the concentrations of these nutrients may have substantial effects on reproduction. In conclusion, nutritional and biochemical factors affect biological processes in male and female reproduction. Further research should identify pathways that may lead to improvements in care and treatment of subfertility.     

Decreased methylene tetrahydrofolate reductase activity due to the 677C→T mutation in families with spina bifida offspring

 Periconceptional folate intake reduces both the occurrence and recurrence risk of neural tube defects. Plasma homocysteine levels can be elevated in mothers of a child with a neural tube defect, suggesting a dysfunctional folate metabolism. Very recently we showed that a common 677C→T mutation in the 5,10-methylene tetrahydrofolate reductase gene, causing thermolability of the enzyme, is a risk factor for spina bifida offspring. Restriction enzyme analysis of the genomic 5,10-methylene tetrahydrofolate reductase polymerase chain reaction fragment revealed a significantly higher prevalence of a +/+ genotype among spina bifida patients and their mothers. The risk for spina bifida offspring is the strongest if both the mother and her child have the mutation in the homozygous state. Enzymatic analysis showed that homozygosity for the 677C→T mutation causes a decreased 5,10-methylene tetrahydrofolate reductase activity, resulting in elevated plasma homocysteine and red blood cell folate levels and lowered plasma folate and cysteine values. This extended study demonstrates that a nucleotide substitution in the coding region of 5,10-methylene tetrahydrofolate reductase, resulting in reduced activity and an impaired homocysteine and folate metabolism, is a genetic risk factor for spina bifida. Received: 24 May 1996 / Accepted: 14 August 1996     

Early pregnancy exposure to antihistamines and risk of congenital heart defects: results of two case–control studies

We aimed to study the association between use of antihistamines in early pregnancy and congenital heart defects (CHD) in the offspring. Design: Two case–control studies. Setting: HAVEN study, Erasmus MC, University Medical Centre, Rotterdam, and Eurocat Northern Netherlands (NNL), University Medical Center Groningen, Groningen, the Netherlands. We studied 361 children with CHD and 410 controls without congenital malformations from the HAVEN study and replicated the analyses in 445 children with CHD and 530 controls from the Eurocat NNL registry. Information about antihistamine use in early pregnancy and potential confounders was obtained from questionnaires postpartum. We calculated the association between antihistamines and CHD risk by multivariable logistic regression analysis. Main outcome measures: Odds ratios (OR) with 95 % confidence intervals (CI). In the HAVEN study, 25 of 771 mothers used antihistamines that were associated with an increased CHD risk (OR 3.0, 95 % CI 1.2–7.3), particularly atrioventricular septal defects (AVSD) (OR 5.1, 95 % CI 1.3–20.5) and perimembranous ventricular septal defects (pVSD) (OR 5.1, 95 % CI 1.8–14.4). Mothers with severe nausea who did not use antihistamines had a reduced risk (OR 0.7, 95 % CI 0.5–0.98), whereas nauseous mothers using antihistamines showed an almost fivefold increased risk of pVSD (OR 4.8, 95 % CI 1.1–21.8). The association between antihistamines and AVSD was confirmed in the Eurocat cohort (OR 3.5, 95 % CI 1.4–8.7), but we could not replicate the association with overall CHD risk. We found a positive association between antihistamine use in early pregnancy and CHD risk, particularly AVSD, which seemed to be independent of nausea/vomiting.     

A longitudinal study of antioxidant status during uncomplicated and hypertensive pregnancies

BACKGROUND: To study the possible involvement of an (im)balance between oxidants and antioxidants in pre-eclampsia concentrations of intra- and extracellular blood antioxidants in women with uncomplicated and hypertensive pregnancies, they were studied preconceptionally and throughout pregnancy. METHODS: In uncomplicated pregnancies (n = 19) and hypertensive pregnancies (n = 6) concentrations of whole blood and plasma thiols, plasma vitamins/E and C, hemoglobin, and hematocrit were assessed at preconception, 6, 10, 20, and 37 weeks of gestational age, as well as six weeks postpartum. A repeated mixed model was used for statistical analysis. RESULTS: Vitamin C and most whole blood and plasma thiol concentrations decreased during pregnancy, while vitamin E, whole blood oxidized cysteinyl-glycine and the ratio of free to oxidized homocysteine revealed a linear increase during pregnancy. Postpartum plasma cysteine and vitamin C levels and the ratio of free to oxidized levels of cysteine, cysteinyl-glycine, and glutathione were significantly (p <0.05) lower as compared to preconceptional levels, whereas whole blood oxidized cysteine, cysteinyl-glycine and glutathione levels, and whole blood and plasma homocysteine levels were significantly (p <0.05) higher six weeks after delivery. Plasma cysteine and homocysteine, and whole blood oxidized cysteine and homocysteine levels were significantly (p <0.05) higher at 37 weeks of gestational age in the hypertensive group compared to those in the uncomplicated group. There were no other differences between the hypertensive and uncomplicated groups. CONCLUSION: In normal pregnancy there seems a balance between antioxidant and oxidant concentrations despite modest oxidative stress. In mildly hypertensive pregnancies a marginal imbalance may occur.     

Seminal plasma cobalamin significantly correlates with sperm concentration in men undergoing IVF or ICSI procedures

Mild hyperhomocysteinemia is caused by B vitamin deficiencies. We hypothesize that these biochemical derangements detrimentally affect spermatogenesis. Therefore, the aim of this study was to investigate the folate, cobalamin, pyridoxine, and homocysteine concentrations in blood and seminal plasma and the associations between these biomarkers and semen parameters in men participating in an in vitro fertilization or intracytoplasmic sperm injection program. From 73 men (median age [range]: 37 years [28-53]), blood and semen samples were obtained for the determination of serum and red blood cell (RBC) folate, serum total cobalamin, whole-blood pyridoxal-5'-phosphate, plasma total homocysteine (tHcy), and serum total testosterone. Semen analysis included sperm concentration, motility, and morphology according to World Health Organization criteria. The B vitamins and tHcy concentrations were significantly correlated in blood but not in seminal plasma. The serum and RBC folate concentrations were significantly correlated also with the total folate concentration in seminal plasma (r = .44; P < .001 and r = .39; P < .001, respectively). Likewise, the total cobalamin concentration in serum and seminal plasma was significantly correlated (r = .55; P = .001). Of interest is that the total cobalamin concentration in seminal plasma was significantly correlated with the sperm concentration (r = .42; P < .001). This is in contrast to the absence of significant associations between the other vitamins and tHcy in blood and seminal plasma and any of the semen parameters. These findings suggest that folate and cobalamin are transferred from the blood to the male reproductive organs and emphasize the role of cobalamin in spermatogenesis in human.     

New Ultrasound Measurements to Bridge the Gap between Prenatal and Neonatal Brain Growth Assessment

BACKGROUND AND PURPOSE:Most ultrasound markers for monitoring brain growth can only be used in either the prenatal or the postnatal period. We investigated whether corpus callosum length and corpus callosum–fastigium length could be used as markers for both prenatal and postnatal brain growth.MATERIALS AND METHODS:A 3D ultrasound study embedded in the prospective Rotterdam Periconception Cohort was performed at 22, 26 and 32 weeks'' gestational age in fetuses with fetal growth restriction, congenital heart defects, and controls. Postnatally, cranial ultrasound was performed at 42 weeks'' postmenstrual age. First, reliability was evaluated. Second, associations between prenatal and postnatal corpus callosum and corpus callosum–fastigium length were investigated. Third, we created reference curves and compared corpus callosum and corpus callosum–fastigium length growth trajectories of controls with growth trajectories of fetuses with fetal growth retardation and congenital heart defects.RESULTS:We included 199 fetuses; 22 with fetal growth retardation, 20 with congenital heart defects, and 157 controls. Reliability of both measurements was excellent (intraclass correlation coefficient ≥ 0.97). Corpus callosum growth trajectories were significantly decreased in fetuses with fetal growth restriction and congenital heart defects (β = −2.295; 95% CI, −3.320–1.270; P < .01; β = −1.267; 95% CI, −0.972–0.562; P < .01, respectively) compared with growth trajectories of controls. Corpus callosum–fastigium growth trajectories were decreased in fetuses with fetal growth restriction (β = −1.295; 95% CI, −2.595–0.003; P = .05).CONCLUSIONS:Corpus callosum and corpus callosum–fastigium length may serve as reliable markers for monitoring brain growth from the prenatal into the postnatal period. The clinical applicability of these markers was established by the significantly different corpus callosum and corpus callosum–fastigium growth trajectories in fetuses at risk for abnormal brain growth compared with those of controls.

In preterm infants and those small-for-gestational age, brain growth is an important predictor of neurodevelopmental outcome.^1–4 Although prenatal growth often predicts postnatal growth, there is a traditional division between fetal and neonatal growth charts.⁵ This is mainly due to the lack of consistent measures of brain growth that can be used in both the prenatal and postnatal periods.Markers of brain growth that can theoretically be used in both the prenatal and postnatal periods include head circumference and a few ultrasound (US) and MR imaging measures. Head circumference measured postnatally, however, lacks precision and does not correspond well with neurodevelopmental outcome.^6,7 Prenatal and postnatal US markers are largely based on individual brain structures, only reflecting growth of a specific part of the brain.^8–12 Moreover, these brain structures are not measured consistently during the prenatal and postnatal periods due to the absence of corresponding standard US planes. Although MR imaging provides more precise measures of brain growth, volume, and development, this technique is expensive and therefore not suitable for serial measurements.Recently, we demonstrated that corpus callosum–fastigium (CCF) length is a reliable bedside-available US marker that can be used to monitor brain growth in preterm infants during neonatal intensive care unit stays.¹³ CCF length is considered a composite marker of diencephalon and mesencephalon size and thereby adds information to the more widely used corpus callosum (CC) length.¹³ We hypothesized that these 2 cranial ultrasound measures are feasible for use during prenatal US examinations. Thereby, these markers would provide a continuum for monitoring brain growth, bridging the period before and after birth.Our main aim was to investigate whether CC and CCF lengths can be used as reliable US markers for monitoring fetal and neonatal brain growth. First, we assessed the reliability of the measurements. Second, we created reference curves from 22 to 42 weeks'' gestational age (GA) by combining fetal and neonatal measurements. Finally, as a first step to evaluate the clinical applicability of these US markers, we investigated CC and CCF growth trajectories in fetuses at risk of abnormal brain growth and compared them with those of control fetuses.     

Does folic acid and zinc sulphate intervention affect endocrine parameters and sperm characteristics in men?

We evaluated pre- and post-intervention endocrine and semen parameters in a double-blind, placebo-controlled intervention study to investigate the underlying mechanism of increased sperm concentration after folic acid and zinc sulphate intervention. A total of 47 fertile and 40 subfertile males participated in a 26-week intervention study consisting of a daily treatment with folic acid (5 mg/day) and zinc sulphate (66 mg/day), or placebo. Pre- and post-intervention semen parameters, serum folate, zinc, follicle-stimulating hormone (FSH), testosterone and inhibin B concentrations were measured. The results indicated that intervention treatment significantly increased sperm concentration in subfertile males. Other semen and endocrine parameters were not affected by intervention treatment. At baseline, positive correlations were found between serum zinc and sperm concentration, motility and inhibin B. Serum zinc and FSH were inversely correlated. As (already) well known from previous research, inhibin B positively correlated with sperm concentration, motility and morphology, and was inversely correlated with FSH. The latter was positively correlated with testosterone. In addition, testosterone and inhibin B were inversely correlated. After intervention, the correlations with zinc disappeared. We conclude that the increase in sperm concentration after folic acid and zinc sulphate intervention is not the result of alterations in FSH, testosterone or inhibin B concentrations. Although zinc and folate have several effects on spermatogenesis, the underlying mechanisms involved are not clear.     

Effects of folic acid and zinc sulfate on male factor subfertility: a double-blind, randomized, placebo-controlled trial

OBJECTIVE: To study the effects of folic acid and zinc sulfate treatment on semen variables in fertile and subfertile men. DESIGN: Double-blind, placebo-controlled interventional study. SETTING: Two outpatient fertility clinics and nine midwifery practices in The Netherlands. PARTICIPANT(S): One hundred eight fertile and 103 subfertile men. INTERVENTION(S): Both groups were randomly assigned to receive one of four treatments for 26 weeks: folic acid and placebo, zinc sulfate and placebo, zinc sulfate and folic acid, and two placebos. Folic acid was given at a daily dose of 5 mg, and zinc sulfate was given at a daily dose of 66 mg. MAIN OUTCOME MEASURE(S): Before and after treatment, standardized semen and blood samples were obtained for determinations of sperm concentration, motility, and morphology according to World Health Organization guidelines; semen morphology according to strict criteria; and blood folate and zinc concentrations. Effects of the four interventions were evaluated separately in subfertile and fertile men. RESULT(S): Subfertile men demonstrated a significant 74% increase in total normal sperm count and a minor increase of 4% abnormal spermatozoa. A similar trend was observed in fertile men. Pre-intervention concentrations of folate and zinc in blood and seminal plasma did not significantly differ between fertile and subfertile men. CONCLUSION(S): Total normal sperm count increases after combined zinc sulfate and folic acid treatment in both subfertile and fertile men. Although the beneficial effect on fertility remains to be established, this finding opens avenues of future fertility research and treatment and may affect public health.