Dietary fatty acid intakes and asthenozoospermia: a case-control study Ghazaleh Eslamian, M.Sc.,a Naser Amirjannati, M.D.,b Bahram Rashidkhani, M.D., Ph.D.,c Mohammad-Reza Sadeghi, Ph.D.,b Ahmad-Reza Baghestani, Ph.D.,d and Azita Hekmatdoost, M.D., Ph.D.e a Students' Research Committee, c Department of Community Nutrition, and e Department of Clinical Nutrition and Dietetics, Faculty of Nutrition and Food Technology, National Nutrition and Food Technology, Research Institute, and d Department of Biostatistics, Faculty of Paramedical Sciences, Shahid Beheshti University of Medical Sciences; and b Department of Andrology and Embryology, Reproductive Biotechnology Research Center, Avicenna Research Institute, Academic Center for Education, Culture and Research (ACECR), Tehran, Iran
Objective: To investigate the association between dietary fatty acids intakes and asthenozoospermia. Design: Case-control study. Setting: Infertility clinics. Patient(s): A total of 107 men with incident asthenozoospermia and 235 age-matched controls. Intervention(s): None. Main Outcome Measure(s): Assessments of dietary intakes, semen quality, anthropometry, endocrine parameters, and demographic information. Result(s): According to the fully adjusted model, being in the highest tertile of total saturated fatty acids (odds ratio [OR] ¼ 1.85, 95% confidence interval [CI] 1.24–2.96), total trans-fatty acids (OR ¼ 2.53, 95% CI 1.54–3.92), palmitic acid (OR ¼ 1.90, 95% CI 1.26–2.74), and stearic acid (OR ¼ 2.13, 95% CI 1.29–3.88) was positively associated with asthenozoospermia. Whereas higher intakes of omega-3 polyunsaturated (OR ¼ 0.68, 95% CI 0.58–0.94) and of docosahexaenoic (OR ¼ 0.53, 95% CI 0.29–0.89) fatty acids were significantly associated with reduced odds of asthenozoospermia. Conclusion(s): Our findings suggest that the high intake of saturated and trans-fats was positively related to the odds of having asthenozoospermia. Conversely, inverse and dose-dependent associations were found between asthenozoospermia and intake of omega-3 polyunsaturated fatty acids. The observed associations of different types of fatty Use your smartphone acids underline the importance of the type of fat in the etiology of asthenozoospermia. (Fertil to scan this QR code SterilÒ 2015;103:190–8. Ó2015 by American Society for Reproductive Medicine.) and connect to the Key Words: Dietary fatty acids, asthenozoospermia, sperm motility, male infertility Discuss: You can discuss this article with its authors and with other ASRM members at http:// fertstertforum.com/eslamiang-dietary-fatty-acid-intakes-asthenozoospermia/
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nfertility is a global public health issue that affects men and women with almost equal frequency (1). Low sperm counts, poor sperm quality, genetic defects, hormonal imbalance, and anatomical problems might
contribute to male factor infertility (2). Some infertile men are asthenozoospermic because of poor sperm motility, which is an important predictor of male fertility (3). Asthenozoospermia is involved in more than 40% of infertile
Received August 10, 2014; revised September 22, 2014; accepted October 7, 2014; published online November 5, 2014. G.E. has nothing to disclose. N.A. has nothing to disclose. B.R. has nothing to disclose. M.-R.S. has nothing to disclose. A.-R.B. has nothing to disclose. A.H. has nothing to disclose. Supported by the National Nutrition and Food Technology Research Institute, Faculty of Nutrition and Food Technology, Shahid Beheshti University of Medical Science, Tehran, Iran (grant 401). Reprint requests: Azita Hekmatdoost, M.D., Ph.D., Department of Clinical Nutrition and Dietetics, Faculty of Nutrition and Food Technology, National Nutrition and Food Technology Research Institute, Shahid Beheshti University of Medical Sciences, No 7, West Arghavan Street, Farahzadi Boulevard, 1981619573, P.O. Box 19395-4741, Tehran, Iran (E-mail:
[email protected]). Fertility and Sterility® Vol. 103, No. 1, January 2015 0015-0282/$36.00 Copyright ©2015 American Society for Reproductive Medicine, Published by Elsevier Inc. http://dx.doi.org/10.1016/j.fertnstert.2014.10.010 190
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men (4). Vigorous sperm motility including the transition from progressive to hyperactivated motility is required for transport to the egg and penetration of the zona pellucida (ZP) (5). In the past decades, dramatic changes in the semen quality have been reported (6). A decline in sperm concentration and total sperm count was reported among healthy men. Jørgensen et al. (7) reported that only one in four men had optimal semen quality. Although the cause of such a dramatic change remains unidentified (8), lifestyle characteristics, such as dietary habits, have been implicated (9, 10). VOL. 103 NO. 1 / JANUARY 2015
Fertility and Sterility® In this regard, high consumption of saturated fatty acids (SFAs) and trans-fatty acids (TFAs) and low intakes of polyunsaturated fatty acids (PUFAs) and monounsaturated fatty acids are components of an unhealthy diet (11). Saturated fatty acids and TFAs, mostly found in animal fat products and hydrogenated vegetable oils, respectively, increase the risk of obesity, coronary heart disease, diabetes, and cancers (11, 12). Omega-3 PUFAs, such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), found in fish, walnut, and flaxseed, may reduce the risk of chronic disease (11). Surveys such as that conducted by Nissen and Kreysel (13) have illustrated a link between sperm motility and PUFAs. Conquer et al. (14) suggested that the level of DHA is lower in total ejaculate, sperm, and seminal plasma of asthenozoospermic men in comparison with normozoospermic men. Intake of flaxseed oil (15) and walnuts (16) containing alpha-linolenic acid is correlated with increased sperm motility. Omega-3 essential fatty acids play a vital role in sperm function, as they are important components of sperm cell membranes and may influence the ability of sperm to fertilize an egg and may also stimulate hormone production. Chavarro et al. (17) showed that higher TFA levels in sperm is associated with lower sperm concentration. Recent evidence suggests that the intake of TFAs is inversely related to total sperm count in healthy young men. There was also an inverse association between cholesterol intake and ejaculate volume (18). In addition, high intake of saturated fats was negatively related to sperm concentration (19, 20), whereas higher intake of omega-3 fatty acids was positively related to sperm morphology (19). Therefore, it seems that dietary fatty acid intake may be important in sperm quality and the etiology of male factor infertility. At present, there is a lack of published data on the relationship between dietary fatty acids and asthenozoospermia. The objective of the present study was to determine the association between asthenozoospermia and all fatty acids (i.e., six subgroups [SFAs, monounsaturated fatty acids, PUFAs, omega-6 PUFAs, omega-3 PUFAs, and TFAs] and nine individual fatty acid compounds [palmitic and stearic acids, oleic acid, linoleic acid, gamma-linolenic acid, arachidonic acids, alpha-linolenic acid, EPA, and DHA]).
MATERIALS AND METHODS Study Design and Subjects A hospital-based case-control study was conducted between January 2012 and November 2013 in the infertility clinics in Tehran, Iran. Eligible participants were men, aged 20 through 40 years. Cases consisted of 115 newly diagnosed asthenozoospermic men within past 3 months with normal sperm count and morphology. Sperm motility is graded as progressive motility, nonprogressive motility, and immotile according to the fifth edition of World Health Organization laboratory manual for the examination and processing of human semen (21). Asthenozoospermia was determined as ‘‘total motility’’ (progressive þ nonprogressive) of less than 40%, including both rapid and slow progressive motility, sluggish motility, and nonprogressive motility. It was additionally defined as progressive motility of less than 32%, which includes rapid, slow progressive and sluggish motility in the VOL. 103 NO. 1 / JANUARY 2015
same class, as reported within 60 minutes of ejaculation during the past 3 months. The total number (or concentration) of spermatozoa and percentage of morphologically normal spermatozoa was equal to or above the lower reference limits. Controls were 250 normozoospermic men from infertile couples, admitted to the same infertility clinics. Controls were frequency-matched with cases by age (4-year groups). The eligibility criteria for spermatogram variables were as follow: R15 106 of sperms/mL, R40% total motility, R32% progressive motility, and R4% normal forms, according to the strict criteria. Patients with a history of varicocele, cryptorchidism, or endocrine hypogonadism (defined by abnormal hormone levels). Individuals with karotype anomalies (including Y chromosome microdeletions) and a history of radiation and/or chemotherapy were excluded. Only those participants without a concurrent history of any nutrition-related conditions, such as diabetes, cardiovascular diseases, cancers, osteoporosis, or renal disease, were recruited. Participants with a history of the use of fatty acid supplements within the previous 3 months were also not included. The research protocol was approved by the Institutional Review Board and the Human Ethics Committee at the National Nutrition and Food Technology Research Institute of Shahid Beheshti University of Medical Sciences, Tehran, Iran. All research participants signed written, informed consents.
Semen Analysis All participants were instructed to abstain from intercourse for 3 days before providing the study specimen on-site by masturbation into a sterile wide-mouth and metal-free plastic container, with abstinence period verified by self-report on day of sample collection. Semen samples were collected in a private clinical examination room located adjacent to the infertility clinics, allowing the specimen to be liquefied for 30 minutes before analysis. Two semen samples were provided from cases and controls with an average 1-month interval; the average of the two samples was used for statistical analysis. Routine semen analysis was performed by an experienced technician according to standard procedures in the fifth edition of World Health Organization laboratory manual for the examination and processing of human semen (21). Test quality control validation was measured according to Cooper et al. (22). The external quality control was maintained by participation in the National Quality-Control Program conducted by the Iranian government. All laboratory analyses were performed by personnel blinded to the clinical diagnosis.
Dietary Assessment Information on usual diet was gathered by a validated 168item semiquantitative food frequency questionnaire (FFQ), which was modified to include Iranian food items eaten by Iranian adults (23). The consumption frequency of food items was obtained on a daily (e.g., bread), weekly (e.g., rice), monthly (e.g., fish), yearly basis (e.g., organ meats), or a never/seldom frequency and data from the questionnaire were transformed into the average monthly intake based on 191
ORIGINAL ARTICLE: ENVIRONMENT AND EPIDEMIOLOGY the assumption that each month is 30.5 days. The portion sizes for each food item in the FFQ were specified according the US Department of Agriculture portion sizes (e.g., apple, 1 medium; bread, 1 slice; dairy, 1 cup) whenever possible. When using the US Department of Agriculture portion size was not possible, household measures (e.g., beans, 1 tablespoon; chicken meat, 1 leg or wing; rice, 1 large, medium, or small plate) were used alternatively and portion sizes were converted to grams according to Iranian household measures (24). The nutrient content of raw foods and beverages were analyzed using the US Department of Agriculture and Iranian food composition tables. The Iranian food composition table is incomplete. However, for some items such as Kashk, vetch, wild plum, mint, sweet canned cherry, and sour cherry, which are absent from the US Department of Agriculture food composition table, the Iranian counterpart was used instead. Alcohol and opium consumption were not compromised in the analysis, because data about them were not collected owing to cultural barricades. The dietary fatty acids calculated were intake of total fatty acids, SFAs, monounsaturated fatty acids, PUFAs, omega-6 PUFAs, omega-3 PUFAs, and TFAs. Data were also obtained for the fatty acids palmitic and stearic (SFAs), oleic (omega-9 PUFA), linoleic, gamma-linolenic, and arachidonic (omega-6 PUFAs), alphalinolenic, EPA, and DHA (omega-3 PUFAs). Dietary habits were evaluated 1 year before the asthenozoospermia diagnosis for the cases and 1 year before the interview for controls.
Other Measurements Demographic information, including age, medical, occupational, family histories, lifetime history of tobacco use, intake of multivitamin and mineral supplements, lifestyle, and environmental exposures, was collected by private face-to-face interviews. Body weight was measured to the nearest 0.5 kg using digital scales (Soehne) with participants minimally clothed and barefoot. Height was measured while participants were in a standing position without shoes, using a nonstretch tapemeter fixed to a wall and was recorded to the nearest 0.5 cm. Body mass index (BMI) was calculated as kilogram per meter squared. Men reported their usual physical activity, which was recorded as specific activity, intensity, and duration. Total physical activity level was calculated and recorded in units of metabolic equivalent of task (MET) hours per day (MET.h/d) according to the a valid self-reported physical activity questionnaire (25).
Statistical Analysis The Kolmogorov Smirnov statistic was used to test normality of all continuous variables. The c2 test or Fisher's exact test was used to compare ordinal data between groups, whereas the Mann-Whitney or Student's t tests was used to compare continuous variables. The Mann-Whitney test was used to test the differences in crude fatty acid intake. Unconditional logistic regression models were used to estimate the strength of association between asthenozoospermia and fatty acid 192
tertiles (based on the distribution of controls). Intake of fatty acids was adjusted for the total energy intake by using the residual method (26). The core statistical model (model I) was corrected for age (4-year categories), BMI (kg/m2), smoking status (never/former/current), and heavy traffic near home (yes, no). The associations were tested in two additional models (models II and III). In model II, in addition to the confounding factors in model I, total energy intake was included as a covariate, as suggested by Willett and Stampfer (26) to reduce the random error. In model III, the associations were further adjusted for the total fatty acid intakes (energy adjusted). All the reported P values are two-sided with P< .05 was considered significant. All statistical analyses were performed using the Statistical Package for Social Sciences (version 17.0; SPSS).
RESULTS Four participants from the control group and three from the cases were excluded from the analysis as their log scales of total energy intake was either >3 or 70 blank items on the FFQ). Therefore, participation rates were 93% among asthenozoospermic cases and 94% among normozoospermic controls. After the initial screening, data regarding dietary habits were analyzed for 107 cases and 235 controls. The distribution of sociodemographic variables and selected risk factors among cases (n ¼ 107) and controls (n ¼ 235) is shown in Table 1. No significant differences between the cases and the controls were found in terms of age, marriage duration, abstinence time, endocrine parameters, ejaculate volume, total sperm/ejaculate, sperm concentration, normal forms of sperms, education, monthly family income, vitamin-mineral use, cell phone in pocket, hobbies or handicrafts with toxic products, fitted trousers, fitted underwear, self-car repair, and sitting with a laptop computer on legs, but there was a significant difference in BMI (P< .001), total motility of sperm (P< .001), progressive motility (P¼ .002), cigarette smoking (P< .001), and heavy traffic near home (P< .001). Cases reported a significantly higher total daily energy intake (2,650 kcal vs. 2,213 kcal; P< .001) compared with controls. Table 2 shows the main dietary sources and description of fatty acid subclasses for cases and controls. A number of different foods contributed to the intake of these fatty acid subclasses and specific fatty acids, and results from the Mann-Whitney test showed that consumption of total fatty acids, SFAs, omega-3 PUFAs, and TFAs, and of the individual fatty acids palmitic, stearic, EPA, and DHA significantly differed between cases and controls. Table 3 presents the results of the three multiple unconditional logistic regression models regarding the relation between tertiles of fatty acid intakes and asthenozoospermia as odds ratio (OR), 95% confidence interval (CI), and P values for the trend of asthenozoospermia regarding the intake of total fatty acids, each of the seven subgroups, and each of the individual compounds. According to the first model, intake VOL. 103 NO. 1 / JANUARY 2015
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TABLE 1 General characteristics of study participants (cases and controls). Characteristic Age (y), mean (SD) Marriage duration (y), mean (SD) BMI (kg/m2), mean (SD) Abstinence time (h), mean (SD) Semen parameters, mean (SD) Ejaculate volume (mL) Total sperm/ejaculate (106) Sperm concentration (106/mL) Total motility (%) Progressive motility (%) Normal forms (%) Cigarette smoker, n (%) Never smoker Ex-smoker (pack-year
