In the cross-sectional study, 400 infertile men according to approved andrologist's indices participated to our study from July 2019 to December 2019, from Yazd Reproduction Research Institute. Inclusion criteria include age between 20 to 55 years, sperm count less than 15 million per milliliter, normal morphology less than 4%, semen volume less than 1.5 ml and progressive motility less than 40%. Also, exclusion criteria include chronic diseases, testicular atrophy, ejaculatory disorder, hypospadiasis, stenosis, varicocele, adherence to specific diets, non-response to more than 35 items of food frequency questionnaire and underreporting and over-reporting of energy intake (less than 800 and more than 4,200)(11, 12). General and dietary information was collected by a trained nutritionist. All subjects completed the consent at the baseline of the study .
Physical Examination And Lifestyle Variable
Physical activity data were collected using a validated and reliable questionnaire (International Physical Activity Questionnaire)(13). The IPAQ provides information about levels of inactivity, moderate activity, strenuous activity and walking. In addition, we gathered the data regrding frequency (days per week) and duration (minutes per day) for all type of activities.
Socioeconomic status (SES) of the study participants was determined according to variables, such as home situation variables situation (landlord-tenant), washing machine and dishwasher (yes-no), number of overseas trips, has car (yes-no), individual occupation, education (number of years of study).
Anthropometric data were measured by standard methods. The body mass index (BMI) and Waist to Hip Ratio (WHR) calculated according to standard protocol of World Health Organzation (WHO), based on minimal clothing and no shoes, using Falcon scales (Seca, Hamburg, Germany) to the nearest 0.1 kg. Also, all measurements were recorded with an accuracy of 0.1 cm. Hip Circumference (HC) was measuredو since the hips are the widest part of buttocks and Waist Circumference (WC) was measured midpoint between the last rib and the iliac crest (umbilical level). BMI and WHR were calculated based on this formula: weight (kg)/height (m2) and WC (cm)/HC (cm), respectively (14).
Dietary intake was assessed by using a semiquantitative Food Frequency Questionnaire (FFQ). The validity of this questionnaire is confirmed in Iran(15). The FFQ including 168 food items which was designed according to frequency of consumption of the common foods of one’s country during the past 12 months (number of times consumed daily, weekly, monthly, and annually). FFQ was filled out by a trained dietitian, by interviewing. The validity of meat assessments, using this questionnaire has been confirmed according to the food pattern records over the past year. The total meat intake was defined as red meat, poultry, fish, tuna, processed meats and organ meats. Household measurements were monitored by a nutritionist to calculate the total energy and nutrients consumed in actual food consumption (grams per day). Information on alcohol use was not collected for cultural reasons and was therefore not analyzed. The dietary habits of each person were assessed one year prior to infertility diagnosis.
Semen samples should be collected after 3 days of abstinence. Before transferring the samples into the container, the temperature of the container should be close to the body temperature of 37 ° C. Semen samples were kept in sterile containers at 37 ° C for 30 minutes. They were then evaluated and analyzed according to the WHO Fifth Edition Laboratory Guidelines(16). Four parameters related to semen and sperm including semen volume, sperm concentration, normal sperm morphology and sperm motility were measured.
In the present study, the anthropometric, demographic and semen quality indicators of participants were categorized and summarized using KruskalWallis test. Fisher's exact test was also used to classify them into meat consumption quarters. Mixed linear models were used to investigate the relationship between meat consumption and semen quality indicators.
In these regression models, semen quality indicators such as semen volume, sperm count, sperm motility types and normal sperm morphology were compared with meat intake quartiles. quartile 1 was considered as the lowest and quartile 4 was considered as the highest consumption. Variance calculations were evaluated as 95% CI. Participants' information, including age, BMI, WHR, physical activity, pesticide use, and smoking, which had been shown to be a risk factor for decreased semen quality, were monitored as a confounding variables. All models were adjusted for age, BMI, WHR, use of toxins, energy intake, physical activity and smoking. P-value < 0.05 was considered as the level of significance. Statistical analysis was determined using SPSS software (version 22, Chicago, IL, USA).