Association Between Meat Intake and Semen Parameters Among Iranian Infertile Men: A Cross-sectional Study

Objective: Previous studies have proven the effect of dietary patterns on semen quality indicators, but research on the relationship between meat intake and semen quality is limited. Therefore, this study was conducted to investigate the relationship between Meat intake with semen quality. Methods: In this cross sectional study, 400 infertile men were recruited into study during their fertility investigation in Yazd Reproductive Sciences Institute Diagnosed by an andrologist according to the inclusion criteria. Multivariate logistic regression was used to determine the relationship between meat intake and semen parameters. All data were analyzed using SPSS V. 22 software. Results: We found that intake of canned tuna can have two different effects on sperm motility in infertile male. Intake of canned tuna according to the serving size stated in quartile 2, leads to a decrease in the percentage of immotile sperm from 52.93 (CI95%, 51.15-54.71) to 46.55 (CI95%, 44.56-48.54) (Ptrend=0.036). On the other hand, there is an increase in the percentage of immotile sperm from 46.55 (CI95%, 44.56-48.54) to 52.88 (CI95%, 50.94-54.82) in the highest quartile of canned tuna intake.Also, no signicant relationship was observed between intake other types of meats and sperm quality indices. Conclusions: We found that intake of canned tuna,base on serving size of quartile 2, is associated with lower percentage of immotile sperm, on the other hand high intake of canned tuna increase percentage of immotile sperm in Iranian infertile men. More extensive studies are recommended in this regard. study without a history of chronic diseases and the use of any medication or dietary supplement. 34.5% were smoker and 25% were previous smokers. In this study, we concluded that decreased semen quality was signicantly associated with increased BMI, WHR, and age. This study has several strengths, including high sample size in new diagnosed patients (in past 1 year), with minimum error in dietary recall history, using FFQ with high validity for estimating food intake and eating habits, repeating semen analysis for men with infertility in laboratory. However, the present study has some limitations. FFQ depends on the memory of the participants being interviewed also it does not allow precise estimation of portion size of foods consumed. Moreover the effect of stress on men was not evaluated in this study. We found that Consumption of tuna has two different effects on sperm motility. intake of canned tuna, based on serving size of quartile 2, is associated with lower percentage of immotile sperm due to canned tuna is a rich source of unsaturated fatty acids. But on the other hand high intake of canned tuna increase percentage of immotile sperm in Iranian infertile men. The proposed mechanism in this regard is related to the high concentration of metal pollutants in canned tuna. further investigations are needed to conrm these results and to recognize the underlying mechanisms.


Introduction
Infertility affects 7% of the total men population (1). More than 25% of infertility due to decrease semen quality causes are related to male fertility disorders (2).
According to a meta-analysis, involving 185 studies and 42,000 men, semen quality has decreased over the last 40 years (3). However, according to previous studies men infertility might be due to anatomical disorders such as varicocele, obstruction of the ducts, or ejaculatory disorders (4,5). But about 40-90% of the causes of male infertility are due to a decrease in semen quality and abnormal sperm health indicators (4,5). Several reasons have been suggested for semen quality decline, but smoking, alcohol consumption, pesticides in food, unhealthy eating habits, inadequate intake of many essential micronutrients and vitamins are the main causes of this reduction(6). According to previous studies, diet can affect spermatogenesis, which is measured by evaluating the quality of semen. For example, red meat intake reduces the concentration and number of sperm. Fish consumption, on the other hand, is associated with higher sperm morphology (7)(8)(9). Increased intake of processed meats is also associated with oligoasthenoteratospermia and asthenospermia (10).Therefore, for further evaluation, we examine the relationship between meat consumption and sperm quality indicators in infertile men.

Study Population
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 speci c 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 .
using this questionnaire has been con rmed according to the food pattern records over the past year. The total meat intake was de ned as red meat, poultry, sh, 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 Analysis
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.
Statistical Methods: 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 signi cance. Statistical analysis was determined using SPSS software (version 22, Chicago, IL, USA). Results: Based on the Table 1, infertile men with an average age of 33.66 years, were in the age range of 20 to 55 years, who entered the study without a history of chronic diseases and the use of any medication or dietary supplement. 34.5% were smoker and 25% were previous smokers. In this study, we concluded that decreased semen quality was signi cantly associated with increased BMI, WHR, and age.  blood levels of lead and cadmium had lower serum levels of the hormones including and testosterone in comparison with healthy healthy men. they also have found that sperm count, motility, and semen volume were signi cantly lower in infertile men(28). So many other studies suggested the relationship between higher serum levels of lead and cadmium and attenuated sperm quality (29)(30)(31)(32).
This study has several strengths, including high sample size in new diagnosed patients (in past 1 year), with minimum error in dietary recall history, using FFQ with high validity for estimating food intake and eating habits, repeating semen analysis for men with infertility in laboratory. However, the present study has some limitations. FFQ depends on the memory of the participants being interviewed also it does not allow precise estimation of portion size of foods consumed. Moreover the effect of stress on men was not evaluated in this study.

Conclusion
We found that Consumption of tuna has two different effects on sperm motility. intake of canned tuna, based on serving size of quartile 2, is associated with lower percentage of immotile sperm due to canned tuna is a rich source of unsaturated fatty acids. But on the other hand high intake of canned tuna increase percentage of immotile sperm in Iranian infertile men. The proposed mechanism in this regard is related to the high concentration of metal pollutants in canned tuna. further investigations are needed to con rm these results and to recognize the underlying mechanisms.

Declaration
Ethical Approval and Consent to participate Availability of data and materials The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.

competing interests
The authors declare that they have no competing interests" in this section.

Funding
This study was supported by a grant from the Isfahan University of Medical Sciences, Islamic Republic of Iran.
Authors'contributions FH, RGh: designed research; FH: conducted research; FH,LDM: provided essential materials;SPSH: analyzed data; FH: wrote paper; FH: had primary responsibility for nal content. The authors read and approved the nal manuscript.