Mediterranean diet linked to improved sperm quality

A recent study in the journal Nutrients evaluates whether adherence to the Mediterranean diet (MD) affects sperm parameters.

Study: Observational Cross-Sectional Study on Mediterranean Diet and Sperm Parameters. Image Credit: losinstantes / Shutterstock.com

Background

In Western countries, 15-25% of couples experience infertility problems. Previous research has shown that about 50% of infertility cases can be attributed to male factors.

In addition to congenital problems, other factors that impact male fertility include diabetes, hypertension, insulin resistance, overweight/obesity, and atherosclerosis. Cigarette smoking, excessive alcohol consumption, and lack of physical activity also negatively affect male fertility.

Recent studies have also provided new insights into how an unhealthy diet influences male fertility. For example, preserved and processed meat, alcohol, sugary beverages, and foods with high levels of saturated fatty acids negatively impact sperm quality.

Male reproductive health is significantly benefitted from a low intake of trans fats and saturated fats and a high consumption of omega-3 fatty acids, carotenoids, polyphenols, vitamins, and antioxidants. Fish, whole grains, poultry, fruits and vegetables, seafood, and low-fat dairy products improve sperm quality.

Typically, a Western diet involves a high intake of ultra-processed foods that contain a significant amount of sugars and fats. The regular intake of these foods creates nutritional imbalance and introduces excessive calories.

A high-calorie diet causes obesity, which has been linked to insulin resistance, particularly hyperinsulinemia and hyperglycemia. Obesity induces changes in glucose metabolism in the sperm. Impaired glycolysis enhances oxidative stress, which affects sperm quality and male reproductive function.

Many studies have highlighted the positive effects of MD against non-communicable diseases, including cardiovascular diseases (CVDs). MD involves the high consumption of seasonal vegetables and fruits, fish, nuts, cereals, legumes, a moderate amount of wine, and a low intake of meat and dairy products.

MD is rich in antioxidants and anti-inflammatory molecules, monounsaturated fatty acids, fibers, and low in saturated fat. Both anti-inflammatory and antioxidant molecules function as a gene modulator and reactive oxygen species (ROS) scavenger. Previous studies have shown that natural dietary components improve sperm parameters, including sperm motility, viability, and concentration.

About the study

The current study hypothesized that higher MD adherence would positively benefit male reproductive health and sperm parameters. The present observational cross-sectional study evaluated the association between MD adherence and sperm parameters.

Individuals who were referred to the Andrology and Reproductive Medicine Unit, University Hospital of Padova, between September 2022 and July 2023 for semen analysis were considered for this study. All participants were between 18 and 45 years of age and did not have a history of varicocele, testicular cancer, endocrinopathies, genetic causes of infertility, and semen infections. Semen samples were collected from participants after two to seven days of sexual abstinence and were analyzed.

The body mass index (BMI) of all participants selected in this study was estimated. Adherence to MD was assessed using a validated 14-point a priori Mediterranean Diet Adherence Screener (MEDAS) in the presence of a dietitian. 

Study findings

A total of 300 non-obese males were enrolled in this study, and their mean age was 34.6 years. About 32%, 36.7%, and 31% of the cohort reported low, medium, and high adherence to MD, respectively. Notably, smokers and non-smokers showed different MD adherence.

The extent of MD adherence significantly correlated with sperm parameters. Being obese or overweight negatively influenced the hypothalamic-pituitary-gonadal axis and affected spermatogenesis and energy metabolism. Adherence to MD prevented metabolically unfavorable phenotypes in men.

Due to the low levels of saturated fatty acids and trans fatty acids, as well as adequate levels of polyunsaturated fatty acids fraction (PUFA) and monounsaturated fatty acids, MD is positively correlated with male fertility status. All major predictors of fertility potential, including sperm motility, morphology, viability, and count, were significantly and positively correlated with the MEDAS score. This finding strongly highlights that nutrition regimen could be a possible biomarker of sperm abnormalities, particularly in those who remain idiopathic.

Participants who belonged to the lowest tertile of MD adherence score exhibited poor sperm motility, count, and concentration as compared to those with a high MD adherence score. In line with the findings of a previous study, the current study revealed that MD is positively associated with sperm parameters, particularly sperm count and concentration.

Conclusions

A key strength of this study is its sample size. The exclusion of known andrological conditions and the homogeneous evaluation of the MD regimen by a single dietitian are other strengths of this study.

The current study also has some limitations, including its cross-sectional and observational design, which made it challenging to identify the causal factor linking MD adherence to semen parameters.

Despite these limitations, the study findings indicate that higher adherence to MD promotes better semen quality in males, whereas reduced MD adherence alters semen parameters, particularly sperm count. Therefore, nutritional intervention could be an effective and non-invasive strategy for men with poor sperm quality.