[Associations between dietary inflammatory index and male reproductive parameters]

Association of dietary total antioxidant capacity, alternative healthy eating index, and dietary inflammatory index with semen quality in men seeking infertility treatment

Background

Since the association between dietary quality scores and semen quality remains unclear, we carried out a hospital-based cross-sectional study to investigate the association of Dietary Total Antioxidant Capacity (dTAC), Dietary Inflammatory Index (DII), and Alternative Healthy Eating Index (AHEI) scores with semen quality in men seeking infertility treatment.

Methods

This study enrolled 210 men with unexplained or idiopathic infertility. Semen samples were collected and analyzed according to the WHO 2010 criteria. Dietary data was collected using a 168-item semi-quantitative food frequency questionnaire (FFQ) developed for Tehran Lipid and Glucose Study. Multivariable logistic regression models were used to estimate the relationship between dTAC, AHEI, and DII scores with abnormal semen in crude and adjusted models.

Results

There were no significant differences across quartile categories of the dTAC, AHEI, and DII scores regarding semen parameters. There was a trend toward a significant direct association between DII and abnormal semen risk (p = 0.01). Infertile men in the highest quartile of DII had a 2.84 times higher risk of abnormal semen in the crude model (OR: 3.84; 95% CI: 1.64-8.95); such that remained after adjusting for several potential confounders. There was no significant association between dTAC or AHEI and the risk of abnormal semen in infertile men, either before or after adjusting for potential confounders. Total energy (p = 0.05), fat (p = 0.02), saturated fat (p = 0.02), mono-saturated fat (p = 0.009), Thiamine (Vitamin B1) (p = 0.02), Niacin (Vitamin B3) (p = 0.03), Calcium (p = 0.01), and Selenium (p = 0.01) were inversely associated with semen normality.

Discussion

The study suggests that certain dietary factors may affect semen quality, and the mechanisms underlying the observed associations are likely multifactorial, involving complex interactions between diet, oxidative stress, inflammation, and hormone levels. Further research is required to confirm the results, fully elucidate the mechanisms underlying the associations, and identify specific dietary interventions that may improve male fertility outcomes.

Dietary Inflammatory Index and Risk of Asthenozoospermia: A Hospital-Based Case-Controlled Study in China

Background: Evidence of associations between a pro-inflammatory diet and asthenozoospermia risk is limited. We therefore performed a case-controlled study to investigate associations between pro-inflammatory diet using dietary inflammatory index (DII) scores and asthenozoospermia risk in China.

Methods: Our hospital-based case-controlled study comprised 549 incident asthenozoospermia men and 581 healthy controls. All were interviewed at the infertility clinic in Shengjing Hospital of China Medical University from June 2020 to December 2020. DII scores were calculated based on dietary intake which were assessed using a validated food frequency questionnaire. Semen parameters were analyzed according to World Health Organization guidelines. An unconditional logistic regression model was used to estimate odds ratios (ORs) and corresponding 95% confidence intervals (CIs) for asthenozoospermia risk. The lowest tertile served as the reference category for regression analyses.

Results: After adjustment for age in the primary multivariable model, we failed to determine a significant negative association between DII and asthenozoospermia risk (for the highest tertile of DII scores compared to the lowest tertile) (OR = 0.77, 95% CI: 0.57–1.03). Similarly, non-significant associations were also identified in the multivariable model after adjusting for more potential confounders (OR = 0.86; 95% CI: 0.58–1.27). Additionally, in subgroup analyses stratified by age, body mass index, and smoking status, non-significant results were consistent with the main findings.

Conclusions: To our knowledge, this is the first study exploring this particular topic. Our research does not support an association between DII scores and asthenozoospermia risk. Further prospective studies with more DII relevant foods and nutrients are warranted to confirm our findings.

The Association Between Dietary Inflammatory Index and Sex Hormones Among Postmenopausal Women in the US

AIMS

Diet has been found to have an important effect on sex hormones. The effect of diet-induced inflammation on sex hormones has not been studied in detail among women. Therefore, we aimed to investigate the association between energy-adjusted dietary inflammatory index (E-DII) and sex hormones among postmenopausal women.

METHODS

This study used data from the National Health and Nutrition Examination Survey (NHANES) 2013-2016 waves. A total of 1183 postmenopausal women who provided information on two 24-hour dietary intake recalls, sex hormones including total testosterone (TT), estradiol (E2), TT/E2, sex hormone-binding globulin (SHBG), free estradiol (FE2) and free testosterone (FT), as well as selected covariates were included. Linear regression and restricted cubic spline evaluated the association between E-DII and sex hormones. Effect modification by body mass index (BMI) and type of menopause was then examined in stratified analysis.

RESULTS

After adjusting for covariates, linear regression showed that E-DII was positively associated with TT (P=0.035), FT (P=0.026) and TT/E2 (P=0.065). TT (P-nonlinear = 0.037) and TT/E2 (P-nonlinear = 0.035) had significant nonlinear association with E-DII. E2 (P-nonlinear = 0.046) and FE2 (P-nonlinear = 0.027) depicted a nonlinear U-shaped significant association with E-DII, the two inflection points were found at the E-DII score of -0.22 and 0.07, respectively, the associations in natural menopausal women were more pronounced.

CONCLUSIONS

Our study indicates that several indicators of androgen and estrogen were associated with E-DII in postmenopausal women. Further research is needed to understand the underlying mechanisms.