Table 1 Studies investigating the relationship between vitamin D status and semen parameters in healthy and infertile men
From: Vitamin D and assisted reproduction technologies: current concepts
Author, year, [reference #] | Country | Study design | Cases included | Sample size | Groups of patients identified by serum 25(OH)D levels | Statistical analysis used | Main finding(s) | Main confounding factors considered |
|---|---|---|---|---|---|---|---|---|
Ramlau-Hansen et al., 2011 [29] | USA | Cross-sectional | Healthy men aged 18-21 | 307 | 3-24 ng/ml: low (33.5%) 25–37 ng/ml: medium (33.5%) 38–91: high (33%) | Spearman’s rank correlation test; Multivariable linear regression | No significant association between 25(OH)D levels and sperm parameters | Season |
BMI | ||||||||
History of diseases | ||||||||
Duration of abstinence | ||||||||
Time from ejaculation to analysis | ||||||||
Blomberg Jensen et al., 2011 [27] | USA | Cross-sectional | Healthy men aged 18-21 | 300 | <10 ng/ml: deficient (12%) 10-20 ng/ml: insufficient (32.7%) 21-30 ng/ml : sufficient (41.7%) >30 ng/ml: high (13.7%) | Kruskal Wallis test; Multivariable linear regression | Positive association between 25(OH)D levels and sperm progressive motility and morphology | FSH |
Duration of abstinence | ||||||||
Time from ejaculation to analysis | ||||||||
Serum calcium levels | ||||||||
Season | ||||||||
Hammoud et al., 2012 [30] | USA | Cross-sectional | Healthy men aged 18-67 | 147 | <20 ng/ml: deficient (12.4%) 20-49 ng/ml: intermediate (75.2%) ≥50 ng/ml: high (12.4%) | Multivariable linear regression | Negative association of both deficient and high 25(OH)D levels with sperm parameters | Season |
Age | ||||||||
BMI | ||||||||
Alcohol intake | ||||||||
Smoking | ||||||||
Yang et al., 2012 [31] | China | Cross-sectional | Healthy and infertile men aged 20-40 | 195 (healthy group); 364 (infertile group) | <10 ng/ml: severely deficient 10-20 ng/ml: deficient 21-30 ng/ml: insufficient >30 ng/ml : sufficient | Spearman’s rank correlation test; Multivariable linear regression | Positive association between 25(OH)D levels, sperm motility and morphology also in the infertile group | Testosterone |
Season | ||||||||
Duration of abstinence | ||||||||
Time from ejaculation to analysis |