Does boron supplementation lower Sex Hormone-Binding Globulin (SHBG) levels and affect sperm quality?

Boron's Effects on SHBG and Sperm Parameters

Boron supplementation can lower Sex Hormone-Binding Globulin (SHBG) levels and may improve certain sperm parameters, though evidence is limited and clinical guidelines do not specifically recommend it for male fertility enhancement.

Effects on SHBG and Hormone Levels

• Boron supplementation (10mg daily) has been shown to significantly decrease SHBG levels within 6 hours of consumption in healthy male volunteers 1
• After one week of daily 10mg boron supplementation, studies have demonstrated increased free testosterone levels and decreased plasma estradiol 1
• Dihydrotestosterone, cortisol, and vitamin D levels were also elevated following one week of boron supplementation 1
• The mechanism appears to be related to boron's influence on steroid hormone metabolism and binding proteins 1

Effects on Sperm Parameters

• Dietary boron supplementation has been shown to increase sperm concentration and total sperm production in animal studies 2
• Boron levels in blood plasma (r = 0.65) and seminal plasma (r = 0.54) showed positive correlation with sperm progressive motility in goat studies 2
• However, high concentrations of boron may have adverse effects on sperm parameters, suggesting a dose-dependent relationship 3
• Current medical guidelines do not identify boron as a recommended supplement for improving male fertility 4

Safety Considerations

• The American Urological Association (AUA) and American Society for Reproductive Medicine (ASRM) state that the benefits of supplements are generally of questionable clinical utility in treating male infertility 5
• Human studies in workers with high occupational boron exposure (with blood boron concentrations up to 570.6 ± 160.1 ng B/g) did not show adverse effects on semen parameters or reproductive hormone levels 6
• The NOAEL (No Observed Adverse Effect Level) for fertility effects of boric acid in male rats was evaluated to be 17.5 mg B/kg body weight per day 7
• Concentrations of boron that exert reproductive toxicity in experimental animals are not typically reached under conditions of normal human exposure, even in occupational settings 7

Clinical Implications

• Despite some promising findings in animal studies and limited human research, major fertility guidelines do not currently recommend boron supplementation for male infertility 5
• The WHO guidelines strongly recommend (based on low-quality evidence) that there are insufficient data to recommend supplemental therapies for the treatment of men with abnormal semen parameters 5
• For men concerned about fertility, focus should be placed on established factors affecting semen quality such as smoking, excessive alcohol consumption, certain medications, and environmental exposures 4
• Men with fertility concerns should consult with reproductive specialists for appropriate evaluation rather than relying on unproven dietary interventions 4

Research Limitations

• Most studies examining boron's effects on reproductive parameters have been conducted in animals, with limited high-quality human trials 2, 3
• The heterogeneity of supplement studies and lack of standardized protocols make it difficult to draw robust conclusions 5
• Current evidence does not support routine use of dietary supplements including boron for improving male fertility 4
• Further well-designed, placebo-controlled randomized trials with primary outcomes of time to pregnancy and live births are urgently needed 5