The effects of dietary lycopene supplementation on human seminal plasma

Abstract

Objective: To investigate whether lycopene levels in blood and seminal plasma increase after dietary supplementation with a natural source of the compound, and whether any potential increase of lycopene levels in semen translates into increased free-radical trapping capacity in the seminal plasma.

Methods: Reactive oxygen species are detrimental to the health and function of spermatozoa. Semen contains enzymatic and non-enzymatic defence mechanisms to combat such species, and lycopene, a dietary antioxidant, forms part of the non-enzymatic arm. Immuno-infertile men have significantly lower levels of lycopene in their semen, and oral lycopene therapy can improve various seminal variables in idiopathic infertility. Whether this improvement is a direct consequence of increased lycopene levels in semen, resulting in an increased radical scavenging ability, remains unknown. Blood and seminal lycopene levels were measured in healthy volunteers, using high-performance liquid chromatography, before and after a period of dietary supplementation. The antioxidant capacity of seminal plasma was also assayed to determine if supplementation results in a measurable increase in seminal radical scavenging ability.

Results: There were statistically significant increases in blood and seminal plasma lycopene levels after dietary supplementation. The increase in seminal and blood lycopene levels showed a strong positive correlation (r = 0.84, P < 0.05). There was no measurable increase in the total radical scavenging capacity of semen.

Conclusion: This study confirms the presence of lycopene in human semen, the levels of which can be significantly increased after dietary supplementation with a natural source of lycopene. Further studies to establish whether this would also be the case in infertile men, with possible associated improvements in their seminal quality, are warranted.