Sperm & Selenium
Selenium is a mineral that is essential for health, and is often found in dietary supplements aimed at male fertility. But why? What does it do? Do you really need a supplement?
What does it do?
Selenium that is ingested makes its way to the testicles where it plays several different roles in fertility in males. It is incorporated into a molecule called ‘GPx4’ during early sperm production (spermatogenesis). When sperm are not yet fully developed they produce a high volume of a molecule called GPx4. As they develop into mature sperm, they need GPx4 to form parts of their structure, specifically the protective wall around the mitochondria - which is where the sperm generates its energy to move. So could a lack of the GPx4 molecule could lead to an unstable sperm midpiece, meaning it cannot release enough energy to swim well? Potentially. There is not enough significant evidence to support this mechanism directly yet, but selenium supplementation in selenium deficient people has shown optimisation in production of GPx4, and a strong link has been identified between a lack of GPx4 and male infertility.
Another role that selenium plays in male fertility is as an antioxidant. Several studies have shown that certain molecules that have selenium embedded in them are essential in counteracting the effect of oxidative stress. Oxidative stress occurs when there are too many free radicals in the body, and in spermatogenesis the negative outcomes of this include poor sperm motility and fragmentation of the DNA they contain.
Furthermore selenium has long been associated with development of the brain, and plays an important role in brain function. Decades of research have linked low selenium levels to increased seizures, and the essential role of selenium in neurological function is undisputed. Following this research, some studies have noted that in males in particular, the brain (where selenium is needed for development) and the testes (where selenium is needed for spermatogenesis) actually compete for available selenium if the levels in the body are low. This has been investigated by measuring brain function and behaviour in castrated mice who are depleted of selenium, versus mice with testes who are depleted of selenium. These studies highlight the importance of adequate intake of selenium for all body functions.
Do you get enough?
The daily recommended value for selenium in males older than 19 years old is 75mcg. In a national nutrition assessment, about 1 in 4 men did not meet the lowest reference value for selenium intake - this means their intake was worryingly low. Selenium is found in plenty of ‘normal’ foods, and can be easy to add into your diet with food rather than supplements. Some great sources of selenium are:
Brazil nuts (76mcg per approx 5 nuts)
Green lentils (40mcg in 4 tablespoons)
Turkey (13.3mcg in 70g serving)
Seeded bread (10mcg in 2 slices)
Cashew nuts (8.7mcg in a handful)
Though supplements are undeniably helpful in some cases, often a balanced healthy diet with some adaptations could meet all of your nutritional needs, selenium included. It is always worth reading the label on supplements to check what they actually contain - for example, different brands of ‘male fertility’ supplements vary in their selenium content between 35-100mcg per tablet!
If you are concerned about your selenium intake, or have more questions about sperm health and nutrition, contact us via the website or social media.
References
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DOI: 10.1016/j.freeradbiomed.2022.07.022