What is oxidative stress and how does it affect male fertility?

Usually, a seminogram is performed in the male fertility study. This test analyzes certain semen and sperm parameters (such as sperm concentration, motility and morphology) to evaluate the semen quality of the male.

However, parameters such as oxidative stress or sperm DNA integrity, which are important aspects related to male infertility, are not analyzed by performing a semen analysis.

Currently, this topic is gaining great interest, as it has been shown that seminal ROS levels are increased in 30-80% of men with fertility problems.

What is oxidative stress?

Oxidative stress is a situation that occurs when there is an imbalance between reactive oxygen species (ROS) and the antioxidant system.

ROS (a type of free radicals) are oxidizing agents produced in normal cellular metabolism. These molecules are highly reactive and give rise to chain reactions that can lead to cell damage. This is where the antioxidant system comes in.

The antioxidant system is responsible for protecting against the damaging effects of free radicals, either by reducing their formation, preventing oxidation or repairing the damage produced.

What leads to an increase in ROS?

Several factors can lead to increased levels of ROS. These factors include:

• Tobacco and alcohol.
• Obesity.
• Diabetes
• Environmental contaminants and pesticides.
• Electromagnetic radiation.
• Stress.
• High temperatures.
• Infections
• Varicocele.
• Presence of immature spermatozoa or leukocytes in the ejaculate.

Factors leading to increased ROS

When the antioxidant system is not able to neutralize the excess of ROS, the balance is lost and oxidative stress appears.

How oxidative stress affects spermatozoa

First, it is important to mention that certain physiological levels of ROS are essential in functions such as sperm hyperactivation and capacitation and the acrosomal reaction, processes necessary for the sperm to fertilize the oocyte.

However, spermatozoa are particularly vulnerable cells to the effect of ROS, mainly for two reasons:

• Spermatozoa are highly specialized cells that have reduced their cytoplasm during their formation process, so their antioxidant content is limited.
• The sperm membrane is rich in polyunsaturated fatty acids. These fatty acids can undergo lipid peroxidation by ROS, which causes the sperm membrane to lose its fluidity.

The loss of fluidity in the membrane affects the motility of the spermatozoa, as well as their ability to unite (fuse) with the oocyte and fertilization to occur. In addition, oxidative stress can lead to sperm DNA damage and fragmentation and apoptosis (cell death).

The integrity of sperm DNA is essential in the reproductive process. After fertilization of the egg, the DNA of the sperm will be half of the genetic content of the embryo. Therefore, if the sperm DNA is fragmented, it can cause problems in achieving gestation or in its correct evolution.

Damage of oxidative stress to spermatozoa

Although the study of sperm DNA fragmentation is quite widespread in fertility centers, tests to evaluate oxidative stress in semen are not common and tend to be used more for research purposes.

You can read more about sperm DNA fragmentation in the following article: Sperm DNA fragmentation and its implication on fertility.

What is the treatment?

To protect spermatozoa from damage caused by excess ROS and oxidative stress, antioxidant therapy has been proposed. These can be ingested through the diet or through supplements. Among the most commonly used are vitamins C and E, selenium, zinc, coenzyme Q10 and L-carnitine.

In any case, before taking any dietary supplement, it is necessary to consult a specialist. An excess of antioxidants could lead to reductive stress and a decrease in the physiological levels of ROS, which are necessary for the spermatozoon to develop its functions correctly.

Similarly, if the male does not present oxidative stress, antioxidant therapy would not be indicated, as it could also lead to reductive stress.

Recommendations for reducing oxidative stress in spermatozoa

On the other hand, moderate exercise contributes to a better oxidative balance in the semen and to an increase in testosterone levels, thus improving semen quality. In addition, the male may make other lifestyle changes, such as quitting smoking (if applicable).

FAQs from users

How do antioxidants help male fertility?

Oxidative stress is an imbalance in the cellular environment, produced by toxic factors that surround us and that are especially aggressive to sperm. It can affect sperm in several ways: their development throughout their evolution, their morphology, their ability to move (motility), and their fertile capacity since it damages their DNA. This explains the sperm damage.

Antioxidants are substances, essentially natural products, that we find in our food and try to rebalance the balance of sperm metabolism between free radicals (oxidative stress) and antioxidants in the body (the body's ability to combat them), increasing the latter and repairing the damage caused.

Multiple studies have shown that antioxidants (L-Carnitine, Coenzyme Q10, Vitamin E, Vitamin C, Selenium, Zinc) produce an increase in both the number of spermatozoa and their mobility.

In spite of all this, the effectiveness of antioxidants is only given by correct diagnosis and an adequate therapeutic guideline when faced with a certain process of infertility.

Are berries beneficial for male fertility?

Yes, this type of fruit, red berries, are very rich in antioxidants, which could help counteract the effects of oxidative stress and thus help improve seminal quality.

Do chemicals cause oxidative stress in sperm?

Yes, certain chemical agents, pollutants, pesticides, herbicides... can lead to an increase in reactive oxygen species (ROS) and to a loss of balance with the antioxidant system, leading to oxidative stress.

Can there be oxidative stress in spermatozoa if the seminogram is normal?

Antonio Forgiarini from Next Fertility Valencia tells us whether oxidative stress may be present even though the results of the semen analysis are normal:

Well it's not usual. Normally if we ask or if we have oxidative stress, it will reflect in the seminal parameter, so we have a few spermatozoa or they're not moving correctly, but sometimes it could happen. We can suspect that we have some problem of oxidative stress so some damage in the DNA chain of the spermatozoa when we have bad results with a normal semen and good or sides so a low fertilization so the embryo will not develop correctly to blastocyst or we have some problem like miscarriages when we don't know any other cause so sometimes it's the case to investigate about this reason.

Recommended reading

If you want to know more about seminal quality, we recommend you to read this article: Sperm quality: how it is measured and what to do to improve it.

On the other hand, if you wish to obtain more information about varicocele, you can visit the following link: What is testicular varicocele - Causes, symptoms and treatments?