Oxidative Stress: the main cause of sperm DNA damage

What is Oxidative Stress, how do we diagnose it, and what can be done to improve male fertility? Dr Amy Barrie, Laboratory Director at CARE Chester and CARE Liverpool, answers your questions about this little-known cause of male infertility.


For the 1 in 6 couples who need help starting a family, male factors will be the cause of up to 50% of infertility issues. Though a general semen analysis still remains the ‘gold standard’ for assessing the quality of sperm (checking factors like volume, number, motility, morphology and more), 25 – 40% of male infertility cases could remain ‘unexplained’ after a semen analysis.

One factor which could be causing this ‘unexplained’ infertility is Oxidative Stress. High levels of oxidative stress have been linked to poor sperm function and cell DNA damage, potentially increasing the risk of failed IVF outcomes. Previously, we haven’t been able to identify this Oxidative Stress in semen samples, but we have recently launched our new SOS (Sperm Oxidative Stress) test, greatly improving our range of diagnostic fertility assessments for men. But what is Oxidative Stress and how does it affect male fertility?


What is oxidative stress?

As a result of our cells (including sperm) using the oxygen we breath to produce energy, highly reactive molecules, known as free radicals or reactive oxygen species, are produced. These free radicals perform vital functions for our health, such as helping to fight infection, however in excess they can be very damaging. Antioxidants produced by the body counteract these free radicals, keeping the system in balance, but when the production of free radicals exceeds the body’s production of antioxidants, the excess free radicals can cause damage to tissues such as proteins, cell membranes and the DNA of cells, including sperm. This is called Oxidative Stress.


What causes oxidative stress?

Our ability to produce antioxidants is controlled by our genetic makeup and can be influenced by lifestyle, such as a diet rich in antioxidants, like fruit and vegetables. The production of free radicals is increased by many environmental factors including smoking, alcohol, and a poor-quality diet high in saturated fats, as well as aging and excess weight. Our body's internal production of antioxidants should be adequate to balance the production of free radicals, but for many individuals there may be an excess of free radicals, leading to cell damage and long-term health effects.

CARE Fertility sperm

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Oxidative stress and male fertility

High levels of oxidative stress have been linked to poor sperm function, abnormal semen analysis results, and failed IVF outcomes. There is evidence that high levels of oxidative stress can cause changes in the sperm cell membranes, affecting their morphology and motility, as well as causing damage to their DNA. This DNA damage could result in DNA errors within an embryo, in turn causing lower pregnancy rates and a higher risk of miscarriage.


CARE Fertility oxidative stress


Testing for oxidative stress

Though a classic semen analysis may show the effects of oxidative stress (such as reduced quality or motility of sperm), it would not be able to show the reason behind it. Our new SOS (Sperm Oxidative Stress) test quickly determines if a patient high levels of oxidative stress by assessing the balance of free radicals and antioxidants in a semen sample. This test can be done at the same time as a normal semen analysis, or at any other time during fertility treatment at CARE. A great advantage of this test is that there is no need for sperm to be frozen and transported to our specialist laboratory, as with Sperm DNA damage screening. Since Oxidative Stress can cause sperm DNA damage, our SOS test is a quick indicator of whether further, more complex testing is necessary.


Who should be tested for oxidative stress?

  • Partners of women with a history of two or more pregnancy losses
  • Males over the age of 40
  • Males with suboptimal semen analysis results (particularly low morphology or motility)
  • Males with poor lifestyle, body mass index over 30, who smoke, have high alcohol intake or poor diet.


Treating high levels of oxidative stress

If your SOS test shows high levels of oxidative stress, we may recommend lifestyle changes and antioxidant supplements, which include vitamin C and specific minerals to help reduce the free radicals which can damage sperm. We may also recommend further, more complex testing to assess the level of DNA fragmentation in a sperm sample, and may then recommend ICSI if the level of DNA fragmentation is high.

The important thing to remember is that once we have a diagnosis of Sperm Oxidative Stress (or any other male infertility issue), there are many things we can do to give you your best chance of conceiving.

How do I get an SOS test?

Our exciting SOS test is currently available at all CARE clinics. If you are interested in the SOS test, please contact the team at your local clinic. Or call our new patient enquiry team on 0800 564 2270.

With 1 in 20 men affected by sperm inefficiency, a correct diagnosis is crucial in ensuring successful fertility treatment. Our new SOS test gives even more information about sperm quality, and with treatment often simple, it’s well worth speaking with your CARE team about whether our SOS test can help you.

A short video showing Computer Assisted Sperm Analysis at CARE, which can be performed alongside the SOS test.

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