Antioxidants, Oxidative Stress and your Fertility – part One

Sperm have a pretty tough time. They begin life in the testes, where – after a gruelling 74 days on the production line – they wind their weary way through coiled tubes to reach the prostate gland. It’s from here that sperm will be ejaculated during sex. They’re catapulted at a monumental speed into a hostile environment which seeks to attack and thwart them at every opportunity. The vagina. If the determined travellers can navigate these harsh conditions, their chances of fertilising an egg are still pretty slim.

A sperm must battle it out against millions of his competitors on a marathon journey. Even though the distance between the sperm and the egg is only about 10cm, the tiny sperm’s whip-like tail can only propel it at about 3mm per hour, meaning the journey can take forever!

How well sperm perform is measured by ‘sperm quality’ – an indicator that can tell us if a man has any underlying fertility issues. Sperm quality is made up of four different aspects. The number of sperm produced, how well they can move, their physical characteristics and the quality of their DNA.

As if the little swimmers don’t have enough to worry about, there are many factors that can damage them – leading to a decline in a man’s overall sperm quality. Many of these factors come hand in hand with the modern and busy lives we lead – for example, a man’s job, diet and sleeping pattern can all influence his sperm quality. Sperm are sensitive little things and the slightest inconvenience can make their one big goal in life unattainable. In fact, in 50% of couples facing fertility issues, defective sperm can be pin-pointed at the root of their problems.

Another problem that influences sperm quality is the amount of reactive oxygen species (ROS) in a man’s testes.

What are ‘ROS’?

ROS – which are also known as free radicals – are very volatile molecules which contain oxygen. Normally, natural processes in the testes lead to the production of a small amount of ROS in seminal fluid (the fluid in which sperm are nurtured). These small amounts of ROS are needed for normal sperm function. But if the amount of ROS is left unchecked, they can become bad news – causing something known as ‘oxidative stress’ – which damages cells.

Under oxidative stress, the ROS can wreak havoc on sperm, damaging sperm DNA and the membrane surrounding sperm cells and reducing the ability of sperm to move spontaneously. This undermines sperm quality in a variety of ways and can have a devastating effect on a man’s fertility, because if sperm want to stand a chance at fertilising an egg, they need to be in mint condition!

Professor Allan Pacey, fertility and sperm specialist at the University of Sheffield said,

We think that sperm damaged by free radicals can be defective in many ways. But an important concern is that the genetic material inside the sperm head can become damaged and this can lead to infertility either by preventing how well sperm fertilise the egg, or by increasing the chances of a miscarriage.

It’s no wonder that oxidative stress in the testes is now being blamed as one of the fundamental causes of fertility problems in men.

Antioxidants and their importance in male fertility

Luckily, molecules known as antioxidants are at hand to help stop ROS causing any damage. Antioxidants can be found in the testes (as well as other places), and they balance out the effects of ROS by preventing any cells being exposed to oxidative stress. It’s important that the correct balance of ROS and antioxidants is maintained, as if the balance is off and there are too many ROS in the testes, sperm cells are put under oxidative stress and a man’s fertility is threatened.

And this imbalance is exactly what happens in some men who are facing fertility issues caused by a low sperm quality. But, fortunately, men can control the level of antioxidants in their testes in order to lower their chances of oxidative stress and damaged sperm. There are two ways a man can do this.

Antioxidants and diet

Photo credit: maira.gall / Foter / CC BY-ND

First of all a man can alter his diet. Observational studies have shown that men can get the beneficial effects of antioxidants by making sure they eat foods rich in antioxidants. In other words, men who have more antioxidants in their diet tend to have better quality sperm. Here’s a list of some the most antioxidant rich foods – which include many types of fruit and vegetables.

In one study, researchers looked at sperm DNA damage (which was used as an indicator of overall sperm quality) in relation to micronutrient intake in 80 fertile men. The researchers were looking for the presence of antioxidants such as vitamins C and E, b-carotene, zinc and folate in the men’s diets. They found that the men with the highest intake of vitamin C had roughly 16% less sperm DNA damage than men with the lowest intake. There was a similar effect linked to intake of vitamin E, folate and zinc. High intake of micronutrients was particularly beneficial for sperm quality in older men, which is important, as older men’s sperm are more likely to be of sub-optimal quality.

Antioxidant supplements

But, perhaps an easier and more effective way for a man to increase his antioxidant levels is by taking daily antioxidant supplements in the form of tablets. Many studies have shown that men who take such supplements have a higher sperm quality than men who don’t. And some studies show that men who take antioxidant supplements are more likely to conceive a child with their partner than those who don’t.

To try and paint a clearer picture on how best to take antioxidants to improve sperm quality, a recently published review looked at the results of 17 other studies (containing 1665 men) that examined the effect of antioxidant supplements on sperm quality and a man’s likelihood of conceiving with his partner.

In the different studies, men took a variety of different antioxidant tablets for an average time of 18 weeks. The review found that 82% of the studies found an improvement in either sperm quality or pregnancy rate after the men had taken antioxidants. Six out of the ten studies looking at pregnancy rates found an increase in pregnancy after men had been taking antioxidants and 12 out of 16 studies looking at sperm quality found an improvement in at least one aspect of sperm quality after men had been taking the supplements.

Exactly how long men should take antioxidants to get their beneficial effects is still a little bit of a grey area. But the review found that in two out of the three studies that found no improvements after antioxidants, the oral supplements were only taken for eight and nine weeks. The researchers believed that the men in these studies probably weren’t taking the antioxidants long enough to warrant any effect.

Professor Pacey explained:

What the data from studies does not tell us so far, is what dose and combination of antioxidants is the best one to use and also how long they should be taken for, to achieve the best results. However, given that we know that it takes at least 90 days to produce a sperm from start to finish, then any man that decides to take them should perhaps do so for at least 3 months before they decide to try for a family.

There is still much speculation about exactly which tablets (or combination of tablets) are best to take to most effectively improve sperm quality. In Part Two of this article we will go through some of the options available for men who want to try and boost the quality of their sperm with antioxidant supplements. Stay tuned!

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