How men operate as sperm factories

By Professor Charles Kingsland, Consultant Gynaecologist & Specialist in Reproductive Medicine


The major difference between men and women is that men are sperm factories. We have all the ingredients to make sperm every single day of the week. Sometimes we are good at it, some days not so good. Increasingly, we are becoming worse at making sperm – more on that later.

As such, being the factories that we are, men can make sperm every day of the week, right up until the day we die. It takes about six weeks to assemble a sperm. Men then store them in tiny stables called seminiferous tubules deep within the testicle. At some opportune time we ejaculate a few million out.

During arousal, as we prepare for our sexual encounter, the sperm exit their homes and pass down a series of pipes. Just before they burst out into the daylight, they are squirted with semen, which has been waiting for them in the seminal vesicle, next to the sign marked exit. Semen contains lots of nutrients for the sperm, which helps them on their journey into the vagina and onto the egg.

Because men have the ability to reproduce up until the day we die, we males are typical mammals. There are very few animals that become sterile at any time before death.

Men tend to lose their fertility by just losing interest in putting sperm where it needs to go. Sport, mates, beer, work, not necessarily in that order, you understand, have a tendency to reduce our libido and our ability to perform. Men, therefore, lose their libido. Did you know that up to 50% of males, by the time they have reached their 50th birthday, have some degree of impotence; only 10 years to go for me then!

Women’s libido, interestingly, works on a completely different circuit. As such, women do not necessarily lose their libido in the same way as men, if at all.

Our sperm counts are also decreasing a little; it just so happens, that in the 1930s, a series of studies were performed on the sperm counts of Liverpudlian males. By coincidence, the counting of the sperm was carried out in almost the same way in which the World Health Organisation decided to quantify sperm, some 40 years later. We have, therefore, a reasonably accurate knowledge of the way sperm look now and what they looked like two generations ago. And it doesn’t look good ladies and gents.

Generally, sperm counts are up to 50% lower now than they were before the Second World War. We don’t actually know if the fecundity of sperm is lower, that is the ability of sperm to create a pregnancy, but the count is definitely reduced. Why do we think that is? Well there are a few useful guides to knowing the cause. Some are really obvious, others less so.

In an experiment, performed some years ago in the River Aire in Yorkshire, shoals of fish were kept in cages at the site of an out flow pipe near a factory depositing effluent into the river. A similar shoal of fish was kept in a cage five miles upstream and another five miles downstream from there outflow pipe. The fish and their offspring were then observed and examined a number of months later.

Some amazing findings were made: At the site of the out flow pipe, there was a remarkably high incidence of intersex, amongst the fish. That is with a lot of them you could not determine their sex, you couldn’t tell whether they were boy or girl fish. Downstream, the incidence of the fish’s sexual abnormalities were slightly less, but still apparent. Upstream, however, the majority of the fish were still happy with normal sexual characteristics.

So, why did this happen? You don’t need to be a brainbox to realise that something was getting into the water, some kind of pollutant that was affecting the reproduction and reproductive organs, in particular, of the fish.

This was sufficiently diluted the further downstream you went to affect the fish less. Upstream, the fish were hardly affected at all. (Water doesn’t flow upstream, just in case, you’ve lost the thread of this story).

Now then, what is the likely ingredient of the pollution in the water that has caused this sexual ambiguity? Probable culprit number one? Oestrogen, one of the world’s most powerful anabolic steroids – the most misunderstood and misinterpreted of all hormones on the planet yet one of the most abundant, which just happens to be my favourite, for a whole host of reasons, but not for the affect it would have on my gonads.

Oestrogen, is very difficult to break down and destroy completely. For example, when fertilisers get spread onto the land, they get broken down eventually, into their constituent parts, some of which have oestrogen like properties. They then flow from the land into tiny streams, which, in turn, flow into bigger rivers and then, onto the largest rivers, like the River Aire in Yorkshire. This oestrogen breakdown product must have got into the water and exerted its effect on the fish.

Coincidentally, did you know the average glass of water drunk by a person living in the South of England has been through another individual on at least 10 occasions? If oestrogen is one of the most difficult substances to break down, it’s not difficult to make the assumption, with some degree of correctness, that it’s getting into our bodies.

What if that same water gets into other animals and what if we eat those animals when they have been killed (obviously)? What would happen if we eat an animal, say a chicken that has been deliberately fed an anabolic steroid, say oestrogen, to fatten it up for Christmas? We males, after our yuletide feast may relax in the armchair next to the television watching the queens pre-recorded speech and trying not fall asleep, bellies full and brains empty, whilst the oestrogen we have inadvertently consumed sets about transforming us into females, so by the time we awake, in time for the national anthem, the trousers and checked shirt we were wearing pre-slumber have metamorphosized into a skirt and twin set. Perish the thought.

I could have sworn, on occasion, I’ve heard the shrinking of testicles upon entering a high street burger emporium, quietly and unnoticed, whilst my wife is shopping elsewhere, as men, of a similar disposition sink their teeth into a plumped up burger encased in a fluffy bap together with a generous portion of well lubricated French fries.

There are all sorts of other contaminants that can affect ones sperm count; testosterone, another feisty anabolic steroid can shrink your testicles just like the best of them. How can that be? I hear you protest, especially when you perceive these half man, half ape, gym bunnies preening themselves when not lifting impossibly large looking dumbbells that you could probably not disturb from their position on the rack against the wall.

Actually, testosterone has nothing to do with fertility in the sense that it has nothing to do with sperm count. In fact, testosterone has the effect of lowering numbers of sperm. What testosterone does do, however, is to provide you with the virility, muscularity and sheer manliness to give you the desire to deliver the sperm to its destiny.

If we return for a moment to the primeval swamp, men needed lots of testosterone to fight the hairy mammoth, bring food to the cave and at a later stage, fight off other humans. These testosterone fuelled individuals were necessary to protect the tribe. They were off fighting, whilst the less teratogenic, shall we say slighter or certainly less muscular individuals, helped the women folk to clean the cave, put up the shelves and, if the opportunity arose, fertilise the odd egg or two, all in the name of evolution of course.

Many years ago, long before, regulation took a necessary stranglehold on reproductive therapeutic processes, at a time when my old bosses were wanting to fill the donor banks of their fertility clinics, they would try to recruit would be suitable donors. Where would they look for potential donors? Reasonably intelligent people, not too strange in looks or behaviour, readily available with a steady and apparently plentiful supply of seminal fluid? Correct, they would go to the Medical School and try and recruit the students, the male of the species naturally.

Where in the lecture theatre would you find the individuals with the highest sperm counts? At the back of the theatre where the benches were usually populated by muscular and, when not hungover, reasonably fit thugs who went to form most of the front row of the Medical School first 15?

Or would their eyes wander down to the rows nearer to the lecturer, towards the front of the theatre in an attempt to engage the attention of the men, more in touch with their feminine side? More intelligent, less sporty, certainly more weedy, anorak neatly folded in their rucksack next to their small opaque box containing avocado and watercress sandwiches adjacent to a bright green, medium sized Granny Smith apple.

Correct, if you want to bet on your best provider of a bountiful sample, go for the males with the lower, but not insignificant testosterone levels and avoid the muscle bound would be Arnold Schwarzeneggers.

Got the picture? Testosterone is not good for your sperm. As a general rule, and it is only general ladies, big muscles, tiny balls. And, whilst we are on the subject, fertility has nothing to do with the size of your penis. As I remember my mother used to say, whilst bathing my brother and myself as children on a Sunday night, whether we needed cleansing or not, it’s not the size of the weapon, it’s the power of the shot that counts. Wars are usually started by men with big muscles and small balls, not the other way around.


So, how do you optimise testicular health and keep those sperm swimming towards the statue of Liberty and not doggy paddling their way over to Birkenhead?


Firstly, the reason why testicles wave freely in the breeze in a small sac, the scrotum, away from the warmth of the body, is that sperm like to be cool. Sperm are happiest being stored at a temperature of around 35 or so degrees Celsius, considerably lower that the balmy 37 degrees the rest of our torso enjoys.

It used to be said that if you wanted, or needed, a quick fix contraceptive, before a night out maybe, and gentlemen, this is by no means reliable, have a hot bath. So, keep your testicles cool for maximum potency. Avoid tight underwear and (unless you want to reduce your sperm count), don’t take hot baths.

Ironically, being too hot and fit can have a negative effect on your fertility. Keep healthily fit, but don’t go mad. I tend to say, if you run more than 15 miles per week, that’s too fit. Of course, we all have differing fertilities; some of us may have inherited better sperm counts than others. I’m just talking generalities here.

Would you choose a long distance cyclist in your Olympic sperm squad, with all those hours of your testicles being crushed up against a saddle, or would you choose hiker, walking the hills of the Lake District, with his baggy waterproofs, stopping regularly to admire the Lakeland views? Fairly obvious isn’t it?

If you have a virulent fever, or heaven forbid, something as potentially devastating as Man Flu, where your temperature soars and you have no option but to stay at home, in comfort, with your nurturing partner, supporting you unconditionally, you can bet your bottom dollar that the infection will reduce your reproductive powers for a few weeks, until the seminal factory returns to a full and a hopefully cooler shift.


Sperm like good food to nourish them – foodstuff that don’t move and grow above the ground, products that you don’t see immediately adjacent to the checkout till at the supermarket. The reason they are cynically placed there is because you don’t need them, they are generally of poor quality and they are cheap. Similarly they tend to be addictive and after you have eaten or read them, your mood has a tendency to decline, just like reading a cheap magazine or reading Facebook for half an hour or so.

Specifically, there are some foodstuffs that, in theory, are beneficial to sperm – those high in zinc and vitamin E especially. If you feed vitamin E to male rats, they become more virile and potent, reaching for the aftershave and donning the hair gel. Although scientists have never been able to demonstrate the same effects of these substances in humans, it’s worth a try and will certainly not be harmful.

On reflection, I have seen more than a few rodent like individuals roaming the streets of Liverpool on a Saturday night. I wonder if they have been stocking up on the vitamin E before leaving the nest for a night out.

Zinc is another sperm enhancing substance. Like vitamin E, it can improve sperm performance in the test tube, but whether that improves the baby making capacity of the creatures in the wild is open to debate. Nevertheless, and not unlike vitamin E, in regular doses, these ingredients are not harmful.

Naturally, we find these items, yes you’ve guessed it, in all things we males do not necessarily like to eat and I’m thinking vegetables here. Anything that grows by fresh water is particularly nourishing to sperm. A real powerhouse of goodness is the greatly undervalued vegetable, watercress. Zinc is also found in spinach, pumpkin seeds, nuts, beans and mushrooms.

Do you remember Popeye that muscle bound, spinach eating sailor? He was a character devised and promoted by the Post War American government in an attempt to get the population eating more spinach as it was believed at the time, that this unattractive small green leafed vegetable contained large quantities of cheap readily available iron.

In 1870, a German chemist, Erich Von Wolf, was researching the amount of iron in spinach and other green vegetables. When writing up his findings in a notebook, he misplaced a decimal point, making the iron content far more generous than in reality. There are actually only 3.5 milligrams in a 100 gram portion as opposed to 35 milligrams that the errant Doctor actually documented.

Similarly, when you boil spinach, the iron content is converted to a less readily absorbable type of iron. So, in summary, spinach is nowhere near as good for us as we first thought. You might as well suck on a paperclip.

Incidentally, the mistake made by Doctor Von Wolf was discovered and corrected in the 1930s but here’s the thing; humans are very reluctant to change old facts and traditions, even though they have long since proved to be wrong. So, we still think that spinach is a great source of iron. It’s not.

In the same way, generally speaking, snap frozen vegetables are far more nutritious than fresh vegetables. There is inevitably a time lag in getting fresh vegetables from the farmers field to the supermarket shelves during which time many vitamins and minerals may have been deactivated, whereas if the same vegetable has been frozen immediately at source, those goodies are preserved.

We all have enemies, but if the sperm are our reproductive superheroes, who are the baddies, the Jokers, Riddlers and Daleks of the scrotal world?


No surprises here. Enemy number one is Testosterone, the incredible bulk. Found in gyms mainly and in quantities, albeit, very small, in those testicle gnashing protein drinks.


Testosterone is closely followed by nicotine. I could write a book on the dangers of nicotine, oh, you’ve already heard that it’s not good for you? So why do you still smoke?

I cannot believe sometimes the number of men and women who come to my fertility clinic, loaded up to the gunnels with reassuringly expensive fertility enhancing products, living their lives around their next spinning class. Yet, when I ask them whether they smoke, they blush, look down to the floor and admit to smoking five cigarettes a day. I immediately double this gure, as it is a well-known fact amongst Doctors that nicotine affects the brain in such a way that smokers automatically half every number in their minds.

Nicotine has a devastating effect on sperm function. Not only that, it can affect your babies health as well and make them grow half a brain or three heads or even worse. I confess, I’m exaggerating about the three heads. It’s just that I cannot overemphasise the potential damage that nicotine can do to a sperm, all his brothers and sisters, the scrotum and the person that carries them around in his loose underpants.


Number three; alcohol. I can’t be a hypocrite here because I like alcohol. I can pontificate, as a non-smoker about the evils of tobacco, but I feel slightly embarrassed when it comes to alcohol. There is no doubt that excess alcohol is not good for sperm. It gets them drunk so they don’t swim well. An intended brisk front crawl to New York can readily turn into a fumbled doggy paddle to Runcorn under the in uence of a few shandies.

There is no need for gentlemen to become teetotal in order to reproduce because, as I have said elsewhere, a significant proportion of inadvertent conceptions take place under the influence of alcohol, but there is no doubt that a restriction on intake makes the little swimmers just a bit more athletic.

Professor Charles Kingsland