Research shows that smokers' sperm counts are on average 13-17 per cent lower than non-smokers, writes Michael Kelly
MOST MEN would be aware of the impact which smoking has on health and wellbeing. Statistics on the health implications of smoking make for grim reading (and an entirely compelling case for quitting): smokers lose an average of 10-15 years from their life expectancy and half of all smokers will die from a smoking-related disease.
It substantially increases the risk of cancer (including lung, mouth, throat, stomach, pancreas, kidney, bladder and colon), heart disease, strokes, low birth weight and many other diseases.
Smoking is thought to cause 30 per cent of all cancers and 90 per cent of lung cancers. It is the single most important preventable cause of illness and death, and in this country is directly responsible for the deaths of 7,000 people each year.
But the impact of smoking extends well beyond even these horrific consequences. A less known fact about the dangers of the habit is the impact that it has on men’s fertility and sexual health.
There is significant focus on the impact that smoking during pregnancy has on the health of an unborn baby, but doctors also believe that refraining from smoking will increase the chances of conceiving a baby in the first place.
Interestingly, they also believe that smoking, even occasionally or periodically, can affect fertility potential and outcomes.
“It is well established that smoking can have a negative impact on men’s sexual health,” says Dr Angie Brown, chairwoman of Ash Ireland. “Smoking can affect the entire wellbeing of a person in terms of lung capacity, cardiovascular and general vascular disease. Inevitably, directly and indirectly, that will adversely affect sexual and reproductive health.”
Numerous reports and studies have confirmed that smoking reduces the quality and quantity of sperm. A report by Pressinger Sinclair for example indicated that smokers’ sperm counts are on average 13-17 per cent lower than non-smokers.
Key indicators of sperm quality, according to the World Health Organisation, (ejaculate volume; concentration of spermatozoa; sperm motility) are drastically reduced in men who smoke and there is also an increase in dead and malformed sperm.
Loni Burman at the University of Buffalo Medical School established that smoking has two effects on sperm – firstly, it reduces overall sperm quality by a measurable amount and, secondly, it also stops the adhesion of the sperm to the egg, a vital part in the conception process.
A 2003 American Society for Reproductive Medicine report found that men who smoke cigarettes have lower sperm count and motility and increased abnormalities in sperm shape and function.
They concluded that smoking in men should be regarded as a significant fertility risk factor. The society also pointed out that when a man in a relationship smokes, passive smoke has a harmful effect on the fertility of the female partner.
The report concluded that smoking cessation improves natural fertility as well as the success rates of infertility treatments such as in vitro fertilisation (nearly twice as many IVF attempts are required to conceive in smokers than in non-smokers).
Developments in genetics have allowed scientists to uncover something even more shocking about the impact of smoking on reproductive health – the oxidants in cigarette smoke can cause permanent genetic damage to sperm and this damage can be passed on to offspring.
Cigarette smoke is toxic to the genetic make up of all cells but it has a particularly negative effect on sperm since sperm have no way of repairing any damage to their genetic material. Scientists believe that this may explain higher miscarriage rates among couples where the male partner smokes.
The terrifying consequence of this could be that paternal smokers are passing on a permanent legacy of genetic ill-health to their children. A report in the Journal of the National Cancer Institute found that children at age five whose fathers had smoked an average of a pack a day or more for five years prior to conception faced a 70 per cent higher risk of developing cancer than did the offspring of non-smoking men.
Importantly, the report accredited this problem not to passive smoke impacting the mother of the child, but smoke-generated free radical damage to DNA in the father’s sperm.
The June 2007 issue of the Journal of the American Association for Cancer Research reported on a Canadian study which also found that children could inherit genetic damage from a father who smokes.
“Here we are looking at mutations in the DNA of sperm,” said Carole Yauk, lead author of the study and research scientist at Health Canada. “If inherited, these mutations persist as irreversible changes in the genetic composition of off-spring. We have known that mothers who smoke can harm their foetuses, and here we show evidence that fathers can potentially damage offspring long before they may even meet their future mate.”
A study of 51 healthy males aged 18-51 (22 smokers and 29 non-smokers) investigated the potential association between smoking, antioxidant levels in seminal fluid, and damage to sperm DNA.
It found that oxidative damage in sperm DNA was 50 per cent higher in smokers compared with non-smokers, while the concentration of alphatoco-pherol (a form of vitamin E) in seminal plasma was 32 per cent lower in smokers.
As if all of this weren’t bad enough, other reports have found that men who smoke have lower sex drives and less frequent sex than non-smokers (who said smoking was sexy?).
In addition because the mechanism of developing an erection is dependent on healthy veins, smoking can also lead to impotence by causing damage to blood vessels. Smoking results in a build-up of fatty deposits in the arteries which in turn blocks the inflow route for blood in to the penis.
In addition, nicotine stimulation in the brain is thought to cause rapid contractions in penile tissue, again restricting arterial blood flow. Action on Smoking and Health (Ash) in the UK believes that smoking increases the risk of erectile dysfunction by about 50 per cent for men in their 30s and 40s, while a study carried out by the British Medical Association (BMA) estimated that about 120,000 men in the UK suffer from impotency because of smoking.
Furthermore, nearly 90 per cent of smokers (male and female) were unaware of these risks.
The good news, however, is that like most smoking-related health issues, erectile problems caused by nicotine stimulation can be immediately reversed if the person stops smoking.
“It is now clear that smokers are more likely to develop impotence in just the same way that they develop heart disease,” says Prof Ian Eardley, consultant urologist at St James Hospital, Leeds. “If they can stop smoking, there is every chance that they will prolong normal sexual function.”