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Friday, October 17, 2014 - 16:31
Poor performance

Moderate alcohol intake of at least five units every week is linked to poorer sperm quality in otherwise healthy young men, suggests research published in the online journal BMJ Open.

And the higher the weekly tally of units, the worse the sperm quality seems to be, the findings indicate, prompting the researchers to suggest that young men should be advised to steer clear of habitual drinking.
They base their findings on 1221 Danish men between the ages of 18 and 28, all of whom underwent a medical examination to assess their fitness for military service, which is compulsory in Denmark, between 2008 and 2012. As part of their assessment, the military recruits were asked how much alcohol they drank in the week before their medical exam (recent drinking); whether this was typical (habitual); and how often they binge drank, defined as more than five units in one sitting, and had been drunk in the preceding month.
They were also invited to provide a semen sample to check on the quality of their sperm, and a blood sample to check on their levels of reproductive hormones.
The average number of units drunk in the preceding week was 11. Almost two thirds (64%) had binge drunk, while around six out of 10 (59%) said they had been drunk more than twice, during the preceding month.
The analysis showed that after taking account of various influential factors, there was no strong link between sperm quality and either recent alcohol consumption or binge drinking in the preceding month. But drinking alcohol in the preceding week was linked to changes in reproductive hormone levels, with the effects increasingly more noticeable the higher the tally of units.
Testosterone levels rose, while sex hormone binding globulin (SHBG) fell; similar associations were also evident for the number of times an individual had been drunk or had binge drunk in the preceding month.
Almost half (45%, 553) of the men said that the quantity of alcohol they drank in the preceding week was typical of their weekly consumption. And in this group the higher the tally of weekly units, the lower was the sperm quality, in terms of total sperm count and the proportion of sperm that were of normal size and shape, after taking account of influential factors.
The effects were evident from 5+ units a week upwards, but most apparent among those who drank 25 or more units every week. And total sperm counts were 33% lower, and the proportion of normal-looking sperm 51% lower, among those knocking back 40 units a week compared with those drinking 1-5.
Habitual drinking was associated with changes in reproductive hormone levels, although not as strongly as recent drinking, while abstinence was also linked to poorer sperm quality.
This is an observational study, so no definitive conclusions can be drawn about cause and effect. And the researchers point out that the findings could be the result of reverse causation—whereby men with poor quality sperm have an unhealthier lifestyle and behaviours to start with.
But animal studies suggest that alcohol may have a direct impact on sperm quality, they say.
“This is, to our knowledge, the first study among healthy young men with detailed information on alcohol intake, and given the fact that young men in the western world [drink a lot], this is of public health concern, and could be a contributing factor to the low sperm count reported among [them],” they suggest.
And they conclude: “It remains to be seen whether semen quality is restored if alcohol intake is reduced, but young men should be advised that high habitual alcohol intake may affect not only their general health, but also their reproductive health.”

Sexually transmitted infections

Meanwhile in another study, high alcohol intake linked to heightened HPV infection risk in men. The findings were independent of other risk factors, such as number of sexual partners and smoking.

A high alcohol intake is linked to a heightened risk of human papillomavirus (HPV) infection among men, suggests research in the journal Sexually Transmitted Infections. The findings seem to be independent of other risk factors for the infection, such as number of sexual partners and smoking.
There is some evidence to suggest that alcohol impairs the workings of the immune system, both in terms of the initial protective inflammatory response to infection and the development of subsequent immunity.
And habitual drinking is known to increase susceptibility to bacterial pneumonia, septicaemia, tuberculosis and viral hepatitis. The researchers therefore wanted to find out if there was any association between drinking patterns and susceptibility to HPV infection.
They included 1313 men who were already taking part in the US arm of the HPV in Men (HIM) study, an international study that is tracking the natural history of HPV infection in men.
Participants filled in extensive and validated questionnaires on their long term sexual history and diet in the preceding 12 months. The food frequency questionnaire also asked about alcohol, including serving size, frequency, and type.
The men underwent a medical examination two weeks before the start of the study, and then every six months afterwards. Samples were taken from three genital areas to test for the presence of HPV.
Alcohol intake was grouped according to daily consumption of less than 0.10 g/day in the bottom 25% (quartile) of consumption up to 9.91 g or more a day for those in the top 25%. Note that in the UK, 7.9 g of alcohol is regarded as one unit, but this rises to 10 or more g of alcohol in other parts of the world.
Men who habitually drank more tended to be younger, smokers, of white ethnicity, to have had more sexual partners, and they were more likely to be circumcised—which may protect against infection—than those who drank less.
Average daily alcohol intake among those who tested positive for HPV was significantly higher than among the 514 men who tested negative. It was 4.52 g for those testing positive, compared with 3.13 g for those testing negative.
For those testing positive for the HPV types associated with increased cancer risk, average daily alcohol intake was 5.23 g; while for those testing positive for types not associated with cancer, it was 5.29 g; and for the four types against which the HPV vaccine is active, it was 6.31 g.
When further analysis was done of HPV prevalence, this was significantly higher among men in the top 25% of alcohol consumption compared with the bottom 25%: 68.9% versus 56.7% for any HPV type and 35.2% versus 22.8% for those types associated with increased cancer risk.
The data were also further analysed across categories of two potentially important risk factors: whether the men were smokers; and the number of sexual partners they said they had had.
The results showed significant associations between the highest levels of alcohol intake and HPV prevalence among those who had never smoked, for any type of HPV and for those types associated with an increased risk of cancer.
There was an association between the highest levels of alcohol intake, HPV prevalence and lifetime sexual partners, but it was not significant, and furthermore, it applied to any number of sexual partners.
This is an observational study, so no definitive conclusions can be drawn about cause and effect, and further research will be needed to confirm the findings. But the researchers point out that because neither smoking nor sexual activity seemed to influence HPV prevalence, some other factor is likely to have been involved, and that could be alcohol.
“Although these results cannot be considered causal and should be interpreted with caution, our findings do provide additional support to current public health messaging regarding the importance of moderate alcohol consumption, smoking cessation, and safe sex practices,” they write.
 

Copyright © Insurance Times and Investments® Vol:27.10 1st October, 2014
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