Even if you are young and drink alcohol only during the weekends, that could be enough to harm your reproductive health as researchers have found that drinking just five units of alcohol a week could affect sperm quality of young men.
The researchers also found that 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.
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The effects were evident from five-plus units a week upwards, but most apparent among those who drank 25 or more units every week.
"This is, to our knowledge, the first study among healthy young men with detailed information on alcohol intake," the researchers said.
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"Young men should be advised that high habitual alcohol intake may affect not only their general health, but also their reproductive health," they added.
They study involved 1,221 Danish men between the ages of 18 and 28, all of who underwent a medical examination to assess their fitness for military service, which is compulsory in Denmark, between 2008 and 2012.
The analysis showed that 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.
The study appeared in the journal BMJ Open.