I think I'm missing something. On the Results in study [b], they say
> Semen parameters did not seem affected by caffeine intake, at least caffeine from coffee, tea and cocoa drinks, in most studies. Conversely, other contributions suggested a negative effect of cola-containing beverages and caffeine-containing soft drinks on semen volume, count and concentration.
If tea and coffee don't cause an effect, but cola and soft drinks do, doesn't that imply it's sugar, not caffeine?
There is an ongoing discussion on the effect of caffein on sperm quality. There are articles which describes a possible route for DNA damage to the sperm from caffein https://www.cureus.com/articles/109365-effect-of-stress-and-.... From personal (lab) experience there is a clear difference to the smell of sperm from a coffee to a non coffee drinker, so it ends up there somehow. Whether it truly has an effect is still being discussed.
He didn't specify difference between de-caf coffee vs regular - only coffee vs non-coffee - so might be something other than caffeine that effects smell?
Coffee contains a large number of aromatic components that could be transferred to the semen. Just the way methyl mercaptan from asparagus can be transferred to your urine.
Could be correlated to issue 1 with plastic containers. In the US, soda generally comes in aluminum cans or 2L plastic bottles, whereas coffee and tea aren't.
Anyways, I still think sedentary lifestyles and stress play a larger role than plastics, but those are harder to isolate and control for researchers.
Well, the two sentences following your quote read:
> 2. As regards sperm DNA defects, caffeine intake seemed associated with aneuploidy and DNA breaks, but not with other markers of DNA damage
> 3. Finally, male coffee drinking was associated to prolonged time to pregnancy in some, but not all, studies.
And then goes on to conclude:
> The literature suggests that caffeine intake, possibly through sperm DNA damage, may negatively affect male reproductive function.
The whole abstract points at weak/inconclusive results, but we're definitely talking about caffeine here, not sugar.
> Semen parameters did not seem affected by caffeine intake, at least caffeine from coffee, tea and cocoa drinks, in most studies. Conversely, other contributions suggested a negative effect of cola-containing beverages and caffeine-containing soft drinks on semen volume, count and concentration.
If tea and coffee don't cause an effect, but cola and soft drinks do, doesn't that imply it's sugar, not caffeine?