I'm trying to find studies or statistical proof that supplements actually do increase semen volume. Not sperm count (sperm is < 5% of semen volume). Not reports that certain supplements help testosterone production. I'm looking specifically for evidence of semen volume increase. For example, here is a study that reports an increase in semen volume from Ashwagandha: Clinical Evaluation of the Spermatogenic Activity of the Root Extract of Ashwagandha (Withania somnifera) in Oligospermic Males: A Pilot Study. It was a study of men with oligospermia but at least showed that a full-spectrum root extract of Ashwagandha (675 mg/d in three doses for 90 days) resulted in 53% in semen volume among those men.

I have seen a couple of studies in (non-human) animals about lecithin increasing semen volume, such as this one: Enhancement of sperm quality and fertility-related parameters in Hubbard grandparent rooster fed diets supplemented with soybean lecithin and vitamin E.

Does anyone else know of any studies or other reliable evidence linking specific supplements and dosages to an increase in semen volume?