There is no inward release of literal, physical semen, except into the bladder.
Anything else results in blue balls.

I have been told that this is overproduction as a result of "aggrivating" foods. These are the same which would best replenish that which is lost. Can any actual cases by cited, in which semen production decreased in a person still eating a varied diet?

Thoughts should be given to the intent of intercourse. Is the partner being nourished or consumed? How 'bout you?

I've heard of Li Ch'ing Yuen ( http://www.itmonline.org/arts/hoshouwu.htm )
personally from a master of respectable lineage. Though this legend in longevity has been associated with tantra, few care to answer why he outlived every one of his wives!