Semen actually looks like a pretty good, cheap, natural multi-vitamin supplement
http://www.jackinworld.com/library/science/semcomp.html
• ascorbic acid (vitamin C, for tissue maintenance)
• blood-group antigens (from immune system)
• calcium (mineral)
• chlorine (oxidizing agent)
• cholesterol (steroid alcohol present in body fluids)
• choline (base, part of the vitamin B complex)
• citric acid (occurs during cellular metabolism)
• creatine (nitrogenous substance found in muscle)
• deoxyribonucleic acid (DNA)
• fructose (sugar used for energy)
• glutathione (peptide amino acid)
• hyaluronidase (enzyme)
• inositol (sugar found in muscles)
• lactic acid (byproduct of muscle use)
• magnesium (mineral)
• nitrogen (gas found in all living tissue)
• phosporus (mineral)
• potassium (mineral)
• purine (compound of uric acid)
• pyrimidine (organic base)
• pyruvic acid (formed from either glucose or glycogen)
• sodium (salt)
• sorbitol (body alcohol)
• spermidine (catalytic enzyme)
• spermine (ammonia compound found in sperm)
• urea (from urine)
• uric acid (from urine)
• vitamin B12 (for proper function of nervous system and metabolism)
• zinc (mineral)
I imagine you'd have to drink a plethora of cum though; due to the minute quantities
