Physical Composition
Because the semen passes through the ejaculatory ducts and mixes with fluids from the seminal vesicles, the prostrate, and the bulbourethral glands, semen is composed of many different fluids.

The seminal vesicles produce a viscous, fructose-rich fluid. This fluid makes up approximately 65-70% of the semen base.

The whitish secretion from the prostate contains enzymes, citric acid, lipids, and acid phosphatase. This secretion composes around 25-30% of the semen base.

The testes eject approximately 200-500 million spermatozoa during ejaculation. They compose about 2-5% of the semen composition.

The bulbourethral glands produce a clear secretion that increases the mobility of the sperm cells in the vagina and cervix. It lessens the viscosity of the channel that the sperm cells swim through and also adds a cohesive, jelly-like texture to the semen. The glands contribute approximately less than 1% to the overall semen composition.

The volume of semen per ejaculation varies. A comparison of thirty studies suggests that the average amount of semen ejaculated was around 3.4 milliliters, although some studies found amounts as high as 4.99 milliliters or as low as 2.3 milliliters. It is believed that a prolonged gap between ejaculations increases the number of sperm in the semen but not an increase of the overall amount of semen.

Health Effects

Studies have revealed mixed conclusions about the impact of semen on the human body.

Some of the alleged positive impacts suggest that vaginal absorption of semen acts as an antidepressant and reduces the risk of breast cancer, while oral sex may help make a woman’s risk of pregnancy safer and more successful because she is swallowing her partner’s antigens. However, other studies suggest that vaginal absorption of semen could accelerate the development of an already existing cervical cancer, due to the prostaglandin elements in seminal plasma.

However, it is worth noting that semen can also be the vehicle for many sexually transmitted diseases, such as HIV/AIDS, herpes, or chlamydia. Although the proteins present in semen are potent against bacteria, fungi, and some viruses, these proteins are not active against Neisseria gonorrhoeae, which is the common cause of sexually transmitted diseases.

Oral sex is promoted by Planned Parenthood to be less risky than anal or vaginal sex – but HIV still can enter through open cuts and sores, or possibly by infecting the lining of the mouth. There are some documented cases of people getting HIV through their mouth.

Remember, while the chance of catching HIV from oral sex is considered to be low, you can easily catch other STDs, in particular gonorrhea and chlamydia.

Possible disadvantages of consumption of semen Semen can contain several viruses that may be transmitted via bodily fluids from an infected man. The most common example of such sexually transmitted infections (STI) are HIV (Human Immunodeficiency virus) and Hepatitis B and C viruses, herpes, Chlamydia etc.

There are some studies that suggest that vaginal absorption of semen can accelerate the development of an already existing cervical cancer. This occurs due to the prostaglandin present in semen.