Semen is primarily water, but contains trace amounts of almost every nutrient the human body uses. It has somewhat higher amounts of commonly deficient minerals, such as potassium, magnesium
, and selenium. One typical ejaculation contains 150 mg of protein, 11 mg of carbohydrates, 6 mg fat, 3 mg cholesterol
, 7% US RDA potassium and 3% US RDA copper and zinc. When metabolized, protein yields 4 kcal/g, carbohydrate also yields 4 kcal/g, and fat yields 9 kcal/g. Hence the food energy in the typical ejaculation is 0.7 kcal (2.9 kJ).
There is no risk in ingesting the semen of a healthy man. Swallowing semen carries no additional risk other than those inherent in fellatio. Fellatio does carry some transmission risk for sexually transmitted diseases such as HIV or herpes, especially for people with bleeding gums
or open sores.
Even if semen is cold before the individual ingests it, viruses can stay active for a long period of time once outside the body.
Research has suggested that performing unprotected oral sex
on a person infected with human papillomavirus
(HPV) might increase the risk of oral or throat cancer
. The study found that 36 percent of the cancer patients had HPV compared to only 1 percent of the healthy control group. It is believed that this is due to the transmission of HPV because this virus has been implicated in the majority of cervical cancers.