Nutritional value in a serving of semen

Hi Alice,

Today a girlfriend and I were discussing the nutritional value of sperm. While performing oral sex, if you swallow, I was told that it is very high in protein. However, I was also informed that it is very high in calories. This may seem like a weird question, but I would like to know what nutritional benefits are involved when "swallowing" and how many approximate calories are in a man's ejaculation? Thank you for your help in this matter.


Dear P, 

There are no weird questions, only fascinating answers! For reference, the usual volume of ejaculate is between 1.5 to 5 milliliters (mL) per ejaculation, it’s approximately 5 to 25 calories, and contains anywhere between 20 million to 150 million sperm per milliliter. The volume of semen per ejaculation is determined by several factors including prior sexual activity, lifestyle, genetics, and age. Unless you're gulping gallons of semen each day, the amount of protein in an average “serving” of semen is no substitute for the sustenance and nutrition you get from real food. 

A typical sample of semen contains secretions from different glands found in the reproductive organs. Sperm only makes up a small portion of the semen sample. The other components include: 

  • Fructose and glucose. Studies on this topic show a large difference in concentration of fructose and glucose in semen. While exact amounts are harder to determine, it seems there are higher levels of fructose than glucose. 
  • Proteins. According to research studies, an accurate measurement of protein concentration can be difficult to obtain, however one study showed the average total protein concentration was about 5040 mg per 100 mL. 
  • Substances that support the survival of sperm. Seminal fluid also contains mucus, prostaglandins, clotting factors, ascorbic acid and alkaline fluid. 

Semen also contains enzymes, citric acid, trace elements of calcium, sodium, potassium, magnesium, zinc, and chloride. These elements are crucial for the process through which sperm mature, as well as for normal sperm functioning such as its movement and capacitation—a process which happens in the uterus that allows sperm to fertilize an egg. A lack of these elements can reduce sperm quality, while having too much of these elements can be toxic to sperm. Both a deficiency and excess of these elements can cause infertility for those individuals producing the sperm. 

While it may be nutrition information you're after, P, it's also important to note that semen can transmit sexually transmitted infections (STIs). Whether you choose to swallow or not, you may consider having a conversation with your partner ahead of time about sexual history and getting tested. It’s also worth noting that some people may experience an allergic reaction after ingesting semen. This reaction can be caused by the semen itself, which is known as seminal plasma hypersensitivity. However, an allergic reaction could also occur if a particular food or drug allergen is contained in the semen the person ingested, such as nut proteins or medications like penicillin. 

While seminal fluid contains essential substances for the health of sperm, it may not be as nutritious for the human body as a whole. If you choose to swallow, consider other ways to keep your body healthy, such as implementing safer sex practices.  

Last updated Jun 16, 2023
Originally published Oct 29, 1999

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