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The 16 Fabulous Foreskin Functions - a critical analysis

April 11, 2017

This was a preliminary version of the article. Click HERE for the current version or visit

The 16 Foreskin Functions - what are they? Anti-circumcision activists claim that the foreskin provides 16 essential functions. They say that circumcision eliminates these irreplaceable functions, rendering a man physically harmed and sexually crippled. Intactivists claim that anyone unaware of these functions must be ignorant of the incredible value of the foreskin! Woe to doctors and nurses who are unaware of these valuable foreskin benefits!

One of our first actions on the Circumcision Choice Facebook page was to publish a weekly series on the 16 Functions of the Foreskin. We devoted a post to analyzing each function. Where possible, we used explanations provided by leading intactivists to understand a function and its value. We've compiled the entire series here for easy reference. The entries are updated and include links to studies, articles, and other sources.


The argument goes as follows: During the normal, flaccid state the glans of an uncircumcised man is covered by the foreskin. As sexual arousal begins the foreskin will retract to expose his glans. When a partner sees the glans, she knows that the man is aroused. By contrast the glans of a circumcised man is always exposed, regardless of whether or not he is sexually aroused. Therefore a partner cannot determine just by seeing the glans whether the man is aroused.

This “function” is laughably ridiculous. Indeed, we are unaware of any culture - even among the most foreskin-friendly countries on earth - where glans visibility is considered a sign of sexual arousal. An erection is the universally recognized sign of male sexual arousal. An erection is the sign irrespective of a man’s circumcision status. And an observer can detect an erection regardless of whether the man is naked or fully clothed. Any additional “sign” would be redundant.


An anti-circumcision website explains that the foreskin, "rich in blood vessels that bring heat to the tissues ... protects the less vascular glans against frostbite." The website quotes Sir Ranulph Fiennes, an English explorer, in a book detailing his exploration of Antarctica.

" private parts were nipped and swelled up. When I mentioned this to Mike, it turned out he was having the same problem only worse, with a blistered end. He was circumcised and therefore, in effect, had one less layer of insulation. I made a note of this factor in terms of selecting future candidates for polar expeditions."

There is no apparent awareness among circumcision opponents of the implausibility of this "function."

Incidents of severe frostbite are rare. A 2009 study by Mäkinen reported that the annual incidence of severe frostbite in men in Finland was 1.6%. Men were more likely than women to suffer severe frostbite based on "employment in certain industries, high physical strain, and weekly cold exposure at work." [1]

A 2006 article in a science journal reports that a many cases of severe frostbite occur in men serving in harsh weather conditions in the Finnish military. [2] We were unable to find ANY study that mentioned frostbite of the glans or listed circumcision among the risk factors. Severe frostbite is so rare in the United States that with no standardized reporting system, it's difficult to get a definitive number on the frequency among American males.

Let's assume that the Fiennes quote is true and accurate. While it's possible that the foreskin lessened the swelling of his penis, it didn't prevent injury. And we don't know whether Fiennes wore additional protection than his partner. We don't know whether Mike spent more time outside their shelter. And even if all other factors were identical for both, the comparison involves just two men living in a rare, severe environment, and cannot be extrapolated to the general population.

Moreover, in case a man was unprotected, the foreskin would suffer the same or more serious frostbite than the glans. If you’re the one-in-a-billion man on earth who will spend months traveling on foot in Antarctica [3] - then you may benefit from having a foreskin. If you’re not a polar explorer, your glans will probably be fine as long as you’re not a long-term outdoor nudist in winter. [4]

Finally, a polar explorer is unlikely to have access to warm running water for washing. An uncircumcised man may run into hygiene issues, which would cancel any benefit of a tiny extra layer of insulation. The idea that the foreskin must be treated as sacred - because a baby may grow up to become a polar explorer lacking adequate protection from the elements, and that circumcision will be the reason why he gets frostbite - is so ludicrous that we can only laugh at this entry on the list.

[1] Mäkinen TM; "Occurrence of frostbite in the general population - work-related and individual factors"; Scand J Work Environ Health; October 2009 [2] Juopperi, Kimmo; "The occurrence of frostbite and its risk factors in adolescents and young adults"; International Journal of Circumpolar Health; 2006 [3] Modern technology is now used to travel to the Antarctic bases. [4] Melanie Lindwall Schaab of Circumcision Facts and Science is credited with this paragraph.


The fabulous foreskin delivers all-weather protection. It shields the rugged male genitals from the bitter cold of the Arctic tundra and the unrelenting heat of the Sahara desert.

Seriously, there isn't much to say about this supposed "function." Most circumcised men don't burn their glans because they aren't foolish enough to expose themselves for a significant period of time on a sunny day.

Shorts or a swimsuit will provide plenty of protection for the private parts. Nude sunbathers should check with a dermatologist regarding the use of sunblock products on certain body parts. It probably isn't a good idea to spend a long time sunbathing in the nude. You don't want to increase your risk of melanoma, particularly in the pubic region.


In the foreskin, there are lysosomes that kill bacteria. However, in spite of this fact, uncircumcised males acquire more bacterial infections than circumcised males. [1]

The foreskin also contains white blood cells. However, HIV specifically attacks white blood cells, so their presence makes a man at greater risk of contracting HIV. [1]

Several studies show that the foreskin is prone to infection. There is evidence that the warm, moist space under the foreskin becomes colonized by bacteria associated with UTIs [2], and one study shows that circumcision changes the microbiome of the glans by reducing harmful anaerobic bacteria. [3]

So it’s more accurate to look at the lysosomes as a stop-gap measure against infection, not an actual infection prevention. Lysosomes in the foreskin provide a pyrrhic benefit whose value is negated by the increased overall risk of infection. [4]

[1] For a list of studies, see Summary of Circumcision Research at

[2] Irkilata L.; "Preputial bacterial colonisation in uncircumcised male children: Is it related to phimosis?"; JPMA; 2016

[3] Liu, Cindy M; "Male Circumcision Significantly Reduces Prevalence and Load of Genital Anaerobic Bacteria"; mBio; 2013

[4] Melanie Lindwall Schaab of Circumcision Facts and Science contributed to this post.


PART 1: Protects against contamination and UTIs

We embarked on an elaborate scavenger hunt to uncover the source for this protective function. The starting point was a 2009 article posted on a popular anti-circumcision website. The article states:

“The foreskin contains muscle fibers arranged in a whorl to form a sphincter at the tip of the foreskin. The sphincter holds the foreskin protectively closed except when the child urinates and the pressure of the urine stream forces the sphincter to open, allowing outflow of the urine. Then the sphincter closes again and prevents entry of foreign matter, such as fecal material that contains bacteria. The sphincter of the foreskin keeps contaminants away from the urethra and is added protection against UTI.” [1]

So we're looking for a series of muscle fibers that act as a sphincter. The article cited a 1998 article published in a British medical journal, authored by a trio of academics whose names we recognized as scholars with a long trail of anti-circumcision advocacy. According to the authors, “The sphincter action of the preputial orifice functions like a one way valve, blocking the entry of contaminants while allowing the passage of urine.” [2]

To support this assertion, the 1998 article cited two other articles: one in a 1980 Indian medical journal, the other in a 1916 American medical journal. The 1980 article describes the structure of the foreskin, but does not indicate that the foreskin contains or functions as a sphincter or a one-way valve. Nor does the article suggest that the foreskin acts to protect the urethra from contamination, infection, or complications. [3]

The 1916 article describes the dartos fascia based on examinations of ten foreskin specimens. The author didn’t detect a sphincter, but referred to a passage from a 1902 medical book. “Woolsey remarks that the dartos fibers at the end of the prepuce are circularly arranged, forming a kind of sphincter. There was no special collection of fibers such as might be thought to indicate a sphincter in any of the specimens I examined, but the sphincteric possibilities of any part of the preputial portion of the muscle cannot be denied.” [4]

Searching the internet we were fortunate to locate a scanned copy of the 1902 Woolsey book. The key passage was hidden deep within a detailed description of the male urethra and external genitals. “At the end of the prepuce the muscular fibers are arranged circularly, forming a kind of sphincter.” The author did not indicate that these fibers provide any protective function for the urethra. Interestingly, he reported that the foreskin is responsible for inflammation and other penile complications. And he noted that some cases of phimosis “require circumcision” as the appropriate treatment. [5]

So the promised reward for our trek resembled the illusive treasure at the end of the rainbow; these sources provided no evidence that the foreskin protects the urethra against infections.

On the contrary, several studies show that uncircumcised boys have more urinary tract infections than circumcised boys. Although the foreskin can be tightly fused to the glans, bacteria, viruses, and yeast can and do infiltrate the space between the foreskin and the glans. In comparative studies, uncircumcised boys consistently have more UTI-causing microorganisms than circumcised boys. [6]

PART 2: Protects against meatal stenosis [7]

Meatal stenosis is the narrowing of the urethral opening. Estimates for the frequency of this complication vary by orders of magnitude. Circumcision opponents typically cherry-pick studies with the highest rates, and ignore others. The study with the largest sample size found about 80 cases per million in circumcised boys, and 71 per million in uncircumcised boys in the first 6 months of life. The rate is less than 0.05 % risk for boys up to three years. [8]

The cause of meatal stenosis is currently uncertain. Theoretical causes in the circumcised male include irritation from the ammonia (in urine) in the diaper, resulting in meatitis, resulting in meatal stenosis; congenital meatal stenosis resulting in meatitis; abrasions; and diet (Belman et al, 1978). However, ammoniacal dermatitis and meatitis are more common in uncircumcised males.

One study suggested that meatal stenosis occurs symptomatically in 3-8% of circumcised boys. A 2015 study found that only half of symptomatic cases will require treatment (i.e., 1.5-4% of circumcised boys may require treatment). Furthermore, severe complications of meatal stenosis are extremely rare (Godley et al, 2015).

The idea that meatal stenosis is more common in circumcised boys is based on studies like one by Robert Van Howe, a physician with an extensive background promoting an anti-circumcision agenda. Van Howe’s study lacked a sufficient number of uncircumcised boys to obtain a statistically significant result. On the other hand, one study found that applying petroleum jelly to the penis following circumcision reduced the meatal stenosis incidence from 6% to 0% (Bazmamoun, Ghorbanpour, & Mousavi-Bahar, 2008), which seems to suggest that circumcision may indeed play a role.

In any case, meatal stenosis is a simple problem to fix.

The bottom line is that the available evidence doesn’t support this “function,” as circumcised boys generally have lower rate of complications of the urethra than their uncircumcised peers.

[1] “How the Foreskin Protects Against UTI”; Peaceful Parenting; December 2009 [2] Fleiss, P, Hodges, F, Van Howe, R; “Immunological functions of the human prepuce”; Sexually Transmmitted Infections, Volume 74, Number 5, pp 364-367, October 1998 [3] “Human prepuce: some aspects of structure and function”; Indian Journal of Surgery; Volume 44: Pages 134-137, 1980 [4] “Surgery, Gynecology, and Obstetrics”; Volume 23, Number 2, pp 177-181; August 1916 [5] Woolsey, George; Applied Surgical Anatomy, pp 406-407; 1902. [6] Tuesday Topic: Circumcision Reduces UTIs Week 01; Circumcision Facts and Science; August 30, 2016

[7] Melanie Lindwall Schaab of Circumcision Facts and Science contributed to this section.

[8] El Bcheraoui, Charbel; "Rates of adverse events associated with male circumcision in U.S. medical settings, 2001 to 2010