Modern soaps vs. skin microbiome

146 viewsBiologyOther

So I’ve seen quite a lot on the internet recently (past one or two years), videos of people abandoning different forms of soap for different situations, but usually for the purpose of “restoring the body’s natural microbiome.” In many of their anecdotal claims, they’ll say things like “it cured my dandruff” or, “I don’t have psoriasis anymore”, and so on, and how their bodies come about a homeostasis of some sort. I tried it out, and while my skin cleared up, my dandruff slowly became worse over time.

I’ve also read (just now) a lot of posts here describing both the prevalence of lice in the B.C.-1700s until regular shampooing became a thing, and how soaps generally remove bacteria through mechanical means rather than outright kill them.

So I’m hoping for more than one explanation here:

• Is anti-bacterial soap a marketing myth, and “organic” soaps are just fine despite not being “anti-bacterial” because the mechanics are the same?

• Is body soap/bar soap necessary if you’re rinsing/showering with hot water daily and washing hands with soap? If so, how can I determine an appropriate washing/soaping frequency for maintaining effective hygiene for *all* parts of the body, genitals and rectum included without harming my skin?

• Does soap affect larger particles of fecal matter the same way that it affects microscopic organisms (mechanically sticking to both lipid and water and carrying away due to surface tension of water), or does it sanitize the fecal matter and some of it remains left behind or something else entirely?

• Bar soaps harbor lots of bacteria, but so does my skin and body hair, so to use or not to use?

In: Biology

4 Answers

Anonymous 0 Comments

>• Is anti-bacterial soap a marketing myth, and “organic” soaps are just fine despite not being “anti-bacterial” because the mechanics are the same?

“Anti-bacterial soaps” are soaps that have had additional anti-bacterial agents added. Most soaps primarily remove bacteria from you (there’s some interference with bacterial cell membranes, too, but it’s not the main effect). Antibacterial soaps have a chemical (usually benzalkonium chloride) that actively kills bacteria. It’s very much not a myth, though most people agree that it doesn’t really do anything. The US Centers for Disease Control (CDC) officially say that antibacterial is no more effective and preventing disease than normal soap, and the FDA says that it might have some stuff in it that’s not good for you.

>• Is body soap/bar soap necessary if you’re rinsing/showering with hot water daily and washing hands with soap? If so, how can I determine an appropriate washing/soaping frequency for maintaining effective hygiene for all parts of the body, genitals and rectum included without harming my skin?

Running hot water over you will leave most oils in place. A lot of smelly compounds are in the oils, though. Removing the oils is also what’s bad for your skin, since removing the oils makes you skin dry out (since among other things, the oils keep the moisture inside your skin).

How often do you need to do it for “effective hygiene”? Only trial and error can tell. And it’ll vary with conditions – you need to wash far more often if you’re working outside in the heat all day than if you’re sitting in an office or going on easy walks when it’s cool. You’ll know you aren’t washing enough because you’ll start getting sores and other grody stuff. Beyond that, it’s really a matter of how the people around you feel about your smell.

I know someone who basically never washes with soap, just shampoos her hair once a week and washes with hot water and a wash cloth. To be honest, she does smell a little of BO all the time, but it’s not a big deal (please do note that this is anecdotal and should not be used as life advice).

The Romans often did not use soap in their baths; instead, they would coat their skin in oil and then use a scraper to scrape away the oil, taking away dirt with it (the scraper was called a *strigil*). In some places, instead of using shampoo, it’s common to work ~~soap~~**oil** into your hair and then remove it with a very fine comb, on the same principle. Soap is very *good* for getting clean, but it’s not the only way.

>• Does soap affect larger particles of fecal matter the same way that it affects microscopic organisms (mechanically sticking to both lipid and water and carrying away due to surface tension of water), or does it sanitize the fecal matter and some of it remains left behind or something else entirely?

The first one. Normal soap doesn’t sanitize much. As I said, it does interfere with bacterial cell membranes, but that’s not the main thing it does (which is to interfere with bacteria sticking to you).

>• Bar soaps harbor lots of bacteria, but so does my skin and body hair, so to use or not to use?

Fun fact: liquid soap also harbors lots of bacteria much of the time. But usually less than soap bars, and that doesn’t really answer the question.

The first part of the answer is that most of the bacteria on your soap bar got there because they were on your body in the first place and rubbed off onto the bar. The second part is that those soap-bar bacteria are going to have a rough time sticking to you. The third part is that while there are some bacteria there, the surface of a soap bar isn’t a great place for bacteria to live. There isn’t much food there, the soap interferes with cell membranes, it’s hard for the bacteria to move around, they have difficulty communicating with their bacterial buddies. It’s not like the surface of Venus, but it’s not a fun place.

The CDC officially takes the position that bar soap and liquid soap are equally effective.

**EDIT** a couple mistakes

You are viewing 1 out of 4 answers, click here to view all answers.