Wikipedia:Reference desk/Archives/Science/2021 July 26

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July 26

Is soap harmful to most of cells of living things?

According to some health education videos such as [1], amphiphiles from the soap or detergents can break up the lipid bilayer envelope of viruses (e.g. coronavirus). On the other hand, cell membranes consist of lipid bilayers which can also be broken up by amphiphiles from the soap in my opinion.

So if someone has swallowed a lot the soap, what kind of damage will it lead to with regard to the cells in the body?

Do any amphiphiles exist in food? How about those molecules, if any, in food affect the cells and viruses in the body? - Justin545 (talk) 04:35, 26 July 2021 (UTC)

That video is not entirely accurate. In the case of most viruses it is not physically possible for soap molecules to get close enough to disrupt the lipid bilayer - this is more commonly observed in bacteria. And the amphiphiles (more typically called surfactants) certainly wouldn't form 'bubbles' (more typically called micelles) around the genetic material, as that's water-soluble. Any anti-viral benefits of soap would mostly be due to the physical removal of the virus, rather than the virus's destruction.

Regarding the harmful effects of ingested soap, our cells have an outer membrane of cellulose, which is highly resistant to oil, water and soap alike - this is why we can wash our hands without injuring ourselves. Any adverse health effects would be due to the soap's alkalinity, and chemical incompatibility with the digestive system, rather than due to its surfactant properties; the severity would depend whether you're talking about traditional soap, which is made from the reaction between fat and alkali, and has an alkaline pH around 9-10, or syndet bars, e.g. Dove, which have a more neutral pH. The former would be more harmful, but neither of them would do you any good.

Phospholipids are naturally-occurring surfactants which are the main component of cell membranes - for instance, lecithin, which is found in eggs, soy beans, and sunflower seeds, and is commonly used as a food additive. Vegetable-based emulsifiers, e.g. sorbitan oleate and glyceryl stearate, are also commonly used as food additives, and are known to be benign. Rhythdybiau (talk) 16:15, 26 July 2021 (UTC)

Our cells don't have an outer layer of cellulose; those are plant cells. Your skin specifically has an outer layer known as the stratum corneum which protects your skin from many harmful things, but not all of your cells have such a covering. --Jayron32 17:51, 26 July 2021 (UTC)

Good point, my mistake. Rhythdybiau (talk) 18:08, 26 July 2021 (UTC)

" it is not physically possible for soap molecules to get close enough to disrupt the lipid bilayer", what is the reason for that? Is it due to the outer layer of cellulose that separates soap molecules from the lipid bilayer? - Justin545 (talk) 03:34, 27 July 2021 (UTC)

Yep, I once thought that there should be something in food (such as surfactants lecithin and emulsifiers you have mentioned) that may also disrupt lipids. It makes me wonder why lipid bilayers of cells don't seem to be affected by surfactants and emulsifiers in food ... - Justin545 (talk) 04:12, 27 July 2021 (UTC)

The viral envelope that some viruses have, including the coronaviruses, is a lipid bilayer that is dissolved by soap, which then disrupts the next layer, the capsid, making whatever remains of the virus particle non-infectious.^[2][3][4] It is difficult to make a fully general statement of the effect of soap on living cells. For example, although not a good idea, you can wash a fertilized bird egg (which is a single cell) with mild soap and still expect it to hatch. Ingesting a considerable amount of soap can do severe damage to the lining of the digestive tract and is potentially lethal.^[5][6][7]  --Lambiam 17:09, 26 July 2021 (UTC)

"a lipid bilayer that is dissolved by soap, which then disrupts the next layer, the capsid", do you mean that soap can also disrupt the capsid of viruses? But capsids consist of protein, don't they? I thought soap mainly disrupts lipids ... - Justin545 (talk) 03:54, 27 July 2021 (UTC)

The capsid of coronaviruses does not have a convex shape and is not particularly strong, unlike that of some other viruses that don't have a lipid envelope protecting it. It is more like the skin of a long sausage of RNA tightly coiled up inside the envelope, as shown in the central image of three here. When a cell is infected by a coronavirus virion, the entire nucleocapsid is delivered, wrapping and all. The wrapping disintegrates spontaneously once the lipid envelope is gone; otherwise the payload after delivery into an infected cell would not be unwrapped and remain harmless. Of course, the spike proteins are anchored in the lipid envelope, so even if the capsid is not disrupted the virions lose their ability to infect cells when the envelope is destroyed.  --Lambiam 08:31, 27 July 2021 (UTC)

Fair enough. Capsids of coronaviruses are not like what I expected. And coronaviruses should be a kind of virus, not viroid, right? Did I miss something again? - Justin545 (talk) 15:18, 27 July 2021 (UTC)\

I meant "virion", now corrected.  --Lambiam 15:50, 27 July 2021 (UTC)

Indeed, it's not easy to make a general statement of how living cells would interact with soap. I think there are some cells with special abilities or structures to resist the damage the soap would bring. So let's temporarily forget those special types of cells (e.g. plant cells, cells in the stomach, cells of creatures that live in extreme environments, etc.) and focus on cells with vanilla flavor, how would soap affect them? Are the cells in question vulnerable to amphiphiles in soap? - Justin545 (talk) 15:18, 27 July 2021 (UTC)

So, everyone's bodies make bile acids, which are detergents—their purpose is, as detergents, to emulsify ingested lipids, which is necessary for them to be absorbed from the digestive tract. And as Bile acid § Bile acids and colon cancer tells you, there's suggestive evidence bile acids are cytotoxic, with this being a possible reason behind high-fat diets being linked to higher rates of colon cancer. --47.155.96.47 (talk) 01:53, 28 July 2021 (UTC)

Right, I've heard that high-fat diets could cause colorectal cancer, which I'm trying to avoid. And some cells in the digestive system still seem to survive under bile acids, which makes me wonder what is the reason that those cell membranes do not get disrupted after the contact with the digestive fluid ... - Justin545 (talk) 06:30, 28 July 2021 (UTC)