If a body wash falls in the forest, is it gentle on the microbiome?

Well, I guess I am happy Dove is interested in the microbiome. My exposure to Dove's thinking on the microbiome started with an ad that was shared with me by Christine Parks.

The ad claims that Dove is gentle on the microbiome.  OK.  I am not sure I get what that means completely.  But I think they are saying "Our product does not mess up your microbiome".  I guess this could be good for some people if it were true.  But for others, maybe you want to mess up the microbiome.  Regardless, I would love to see data, if it exists, behind such a claim because my guess is that any body wash affects up the microbiome in many ways.

So, if they were not going to show evidence for this claim, I wondered, what are the ingredients of this Dover product? Fortunately the company provides them readily: https://www.dove.com/us/en/washing-and-bathing/body-wash/deep-moisture-body-wash.html. And here they are:

• Water (Aqua), 
• Cocamidopropyl Betaine, 
• Sodium Hydroxypropyl Starch Phosphate, 
• Lauric Acid, 
• Sodium Lauroyl Glycinate, 
• Sodium Lauroyl Isethionate, 
• Hydrogenated Soybean Oil, 
• Glycine Soja (Soybean) Oil, 
• Sodium Chloride, 
• Glycerin, 
• Fragrance (Parfum), 
• Phenoxyethanol, 
• Guar Hydroxypropyltrimonium Chloride, 
• Stearic Acid, 
• Citric Acid, 
• Sodium Isethionate, 
• BHT, 
• Tetrasodium, 
• Iodopropynyl Butylcarbamate (IPBC)

This last one, Iodopropynyl Butylcarbamate (IPBC), is interesting since there is a paper discussing its effect on the microbiome. See "Effect of cosmetic chemical preservatives on resident flora isolated from healthy facial skin". They report "MTI and IPBC displayed the strongest effect on all tested strains (MICs ≤0.01%), followed by EHG and MP (MICs ≤0.3%), and finally PE with the weakest effect (MIC ≤1%)."  IPBC apparently is a known antibacterial and anti fungal agent.  Unclear how that being in the product is consistent with being gentle on the microbiome.

BHT is also interesting as it has been known as an antimicrobial for a long time (e.g., see this 1980 paper). It is used widely as a "preservative" but one of the ways it works as a preservative appears to be that it is anti microbial. 

Phenoxyethanol is also an antimicrobial.  See for example this where they report things like:

The study reveals that the six preservatives-Phenoxyethanol, Methyl paraben, Propyl paraben, Sorbic acid, Potassium sorbate and Sodium benzoate shown antimicrobial activity with the three test organisms at various concentrations and time periods.

My guess is many of the other ingredients can also affect the microbiome.  This would not really be surprising as lots of things affect the microbiome.  So, sorry Dove, but just saying your product is "gentle on the microbiome" just does not cut it for me.

I decided to see if I could find out anything else about Dove's claim of being gentle on the microbiome so I did the usual thing and Googled "Dove microbiome" and found some of their material on the microbiome.  And I guess I could say I was pretty disappointed. For example see this:Introducing your skin’s microbiome – Dove Nothing there providing data on just how gentle Dove really is or is not on the sin microbiome.  And in addition there was a statement I was not so fond of:

"Think of it as an invisible eco-system that lives on the skin that’s working to help keep it healthy and in good condition. "

Umm -- no -- no evidence for this.  The microbes on your skin appear to mostly be working for themselves.  Some of the time they are harmful. Some of the time they are helpful.  Some of the time they are neither.  But they are certainly not "working" to keep skin healthy.

So - it seems like Dove wants to get in on the microbiome hype.  I guess I am glad they are interested in the microbiome.  But they cannot just make claims about things like "being gentle" on the microbiome without evidence.  Especially when their ingredient list contains a collection of known antimicrobial chemicals.