Alkaline water for your skin?
Nonsense!
Your skin likes it neutral to mild acidic.
Alkaline water is water that has a pH of higher than 7, supposedly giving the buyer numerous health benefits. There is no empirical backing, a.k.a. pseudoscience. A practitioner who promoted alkaline water was sent to jail for 3 years in 2017 for practicing medicine without a license. Well done FDA!
The physiologic role of an acidic skin surface was thought to be just a defense mechanism against invading organisms. More recently, it has been shown that key enzymes involved in the synthesis and maintenance of the skin barrier are impacted by pH. For example, in the stratum corneum, two important lipid-processing enzymes, β-glucocerebrosidase, and acidic sphingomyelinase, have pH optima of 5.6 and 4.5, respectively. Lipid processing enzymes are key to building a healthy skin barrier.
Also, atopic skin (atopic dermatitis is one of the most common eczema types) seems to have higher pH values (more alkaline) in areas corresponding to more intense itching and dryness.
For people buying bicarbonate-based deodorants because they are “natural”, be warned that skin irritation and even fungal infection may follow. I prefer to fight bad, sweaty smells using a deodorant that contains aluminum zirconium octachlorohydrex glycine (C2H8AlClNO4Zr). This chemical (non-natural, I know) absorbs water and forms a temporary “plug” that prevents sweat from leaving the pores. It’s considered safe when used below 20%, and I have used it without irritation for several decades. I am not worried about the aluminum in it because my body is equipped to deal with small amounts of aluminum, which is present in tap water anyway.
Name dropping: If you search “pseudoscience” on Wikipedia, you’ll find Silvio Funtowicz and Jerry Ravetz!
Hannah
Matousek JL, Campbell KL, Kakoma I, Solter PF, Schaeffer DJ. Evaluation of the effect of pH on in vitro growth of Malassezia pachydermatis. Can J Vet Res. 2003 Jan;67(1):56-9. PMID: 12528830; PMCID: PMC227028.
Ali, SM and Yosipovitch, G. (2013) Skin pH: From Basic Science to Basic Skin Care. Acta Derm Venereol, 93: 261–267. doi: 10.2340/00015555-1531. PMID: 23322028.
See also https://quackwatch.org/related/dsh/coral2/
Natural Deodorants vs. Anti-Perspirants. Is Aluminum as bad as THEY say it is?