We have all heard the myths surrounding Cleopatra, the last Egyptian queen of the Ptolemaic dynasty in Egypt. One of those myths portrays her as a woman of extraordinary beauty, capable of captivating any man. Nevertheless, the most famous of all by far is a beauty regimen that she supposedly practiced—taking baths in sour milk to achieve softer skin. While historians argue that many of these myths lack historical basis, their enduring iconic status remains undeniable, as they continue to be remembered to this day. [1]
Figure 1. Queen Cleopatra ruled Egypt for more than two decades, earning her place among the ancient world's most influential female leaders. Photo by Diego F. Parra via Pexels
The unquestionable association between Cleopatra and beauty earned her the title of the "queen of dermatology" from notable historical figures. Her influence extended to other renowned women such as Poppaea Sabina, the second wife of Roman emperor Nero, who supposedly followed Cleopatra's example and performed the same milk baths to smoothen her skin, as some ancient records suggest. This notion also inspired a movie that portrayed Cleopatra's daily bathing ritual and even today, beauty brands continue to draw inspiration from this historical practice, incorporating it into their products. [2] This brings up fascinating questions: can this old practice actually provide the desired results? Could there be a scientific explanation behind this ancient myth?
Decoding the Science Behind Sour Milk
Let us explore the connection between sour milk and its potential benefits for the skin. Sour milk is produced by the fermentation of milk, a process in which lactose, the main sugar in milk, is converted into lactic acid reaching concentrations of up to 0.97%. [3]
Figure 2. Chemical Structure of Lactic Acid [5]
Lactic acid is an alpha-hydroxy acid (AHA) which is also a component of the natural moisturizing factor (NMF) of the skin and plays a crucial role in maintaining the hydration in this organ. [4] It is widely recognized as an excellent moisturizer. However, its benefits extend beyond this. It has been demonstrated to effectively stimulate cell renewal and induce the production of collagen and glycosaminoglycans. Additionally, it exhibits a skin-lightening effect by inhibiting the activity of the enzyme tyrosinase and it also promotes ceramide biosynthesis, strengthening the skin barrier. [6,7,8,9]
Scientific studies have documented the beneficial properties of lactic acid at two specific concentrations: 5% and 12%. For instance, research involving 12% lactic acid preparations has demonstrated its ability to reduce wrinkles, enhance skin elasticity, boost hydration, and increase the number of cells in the dermis, the deeper layer of the skin, after three months of use. On the other hand, the use of a 5% lactic acid solution showed favorable changes limited only to the epidermis, the top layer of the skin. Furthermore, a study confirmed that even at lower concentrations, such as 2%, lactic acid provides skin benefits, including a reduction in comedones. [6] These findings suggest that the ancient myth of bathing in sour milk might have had a scientific basis after all, despite the lack of understanding or awareness at that time.
Lactic acid is now commercially available and is used to address issues like acne, skin aging, and discoloration. Dermatologists utilize high concentrations of lactic acid (>20%) as chemical peels to treat various conditions like calluses, acne, and photoaging. Moreover, it has also been incorporated into nonprescription washes and moisturizers, typically at concentrations of 4% to 6%, with claims of effectiveness against skin aging.
Figure 3. Chemical peeling is a procedure used for the improvement of the skin’s appearance. It involves the application of a chemical agent to the skin, which selectively destroys the outer layers (epidermis and/or dermis). Photo by Anna Shvets via Pexels
Cautionary Notes and Side Effects
However, it is important to note a significant concern associated with the use of alpha hydroxy acids like lactic acid, which is the potential to increase the skin's sensitivity to UV radiation. The specific side effects of AHA therapy can vary based on the type and concentration of the ingredients utilized, but the most common symptoms are burning, rash, changes in pigmentation, peeling, and itching, therefore is always important to consult with professionals for personalized recommendations. [4]
Conclusion
In conclusion, Cleopatra's beauty practices continue to inspire and intrigue to this day. While the veracity of her legendary milk baths may forever remain a mystery, we now know that it has a scientific explanation since the lactic acid in sour milk has beneficial effects on the skin such as exfoliation, moisturization, and antioxidative properties. Nowadays, lactic acid is widely recognized for its therapeutic applications in treating various skin conditions and is commonly incorporated into skincare products. Although we may never know the exact details of Cleopatra's regimen, the knowledge we have now about sour milk and lactic acid only adds credibility to the continuing fascination for her beauty practices.
References
[1] Kendall, B. (2018) The forum - who was the real Cleopatra? - BBC Sounds, BBC News. Retrieved May 18, 2023 from https://www.bbc.co.uk/sounds/play/w3cswpsp.
[2] Ursin, F., Steger, F., & Borelli, C. (2018). Katharsis of the skin: Peeling applications and agents of chemical peelings in Greek medical textbooks of Graeco‐Roman Antiquity. Journal of the European Academy of Dermatology and Venereology, 32(11), 2034–2040. doi:10.1111/jdv.15026
[3] Cheung, P. C. K., & Mehta, B. M. (2015). Chemical Composition of Milk and Milk Products. In Handbook of Food Chemistry (pp. 511–554). Berlin, Germany: Springer Berlin, Heidelberg.
[4] Baki, G., & Alexander, K. S. (2015). Introduction to cosmetic formulation and Technology. John Wiley.
[5] National Center for Biotechnology Information (2023). PubChem Compound Summary for CID 612, Lactic Acid. Retrieved May 18, 2023 from https://pubchem.ncbi.nlm.nih.gov/compound/Lactic-Acid.
[6] Algiert-Zielińska, B., Mucha, P., & Rotsztejn, H. (2018). Lactic and lactobionic acids as typically moisturizing compounds. International Journal of Dermatology, 58(3), 374–379. doi:10.1111/ijd.14202
[7] Smith W. P. (1996). Epidermal and dermal effects of topical lactic acid. Journal of the American Academy of Dermatology, 35(3 Pt 1), 388–391. https://doi.org/10.1016/s0190-9622(96)90602-7
[8] Lee C. M. (2016). Fifty years of research and development of cosmeceuticals: a contemporary review. Journal of cosmetic dermatology, 15(4), 527–539. https://doi.org/10.1111/jocd.12261
[9] Spada F, Barnes TM, Greive KA. Skin hydration is significantly increased by a cream formulated to mimic the skin’s own natural moisturizing systems. Clin Cosmet Investig Dermatol. 2018;11:491-497 https://doi.org/10.2147/CCID.S177697