With the rising concerns of UV exposure more people are being drawn into using self-tanning products to help achieve that glowing look. It’s therefore no surprise that the market for self-tanning products is constantly growing, with a predicted expected annual growth rate of 4.5% from 2022-2030 .
Self-tanning products can be found with diverse formulations to provide the customers with a variety of hydrating and nourishing effects. Despite the different formulations, all products have one ingredient in common: Dihydroxyacetone (DHA).
DHA is the active ingredient in self-tanning products and is responsible for giving your skin that golden glow. This chemical is a 3-carbon sugar which can be derived through the fermentation of glycerine or naturally from plant sources such as sugar beets and sugar canes . In 2021, the Scientific Committee in Consumer Safety (SCCS) confirmed, after conducting safety evaluations, that the maximum concentration of DHA allowed in self-tanning products is 10% in the EU . The highest concentrations will provide darker tans, but how exactly does DHA work?
DHA acts on the stratum corneum where the cell's life cycle ends. These cells lack organelles but contain high levels of keratin, which in turn contain amino acids that DHA can bind to. Once bound, it carries out a chemical reaction known as the Maillard Reaction . During this reaction, several steps lead to the formation of the final brown polymer called melanoidin, which is responsible for the tan . Melanoidin stays fixed to the stratum corneum until natural shedding of dead skin cells occurs. This gives the tan a lifespan of 5-7 days . Occasionally, streaky, patchy, and uneven results may be observed which can be a result of poor formulation and insufficient skin preparation prior to application, so how can this be solved?
The patchy effect is due to the presence of thicker layers which contain higher amounts of amino acids that DHA can bind to. This results in a higher concentration of melanoidin formation in those areas. Exfoliating the skin prior to the application will remove any excess dead skin cells to ensure a more even application. 
Research has found that altering the pH of the skin can change the appearance of the melanoidin produced. The normal pH of the skin is around pH 5, this can also be altered due to the use of other cosmetic products. It was found that a pH level of around 6 results in more brown-pigmented melanoidin unlike more acidic pH 4 which results in yellow-pigmented melanoidin . Formulations have developed to include polymers which act as delivery systems to control the pH at which DHA is released ensuring the best result. 
All in all, the advantages of self-tanning products make up for the risks of UV tanning. Despite this, it is important to remember that these products do not replace sun protecting products. The continuous research into the chemical and biological properties of the product allows for ongoing formulation improvements to provide the best UV-free glowing tan.
FUN FACT: The Maillard reaction is also responsible for browning your cookies in the oven!
 Self-tanning Products Market Size, Share & Trends Analysis Report By Product (Lotions, Gels), By Application (Men, Women), By Distribution Channel (Online, Supermarkets & Hypermarkets), And Segment Forecasts, 2022 - 2030
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