Sun-Kissed or Stressed? The Science Behind Self-Tanner

Skin professionals already know that traditional tanning puts one at risk for sunburn, premature aging, and skin cancer. Most dermatologists will warn that there are absolutely no safe tans involving ultraviolet A or B rays.1 Tanning beds have also been proven to be detrimental and harmful to users over time. In this light, it has been widely accepted that the myriads of self-tanners on the market are the best and safest alternative for those wanting that sun-kissed glow; however, that might not always be completely true.

NATURAL TANS
The natural tanning process is skin’s defense mechanism against ultraviolet radiation from sunlight. When exposed to sunlight, ultraviolet rays trigger melanocytes in the epidermis to produce melanin, the pigment that darkens skin. This process, called melanogenesis, converts the amino acid tyrosine into melanin, which is then transferred to surrounding skin cells (keratinocytes) to absorb and scatter ultraviolet radiation, protecting DNA in skin cells. The tan gradually deepens with continued exposure but fades as skin cells turn over. A similar process occurs with self-tanners but on a chemical and surface level.

FUNCTION
The key active ingredient in providing a temporary tan is called dihydroxyacetone (DHA) and is a simple carbohydrate derived from synthetic or natural sources such as beets or sugar cane. In some cases, a similar ingredient, erythrulose, is used. This is the chemical mechanism behind self-tanners (as well as spray tans) that artificially darken skin.6
Topical dihydroxyacetone formulations can come in lotions, gels, mousses, sprays, and wipes. When dihydroxyacetone is applied, it reacts with the amino acids in the stratum corneum, forming a pigment called melanoidin which darkens skin temporarily, thus imitating the natural tan created by melanin. Earlier studies of dihydroxyacetone tanning were thought to act more like “staining,” but further research has concluded the reaction is more an oxidative glycation or oxidative stress due to the Maillard reaction. 5
The Maillard reaction also occurs whenever food is cooked at high temperatures (like toasting, grilling, or caramelizing). Tanning reaction takes place from two to four hours after dihydroxyacetone application, continuing for up to 72 hours. This chemical reaction is also the reason self-tanners have a distinctive odor once applied.6,7

Glycation is the covalent attachment of a sugar to a protein, lipid, or nucleic acid molecule. A form of nonenzymatic glycation accompanies a Maillard reaction. Glycation can directly lead to stiffening of collagen and elastin fibers and is responsible for what many call “sugar sag” in many diabetics’ skin.3 Some medical professionals concluded that tanning lotions with DHA do appear safer than sunbathing or tanning beds as long as the oxidation occurs on the top layer of skin.2 A report released by the FDA theorized that “although dihydroxyacetone was previously thought to be limited in penetration to the dead outer layer of the skin, that about 11% of the applied dihydroxyacetone penetrates into the living cells of the epidermis and dermis.”6

SECONDARY INGREDIENTS & ADVERSE REACTIONS
After the primary active ingredients dihydroxyacetone or erythrulose, standard humectants, occasional parabens, coloring agents, fragrances, and preservatives will be found in most sunless tanners. If a DHA-formulated lotion or cream is used, dermatologists suggest avoiding one that has fragrances, preservatives, alcohols, or other unnecessary ingredients that could potentially irritate sensitive skin or cause an allergic reaction.

For example, a mousse self-tanner will have a higher alcohol content, allowing it to dry faster yet requiring additional moisturizer. Other products may contain excessive perfume to mask the oxidative scent or additional dyes to show application areas. When possible, choose products with more organic and naturally derived ingredients.

Furthermore, spray-tan versions have resulted in accidental inhalation and respiratory issues. One should always use proper protective gear and have excellent ventilation when in use. “Reported side effects from dihydroxyacetone containing spray tans include rashes, cough, dizziness, and fainting.”6
As with all topical products, it is up to the consumer and their skin professional to research the chemicals they are using on their skin and check for adverse reactions or allergies. Considering the pending and sometimes complicated scientific studies on DHA, medical professionals recommend the safest self-tanning products to be cosmetic bronzers, as they don’t actually change the skin chemistry but simply layer color on top of skin. If a bronzer is not preferred, using tanning gels and sprays is still a much safer alternative to sun exposure or tanning beds, but there are still some risks and considerations.

MINIMIZING OXIDATIVE STRESS
Some studies have shown that dihydroxyacetone can lead to the production of free radicals when exposed to sunlight after application, which could contribute to additional oxidative stress and premature skin aging if protective sunscreen isn’t used. It is worth noting that these studies used higher concentrations than found in the typical consumer product.3,4
“Using the RSF method, three different self-tanning agents were analyzed and it was found that in dihydroxyacetone treated skin more than 180% additional radicals were generated during sun exposure with respect to untreated skin. For this reason, the exposure duration in the sun must be shortened when self-tanners are used and photoaging processes are accelerated.”4,6

Tips to Avoid Oxidative Stress
Use antioxidant-rich skin care: Apply an antioxidant serum (like vitamin C or E) before using tanning products. Antioxidants can help neutralize some of the free radicals produced by DHA.
Avoid sun exposure after application: Since DHA creates more free radicals under ultraviolet exposure, it’s best to avoid sun exposure or apply a broad spectrum ultraviolet A and B blocker after tanning product application.
Be aware of unregulated ingredients in do-it-yourself products. Some over the counter or DIY tanning products may contain ingredients not well-regulated or thoroughly tested, increasing the risk of side effects like irritation, rashes, or even more serious skin reactions.

Always inform clients that tanning gels and sprays rarely provide protection against ultraviolet radiation. Some users may mistakenly believe their tan is a barrier against sun damage, which can lead to sunburn and an increased risk of skin cancer if sunscreen isn’t used.
Responsibility lies in the hands of skin professionals to do their due diligence and research all products they recommend to their clients that may potentially cause harm and advise them to the best of their knowledge.
Self-tanners are still overall less harmful than direct ultraviolet A and B sun exposure or tanning beds, but precautions must be taken when using dihydroxyacetone or erythrulose to avoid further glycation and oxidation damage when outdoors. Dermatology feedback on the extended safety of using dihydroxyacetone varies. Earlier published medical interviewees indicated they believed the chemical reaction to be nothing more than skin staining, while more recent research showed direct correlations to skin damage resulting in oxidative stress from dihydroxyacetone formulations and sun exposure. Further research needs to be done to understand dihydroxyacetone’s full impact on skin, and in the meantime, it is up to skin professionals to stay on top of the research and continue making informed choices about client care.

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Rachelle Dupree has over 20 years of experience in marketing, media, communications, and design. She studied with a Denver-based herbalist and naturopath for four years, combining her marketing knowledge with her love of natural remedies and skin care. She currently contracts as a marketing and communications director for Vivoderm Natural Skincare and various design clients.