Deodorant Innovation: Opportunities and emerging technologies

In this blog, our Senior Innovation Consultant, Dr Katerina Steventon, looks at emerging industry trends in deodorant innovation and current research taking place, whilst addressing the affect body odour has on consumers’ mental health – with insights from our industry and research partners.

Deodorants, applied to the underarm (axilla), manage those bacteria responsible for our distinctive body odour. Deodorant formulas contain deodorizing technologies that can either prevent bacterial growth or reduce the number of bacteria in the axilla. Not only the bacteria on the skin, but especially the species living in the sweat glands and hair follicles play a pivotal role in malodour formation. Deodorants work in tandem with antiperspirants (technologies that reduce the release of sweat from the sweat glands) and also have a deodorizing effect, by inhibiting bacterial growth due to a lower pH and reduced moisture. People usually want to reduce sweat – in addition to the ‘no odour’ effect of a deodorant – to prevent sweat staining on clothes. Clothing contributes to odour intensity since secretions, skin debris, sebum, odorous volatiles and microorganisms are transferred from the body to the garment. The odour intensity is potentially more intense in the fabric substrate than in the axillae[i]. The ‘primary odour’ originates in the axilla itself[ii].

Consumer concerns: feeling self-conscious and isolated

Body odour is a serious and frustrating concern that often leads to discomfort and unease in many people and thus presenting an unmet need and a large commercial opportunity. Embarrassment about body odour can also lead to people feeling isolated. Over one third of survey participants said the fear of smelling unpleasant had ‘held them back from talking to or hugging someone and being offensive by the smell of body odour or musty clothing’. This made them feel unhappy and unattractive, self-conscious, and dirty. Malodour can affect romantic relationships and result in social isolation avoiding close proximity with others[iii]. Unique body odour may become unpleasant due to hormonal fluctuation, excessive sweating or poor hygiene. However, sudden changes typically caused by the environment, medication or diet, if persistent can be a sign of an underlying health condition.[iv]

The axillary microenvironment – a hotspot for odour formation

The factors that cause people to sweat are e.g., an increased body temperature due to physical activity, or fever to regulate the body temperature by evaporative heat loss. Fresh sweat, released by eccrine sweat glands for thermoregulation, is an odourless fluid

containing mainly water and salt electrolytes (Na⁺, K⁺, Ca²⁺, Mg²⁺, Cl^–, HCO3^–, lactate, urea and ammonium). Stress-induced sweating is part of an ancient evolutionary response to a threat and plays an important role in our non-verbal communication. Sweating due to emotional or psychological stress occurs in the armpit, soles, palms and forehead, secreted by apocrine sweat glands. Apocrine sweat consists of lipids and proteins, which metabolized by skin bacteria cause the characteristic body odour. The odour precursors consist of long-chain fatty acids, fatty acids bound to amino acids, sulphur containing amino acids, vitamins and steroids.

When skin microbiota present in the axilla metabolise secretions from eccrine, apocrine and sebaceous glands – sebum and sweat lipids and proteins, the malodour evolves.

The underarm areas add up to 200 cm², which is only about 1% of the whole-body surface. The armpit has ideal conditions for bacterial grow – it is a warm, moist environment with higher pH and nutrient rich environment by sweat and sebum glands that ensures continuous colonisation by abundant and diverse bacteria.[v] The malodour depends on the microbial community composition and the quality and quantity of the secretions impacted by age, gender, cosmetics use, diet, climate, stress, hygiene.

Malodour-causing bacteria

In 2013, a Belgian academic group studying a typical axillary microbiome in healthy people have shown interpersonal, intrapersonal and temporal diversity of the human axillary microbiota. They characterised two important clusters in the axillary region, with Staphylococcus and Corynebacterium as abundant species. In women, Staphylococcus and in men Corynebacterium formed the predominant clusters.

“Prof Andrew McBain and Dr Gavin Humphreys from the University of Manchester analysed synthetic and natural fabric cuts of clothing from the underarm for a BBC study. Exploring the microbiome of the textile by next-generation sequencing, they found several hundred different types of bacteria inhabiting the armpit. The most common included staphylococci and corynebacteria which, among other organisms, have been associated with axillary malodour.”[vi]

The axillary microbiota, unique to each individual, shows left-right asymmetry in about half of the population and is relatively stable. The use of deodorant impacts the species diversity.[vii] At the same time, Unilever carried out culture-based microbiological research to confirm that resident axillar microbiota consists mainly of Gram-positive bacteria of the genera Staphylococcus, Micrococcus, Corynebacterium and Propionibacterium. Among the molecular classes implicated in malodour are short- and medium-chain volatile fatty acids, 16-androstene steroids and, most recently, thioalcohols. Corynebacterium were thought to be the primary causal agents of axillary odour.[viii] Since then, 158 strains of 24 species were identified in health axilla: the majority belonged to Corynebacterium (68.9%), Staphylococcus (21.6%), Micrococcus and Candida albicans.[ix] Further research confirmed that both corynebacteria and staphylococci contribute to malodour.[x] Malodorous volatiles can be of steroid-, sulphur- and volatile fatty acid origin. Sulphurous compounds from apocrine secretion have a low olfactory threshold and contribute greatly to the axillary odour, giving it its typical onion-like and musky scent. Microbial degradation of eccrine sweat, keratinocyte debris and sebum lead to the production of short-, medium-, and branched-chain volatile fatty acids that known for the acidic notes or promoting microbial growth (acetic acid, propionic acid, isovaleric acid). Degradation of steroids, previously strongly implicated in axillary malodour, may not be as significant as originally thought.[xi] Reduced use of deodorant and antiperspirant can result in an increased bacterial density similar to individuals who do not use any product. Use of antiperspirants and deodorants long-term and stopping for two or more days, favours presence of Staphylococcus, whilst no product use favours Corynebacterium. Differences in product use exert striking differences in the richness of bacteria living in armpit communities.[xii]

R&D trends and innovation

Innovation in deodorants targets to inhibit body odour altogether. Whilst deodorants work by inhibiting or killing underarm bacteria in order to prevent malodour, given that only a small number of bacteria are actually responsible for malodour, there is an opportunity to create new generation of deodorants that specifically target these species.

In 2018, NBIC Academic Partners, the University of York and University of Oxford identified part of the molecular process that creates malodour. The research confirmed that the species playing a major role in malodour production is Staphylococcus hominis, creating its most pungent component. The key smelly component is the sulphurous volatile thioalcohol, 3-methyl-3-sulfanylhexan-1-ol (3M3SH), produced by microbial conversion of its odourless precursor S-Cys-Gly-3M3SH. The conversion occurs via a transport protein, which allows bacteria to recognize and absorb this odourless compound secreted in sweat. A blueprint of the protein’s molecular structure allowed the researchers to learn how it works and how to target it[xiii][xiv]. In collaboration with Unilever (2020) and building on their previous findings about S. hominis, researchers at University of York discovered a “B.O. enzyme” responsible for the pungent malodour. Solving the structure of this enzyme has allowed them to understand the molecular pathways in odour production. This research on “The Molecular Basis of Thioalcohol Production in Human Body Odor” published in Scientific Reports will enable Unilever to develop targeted inhibitors to stop malodour production without disrupting the armpit microbiome.”[xv][xvi]

“It was a huge shock to discover that only a few Staphylococcus bacteria, including S. hominis, caused odour.” says Dr Gordon James, Science Leader in Microbiology (Deodorants), working for Unilever. The team has gone a step further by identifying a unique ‘BO enzyme’ found only within these bacteria and solely responsible for the distinctive note of armpit odour. “This is the biggest breakthrough yet from our successful collaboration with the University of York on the origins of BO. The discovery of a key odour-forming enzyme in a select few bacteria, which evolved tens of millions of years ago, is a real eye-opener.”[xvii] Dr Gordon captured the research highlights in an Instagram podcast[xviii]

New academic research into axillar malodour brings about a few novel and exciting strategies to eliminate/inhibit the “bad bugs” and apply/stimulate the “good bugs”. These entail armpit bacterial transplantation i.e. replacing the malodour-causing microbiome with a non-odour-causing microbiome, direct application of probiotics/non-odour-causing bacteria and/or selective steering of the microbiome with prebiotics, small molecules or plant extracts. All can be successful in help to improving the underarm odour but validating these scientific approaches clinically is required.[xix]

New deodorant technologies: from mass market to indie brands

There is a growing interest in exploring the impact of personal care products on healthy skin microbiome as well as an increase in consumer expectations in terms of natural, sustainable and environmentally friendly products with high efficacy. Considering rising demand for safe and effective mass market deodorants and the US Food and Drug Administration‘s expressing concerns over the antibacterial and antifungal agent Triclosan, Beiersdorf substantiated the antimicrobial efficacy and prevention of malodour formation (trained sniffers rating after 24 hr and 48 hr) of polyquaternium-16 (PQ-16) in a roll-on deodorant compared to active aluminium chlorohydrate. The new formula launched in 2016 presents a skin-friendly alternative in the range of deodorant on the mass market.[xx]

In terms of clean, sustainable, low-preservative formulas, ingredient manufacturers are stepping up. Symrise have re-investigated their biodegradable deodorant active SymDeo® B125, effectively preventing malodours. The company now claim the ingredient is ‘microbiome-friendly’, without disruption of natural axillary microbiome in contrast to the conventional antimicrobial Triclosan. First in carrying out research into deodorant actives impacting the human axillary microbiome, Symrise lead in the field of modern Micro Protection.[xxi] Schülke’s sensiva SC 50 (INCI: Ethylhexylglycerin) is a multifunctional active ingredient and antimicrobial, a medium-spreading hydrating emollient providing preservative-boosting efficacy in finished formulations. In vitro studies showed selective activity on odour-causing Gram-positive bacteria with a minimal effect on the microbiome compared with Triclosan that removes the majority of microorganisms.

We asked Edward Rolls, Global Account Director, Cosmetic Ingredients Division, Symrise AG to comment on the varying trends of deodorant technologies,

“For Deodorants, we find trends vary for different regions of the world. However, certainly for mainstream, performance will always remain key for the consumer. In addition to this, we expect trends around sustainability, using green chemistry ensuring deodorant ingredients are eco-friendly. As we learn more about the skin microbiome, ingredients will be more selective against the malodour producing bacteria in order to preserve the skin microbiome”.

Indie brands on the market

Indie brands have entered the niche and premium market with prebiotic/probiotic products and marketing-driven campaigns for environment aware and naturals driven consumers. An award-winning formula of Botanical Cream Deodorant by Aurelia Probiotic Skincare claims to be an ‘effective way of keeping bacteria and odours at bay’. In an innovative format of powdery cream, easy to apply and gentle on the skin, antimicrobial Arrowroot and Kaolin Clay work to absorb excess sweat, Bergamot and Lavender add fresh scent and Shea Butter moisturises to reduce rubbing.[xxii] Claiming up to 24 hours of protection against malodour and feeling fresh all day, the Bulldog Lemon & Bergamot Natural Deodorant uses Chicory Root prebiotic and Bergamot, Orange and Lemon scent.[xxiii] Xylitol used in Tom’s of Maine Prebiotic Natural Deodorant claims to ‘help keep skin in healthy balance by promoting the growth of good bacteria and ensure 48-hour odour protection [xxiv]. Quinoa & Prebiotics Deodorant by Green People claims to deliver 24 hours protection ‘being tough on odour but gentle on sensitive skin’ with prebiotics and zinc ricinoleate that absorbs odour. A long way to go in terms of rigorous scientific substantiation, the indie brands can command up to 20 times higher price for their products than a mass market brand. [xxv][xxvi]

We asked Dr Marie Drago, founder of Gallinée to share her thoughts on their approach to deodorant R&D and future of innovation,

“We would be very interested in developing microbiome-friendly deodorants, as it makes so much sense for a brand like us. For the moment, we are finding it difficult to combine the level of innovation that we want, with the retail prices for these kinds of products. As the company grow, so will our MOQ (minimum order quantity) so it should be easier soon. This disconnect between having a truly innovative product and the size of your company is true for every beauty category, but especially in the hygiene category. It’s especially a shame as there is so much to do with deodorants and the microbiome! Dr Chris Callawaert has been showing for years the damage usual deodorants can have on your armpit microbiome, so I think it’s time for a change. The next few years should be very interesting, especially as we will see novel actives that try to support the good armpit microbiome, instead of destroying every bacterium on the site”.

The future of deodorant technologies

Our understanding of microbiological and biochemical origin of human axillary odour asks for more research, starting with the microbiology and biochemistry of malodour formation on axillary skin, focussing on precursor-product relationships, odour-forming enzymes and metabolic pathways and causal organisms. There is no research published on existence of biofilms in the axilla, although presence of clusters has been implied in some studies.

We asked Professor Andrew McBain from University of Manchester to comment on the future of deodorant technologies,

“Improved knowledge of the organisms responsible for malodour, how they interact, and the metabolic processes involved, brings the opportunity to develop improved products. Whilst such knowledge can be generated through omic-based methods, there is still a place for microbial cultivation, in vitro modelling and conventional biochemical analysis.”

The NBIC community includes some of the best academic expertise in the area of axillary microbiome in the UK. If you are an SME, developing a new deodorant or an ingredient manufacturer working in deodorising technologies, we can support you in finding the right collaborator(s). Please don’t hesitate to get us touch with us at nbic@biofilms.ac.uk

[i] The physiology of the human axillary apocrine sweat gland

[ii] Dravnieks A., Krotoszynski B.K., Lieb W.E., Jungermann E. Influence of an antibacterial soap on various effluents from axillae. J. Soc. Cosmet. Chem. 1968;19:611–626.

[iv] Sudden change in body odor symptoms

[v] Questions About Deodorants

[vi] Why does my exercise clothing smell?

[vii] Characterization of Staphylococcus and Corynebacterium clusters in the human axillary region

[viii] Microbiological and biochemical origins of human axillary odour

[ix] Quantitative and qualitative composition of axilla microbiota in practically healthy individuals

[x] Mapping axillary microbiota responsible for body odours using a culture-independent approach

[xi] Biological and Chemical Processes that Lead to Textile Malodour Development

[xii] The effect of habitual and experimental antiperspirant and deodorant product use on the armpit microbiome

[xiii] Body Odor Research Opens Door for Next-gen Deodorants

[xiv] Structural basis of malodour precursor transport in the human axilla

[xv] Unilever and University of York Scientists Sniff Out B.O. Enzyme