By Shyam Gupta, PhD, BIODERM RESEARCH09.01.17
Plant-based essential oils are widely used in perfumery, food and flavor components, preservatives, household and laundry deodorizing, and medicinal treatments such as aromatherapy, topical pain relief, arthritis, and acne. An essential oil is a liquid containing volatile aroma compounds obtained from plants. It is “essential” as it contains the “essence of” the plant’s olfactory attributes. This property renders them “essential” in the composition of many fragrance additives used in cosmetics formulations, aromatherapy, massage oils, and medicinal agents.
Essential oils can penetrate skin and enhance topical delivery of active agents from topical formulations via a variety of mechanisms, which include disintegration of intercellular lipid structure in stratum corneum, interaction with intercellular proteins, and increasing the distribution of an active agent through the cellular membrane barrier. After skin penetration, essential oils are rapidly metabolized and excreted, suggesting their use as safe skin permeation enhancers.1 However, an unintended enhancement of an active agent into skin can also cause active agent efficacy and safety concerns.
Meditation, massage, and medicine can all be practiced via aromatherapy. The benefits of aromatherapy are well documented, ranging from the treatment of mild sleep disturbances, as an adjuvant treatment in cancer care, and massage therapy.2-4 The therapeutic utilization of essential oils, coupled with their skin penetration and inhalation exposure, can pose both enhanced benefits or significant toxicological concern, especially in terms of skin sensitization, irritation, allergic reactions, and contact dermatitis.5 Relative to allergic reactions, a large number of essential oils are used in cosmetics as aroma ingredients. In a literature study of 517 cosmetics formulations, 11 substances recognized as allergens were found in the essential oils used as fragrance components.6
An indiscriminate use of an essential oil or an aroma ingredient in a cosmetics formulation without the knowledge of the toxicology of their chemical constituents or biological effects is cause for concern. The knowledge of such information for cosmetics formulators, estheticians, and healthcare personnel can be highly beneficial for the consumer.7 This article shall present natural essential oils that are beneficial for skin and their application in topical body care applications and preservation of cosmetics formulations.
Massage Therapy for Holistic Well-Being
Essential oils for massage therapy and topical pain management are well-documented from antiquity: myrrh being the legendary example. In recent years, massage therapy has emerged as one of the most important complementary and alternative therapies for the management of a variety of ailments.
The spectrum of benefits provided by aroma-based massage therapy include arthritis, headache, back pain, and pain from cervical nerves (cervical radiculopathy).8-11Aromatherapy massage improves cancer patients’ well-being.12 Hand massage with aroma oils is reportedly beneficial for menstrual pain relief.13 Aroma massage has proven beneficial for sleep quality among women with hypertension.14
Aromatherapy Massage for Pain Relief
Massage therapy is an art and a science. The safe, non-pharmacological method of aromatherapy massage can be readily integrated into clinical practice. Well-known essential oils, such as rosemary, geranium, lavender, eucalyptus, and chamomile have been safely used. However, training and experience of aromatherapy and knowledge of the properties of essential oils used by massage personnel is critical to achieving optimal results.15
Massage and reflexology are simple and effective treatments that can be used to help manage pain and fatigue in patients with rheumatoid arthritis.16 A combination of aromatherapy massage and inhalation aromatherapy has been clinically proven to reduce burn patients’ anxiety and pain.17
In a clinical trial, 90 patients with osteoarthritis of the knee were studied in three groups: 1) treatment: massage with lavender oil; 2) placebo: massage with almond oil; and 3) control: without massage. Aromatherapy massage with lavender essential oil was found most effective in relieving pain in these patients.18
In another clinical trial, comparing the effectiveness of aromatherapy and acupressure massage therapies on the sleep quality of women, all experimental groups (blended essential oil, lavender oil, and acupressure massage) showed significant improvements in sleep quality. However, a significantly greater improvement in sleep quality was observed in the blended essential oil groups compared with the lavender oil group. This suggests use of a blend of essential oils to be better than a single entity.19
In a study to determine the effect of aromatherapy massage on quality of sleep and physiological parameters in intensive care patients, aromatherapy massage enhanced the sleep quality of patients and resulted in positive changes to their physiological parameters.20
Abdominal massage with essential oils has been found to be an effective complementary method to relieve menstrual pain (dysmenorrhea).21
The experience and knowledge of the massage therapist and selection of the right composition of massage oil are critical in the success of this ancient treatment method for providing relief and relaxation to the consumer.
Dermatological Safety of Massage Oils
Skin occupies a rather large surface area (~1.5 to 2.0 square meters). Exposure to any treatment with the massage oil can cause consumers perceived discomfort from erythema, irritation, and dermatitis.
Blended fragrances and natural essential oils have been used in perfumery and cosmetics. While many essential oils are now known to cause skin sensitization and dermatitis, the testing of fragrance oils that may contain such essential oils, for example Santalum album, Cananga odorata, Jasminum species, Mentha piperita, Melaleuca alternifolia, tea tree oil, and Lavandula angustifolia, may not reveal this potential safety concern (unless such essential oils are tested themselves).22
Even certain essential oils approved by the FDA as OTC external analgesics (for example, camphor, menthol, methyl salicylate, and turpentine oil), are classified as counter-irritants by the FDA monograph on External Analgesics Drug Products for Over the Counter Human Use. A number of essential oils, used as fragrances, are labeled by their INCI names on cosmetic products, which could be confusing to consumers in terms of ascertaining their dermal safety.23 To illustrate this further, contact dermatitis has been reported with a number of commonly used massage essential oils, including turmeric, eucalyptus and tea tree oils, lavender oil, citral (lemon oil), ylang ylang, sandalwood, and jasmine absolute.24-29 INCI names of these oils on a product label are not reflective of their common identity, hence not readily recognized by consumers.
Among 80 essential oils tested, oils from laurel, turpentine, orange, tea tree, citronella, ylang-ylang, sandalwood, clove, and costus root have all shown strong contact allergy.30 Additionally, co-reactivity with other essential oils, fragrance compositions, and other formulation components (which could enhance their skin penetration) is rather common.31 Since many of these essential oils may contain 50-200 individual chemical entities it is not always possible to pinpoint cause for such allergic responses.
In view of the aforementioned concerns, patch testing of individual components of essential oil blends and fragrances to ascertain their skin safety needs serious consideration before a product launch.31 A product recall or regulatory action based on consumer complaints is not a pleasant business matter.
Natural Oils for Massage Therapy
Massage with seed oils to alleviate pain has been practiced since ancient times. The clinical data on the efficacy of such treatments is recently of scientific interest. A clinical study found massage with topical sesame oil on limb trauma patients significantly reduced pain severity.32
In another clinical trial, infants were treated with olive oil massage for 10 days (three times for 15 minutes a day) and control group infants were massaged without olive oil. The neonatal weight gain in the infants with the oil massage was 21 grams daily in average, whereas the increase in infant massage without oil was 7 grams. The positive effect of infant massage with olive oil on weight gain in premature infants was recommended.33 However, in another study the use of topical oils on baby skin was shown to contribute to development of childhood atopic eczema.34
Natural oils are used throughout the world for general skin and hair care. However, there lacks scientific evidence to support this practice. In a recent study the effect of olive and sunflower seed oils on stratum corneum integrity and cohesion was studied. Topical application of olive oil for four weeks significantly reduced stratum corneum integrity and induced mild erythema. Sunflower seed oil preserved stratum corneum integrity with no erythema, and improved hydration. In contrast to sunflower seed oil, topical treatment with olive oil significantly damages the skin barrier, and therefore has the potential to promote atopic dermatitis.35
In another clinical trial comparing sunflower oil to an emollient on barrier development in healthy term newborns, both skin care regimes did not harm skin barrier function. The fatty acid content of seed oils seems to be a controlling factor for barrier function disorders (oleic acid being most disruptive).36
Coconut oil massage has been reported to reduce transepidermal water loss in neonates without effect on topical skin microbes.37In a comparative study, coconut oil was found superior to olive oil in skin moisturization and antibacterial protection.38 Similarly, coconut oil was found superior to mineral oil in treating atopic dermatitis in a study of 117 patients.39
The intercellular lipids of stratum corneum help maintain the skin barrier function. In a study to evaluate the effect of topically applied paraffin, petrolatum, almond oil, and jojoba oil on the intracellular lipid profile of stratum corneum, the plant-derived oils significantly changed the intracellular lipids.36,40 Squalane, now available from plant-based technology, could be an alternative for petroleum-based oils (mineral oil, paraffin) for massage applications.
It is worth noting that the (saturated) fats and oils that are not good nutritionally are better suited for topical applications. Conversely, the (unsaturated) fats and oils that are better suited for nutritional purposes are not suitable for skin care applications.41 This divergence could be of significance in the selection of oil/fat in emulsion-based skin care lotion and cream formulations.
Formulation Strategy for Massage Oils
The formulation of safe and functional massage oils should focus on the following minimal attributes:
• Pleasant aroma,
• Skin safety,
• Perceived consumer benefit,
• Ease of application, and
• Cost viability.
For this reason, the use of pure essential oils or certain seed oils must be avoided. The inclusion of a small quantity of an essential oil (for sensory benefits and formula esthetics) blended with a (mostly saturated) seed oil or hydrocarbon oil is prudent. This strategy can even reduce the amount of preservative for such formulations.38,42
Essential Oils as Preservatives
Many essential oils possess excellent antimicrobial and antifungal activity. Coupled with their insensitivity to varying pH ranges, their application as preservatives for cosmetics, foods and pharmaceuticals is receiving increasing attention. Consumer sensitivity due to reported allergic contact dermatitis of synthetics, and the development of resistant bacteria in cosmetics preserved with synthetic antibacterial agents is further driving this trend toward natural preservatives.43-44
It is worth noting that the use of synthetic preservatives at their recommended dose levels did not seem to cause any skin irritation in an analysis of 45,000 human subjects.45 While a large number of essential oils are known to possess antibacterial and antifungal activity, their safety, efficacy, and stability in formulated cosmetics as preservatives has been of limited scope. A number of such preservatives contain phenolic or polyunsaturated antimicrobial and antioxidant components, which renders them sensitive to discoloration due to air oxidation (especially in formulations above pH 8.0 and/or presence of oxidizing metals such as copper, iron, and nickel.
A few recent examples of essential oil-based preservatives in formulated products are noted below in anticipation of further commercial development of essential oils as cosmetics preservatives. In this regard, the olfactory and color attributes of certain essential oils continue to pose formulating challenges as preservatives. The essential oil of curcumin (Curcuma longa), for example, has shown potent antibacterial and antifungal activity.46 The yellow color and strong medicinal odor of turmeric oil prevents its use as a natural preservative in cosmetics. Ginger oil has been reported as a good preservative for fish products.47 Strong spicy aroma of this oil, however, does not offer promise for its use as a cosmetic preservative.
Salva-de-marajó: Plants of Lippia sp. (origanum family) are well known for their aromatic constituents. Lippia origanoides is a very aromatic shrub distributed from North America to South America, with prominent occurrence in the Amazonian region of Brazil, the Guianas, Venezuela, and Colombia.48
A recent study on the essential oil of L. origanoides, which consisted mainly of oxygenated monoterpenes (38%) and carvacrol (26%), showed that it inhibited the growth of all the tested microorganisms. The Ames test indicated that this oil was non-mutagenic. In combination with polysorbate 80, the essential oil exerted preservative action on orange juice, as well as cosmetic and pharmaceutical compositions, especially in the case of aqueous-based formulations.49
West Indian Raspberry (Rubus rosifolius): This plant is a prickly shrub native to rainforests and forests of the Himalayas, East Asia, and eastern Australia. The extract of this plant was evaluated as a preservative at 0.2% (w/w) use level in two different base formulations (emulsion and gel). The microbial challenge test was performed with the standardized microorganisms. The results demonstrated the extract reduced the bacterial inoculate. However, it was not an effective preservative against fungi, thus requiring a complementary antifungal agent.50
Self-Preserving Cosmetics. An emerging trend of self-preserving and preservative-free cosmetics is on the horizon. This feat is achieved by using a combination of antioxidants, chelating agents, and bioactive essential oils.51 Phenethyl alcohol, an essential oil component of rose oil, in combination with caprylyl glycol and glyceryl caprylate, is a new preservative for emulsion formulations, especially those of droplet particle size in the range of 100-900 nm.52 A design space model for preservative optimization, developed for synthetic preservatives, may be applicable for natural ingredients-based cosmetic preservatives.53
The future of self-preserving and preservatives-free formulations is of limited practicality due to a plethora of reasons, including limited availability of natural preservatives with proven broad-spectrum efficacy at low (0.1-0.5%) use levels, the complexity of additives and ingredients in a formula, pH ranges, stability criteria, activity against mutations of resistant bacteria, and regulatory requirements of such formulations.
Summary
The formulation of essential oil-based massage oils requires a prudent selection of essential oils and other emollient ingredients for their consumer acceptance, skin safety, and sensorial attributes. The application of essential oils for preservation of cosmetics replacing synthetics is still in its developmental stages.
The use of seed oils for massage requires a careful selection of such oils. Oleic acid, among all other fatty acid constituents of seed oils, has been shown to penetrate skin the most.54 This may explain why olive oil causes dermatitis on topical application. The oils that are high in oleic content (C18-1) need discretion for massage applications.
The technologies for preservative-free cosmetics are envisioned to be of limited applicability due to the variety of ingredients used in such formulations. The mutations of bacteria resistant to synthetic and other preservatives in cosmetics formulations shall pose additional challenges for preservatives-free cosmetics research.
About the author: Shyam Gupta is an international consultant in innovative topical and skin care formulations based on new ingredients and delivery systems with over 100 patents, patent applications, cosmetics publications, and book chapters. He specializes in consumer-desirable, nature-based ingredients with incomparable efficacy and performance attributes. For more information: 602-996-9700, e-mail: shyam@biodermresearch.com, website: www.biodermresearch.com
References
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3. Boehm et al., Aromatherapy as an adjuvant treatment in cancer care--a descriptive systematic review, Afr J Tradit Complement Altern Med. 2012 Jul 1;9(4):503-18. eCollection 2012.
4. Shin et al., Massage with or without aromatherapy for symptom relief in people with cancer, Cochrane Database Syst Rev. 2016 Jun 3;(6):CD009873.
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11. Wei et al., Clinical Evidence of Chinese Massage Therapy (Tui Na) for Cervical Radiculopathy: A Systematic Review and Meta-Analysis, Evid Based Complement Alternat Med. 2017; 2017:9519285. Epub 2017 Feb 20.
12. Kwong et al., Experiences of aromatherapy massage among adult female cancer patients: A qualitative study, J Clin Nurs. 2017 Mar 2. [Epub ahead of print]; Chang, Effects of aroma hand massage on pain, state anxiety and depression in hospice patients with terminal cancer, Taehan Kanho Hakhoe Chi. 2008 Aug;38(4):493-502.
13. Marzouk et al., The effect of aromatherapy abdominal massage on alleviating menstrual pain in nursing students: a prospective randomized cross-over study, Evid Based Complement Alternat Med. 2013; 2013:742421. Epub 2013 Apr 11.
14. Ju et al., Effects of aroma massage on home blood pressure, ambulatory blood pressure, and sleep quality in middle-aged women with hypertension, Evid Based Complement Alternat Med. 2013; 2013:403251. Epub 2013 Jan 30.
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16. Gok Metin et al., The Effects of Aromatherapy Massage and Reflexology on Pain and Fatigue in Patients with Rheumatoid Arthritis: A Randomized Controlled Trial, Pain Manag Nurs. 2016 Apr;17(2):140-9. Epub 2016 Apr 16.
17. Seyyed-Rasooli et al., Comparing the effects of aromatherapy massage and inhalation aromatherapy on anxiety and pain in burn patients: A single-blind randomized clinical trial, Burns. 2016 Dec;42(8):1774-1780. Epub 2016 Aug 27.
18. Nasiri et al., Effect of aromatherapy massage with lavender essential oil on pain in patients with osteoarthritis of the knee: A randomized controlled clinical trial, Complement Ther Clin Pract. 2016 Nov;25:75-80. Epub 2016 Aug 3.
19. Kao et al., Comparisons for Effectiveness of Aromatherapy and Acupressure Massage on Quality of Life in Career Women: A Randomized Controlled Trial, J Altern Complement Med. 2017 Jun;23(6):451-460. Epub 2017 May 15; Hongratanaworakit, Aroma-therapeutic effects of massage blended essential oils on humans, Nat Prod Commun. 2011 Aug;6(8):1199-204.
20. Ozlu et al., Effects of Aromatherapy Massage on the Sleep Quality and Physiological Parameters of Patients in a Surgical Intensive Care Unit, Afr J Tradit Complement Altern Med. 2017 Mar 1;14(3):83-88. eCollection 2017.
21. Sut et al., Effect of aromatherapy massage on pain in primary dysmenorrhea: A meta-analysis, Complement Ther Clin Pract. 2017 May;27:5-10. Epub 2017 Jan 18.
22. Warshaw et al., Positive Patch-Test Reactions to Essential Oils in Consecutive Patients: Results From North America and Central Europe, Dermatitis. 2017 Jun 13. [Epub ahead of print].
23. Sabroe et al., Contact allergy to essential oils cannot always be predicted from allergy to fragrance markers in the baseline series, Contact Dermatitis. 2016 Apr;74(4):236-41. Epub 2016 Jan 25.
24. Lopes-Villafuerte et al., Contact dermatitis caused by turmeric in a massage oil, Contact Dermatitis. 2016 Jul;75(1):52-3.
25. Higgins et al., Eucalyptus oil: contact allergy and safety, Contact Dermatitis. 2015 May;72(5):344-6. Epub 2015 Mar 6; de Groot et al., Eucalyptus oil and tea tree oil, Contact Dermatitis. 2015 Dec;73(6):381-6. Epub 2015 Jul 15; Ahlin et al., High frequency of contact allergy caused by alternative medicine substances. Tea tree oil tops the list, Lakartidningen. 2011 Aug 10-23;108(32-33):1487-90.
26. Varma et al., Combined contact allergy to tea tree oil and lavender oil complicating chronic vulvovaginitis, Contact Dermatitis. 2000 May;42(5):309-10.
27. De Mozzi et al., An outbreak of allergic contact dermatitis caused by citral in beauticians working in a health spa, Contact Dermatitis. 2014 Jun;70(6):377-9.
28. Romaguera et al., Occupational contact dermatitis from ylang-ylang oil, Contact Dermatitis. 2000 Oct;43(4):251.
29. Vejanurug et al., Fragrance allergy could be missed without patch testing with 26 individual fragrance allergens, Contact Dermatitis. 2016 Apr;74(4):230-5. Epub 2016 Jan 19; Cheng et al., Fragrance allergic contact dermatitis, Dermatitis. 2014 Sep-Oct;25(5):232-45.
30. de Groot et al., Essential Oils, Part IV: Contact Allergy, Dermatitis. 2016 Jul-Aug;27(4):170-5; de Groot et al., Essential Oils, Part III: Chemical Composition, Dermatitis. 2016 Jul-Aug;27(4):161-9.
31. de Groot et al., Essential Oils, Part VI: Sandalwood Oil, Ylang-Ylang Oil, and Jasmine Absolute, Dermatitis. 2017 Jan/Feb;28(1):14-21.
32. Nasiri et al., Effect of light pressure stroking massage with sesame (Sesamum indicum L.) oil on alleviating acute traumatic limbs pain: A triple-blind controlled trial in emergency department, Complement Ther Med. 2017 Jun;32:41-48. Epub 2017 Mar 16; Bigdeli Shamloo et al., The Effects of Topical Sesame (Sesamum indicum) Oil on Pain Severity and Amount of Received Non-Steroid Anti-Inflammatory Drugs in Patients With Upper or Lower Extremities, Trauma,Anesth Pain Med. 2015 Jun 22;5(3):e25085. eCollection 2015 Jun.
33. Jabraeile et al., Effect of olive oil massage on weight gain in preterm infants: A randomized controlled clinical trial, Niger Med J. 2016 May-Jun;57(3):160-3.
34. Cooke et al., Olive Oil, Sunflower Oil Or No Oil for Baby Dry Skin or Massage: A Pilot, Assessor-blinded, Randomized Controlled Trial (the Oil in Baby SkincaRE [OBSeRvE] Study), Acta Derm Venereol. 2016 Mar;96(3):323-30.
35. Danby et al., Effect of olive and sunflower seed oil on the adult skin barrier: implications for neonatal skin care, Pediatr Dermatol. 2013 Jan-Feb;30(1):42-50. Epub 2012 Sep 20.
36. Kanti et al., Influence of sunflower seed oil or baby lotion on the skin barrier function of newborns: A pilot study, J Cosmet Dermatol. 2017 Jan 10. [Epub ahead of print]; Kezutyte et al., Studying the penetration of fatty acids into human skin by ex vivo TOF-SIMS imaging, Biointerphases (2013) 8: 3.
37. Nangia et al., Topical Oil Application and Trans-Epidermal Water Loss in Preterm Very Low Birth Weight Infants-A Randomized Trial, J Trop Pediatr. 2015 Dec;61(6):414-20. Epub 2015 Sep 3.
38. Verallo-Rowell et al., Novel antibacterial and emollient effects of coconut and virgin olive oils in adult atopic dermatitis, Dermatitis. 2008 Nov-Dec;19(6):308-15.
39. Evangelista et al., The effect of topical virgin coconut oil on SCORAD index, transepidermal water loss, and skin capacitance in mild to moderate pediatric atopic dermatitis: a randomized, double-blind, clinical trial, Int J Dermatol. 2014 Jan;53(1):100-8. Epub 2013 Dec 10.
40. Choe at al., In vivo confocal Raman microscopic determination of depth profiles of the stratum corneum lipid organization influenced by application of various oils, J Dermatol Sci. 2017 May 6. pii: S0923-1811(17)30133-0. [Epub ahead of print]; van Smeden et al., The importance of free fatty acid chain length for the skin barrier function in atopic eczema patients, Exp Dermatol. 2014 Jan;23(1):45-52.
41. Osman et al., Synergistic analgesic, anti-pyretic and anti-inflammatory effects of extra virgin olive oil and ibuprofen in different experimental models in albino mice, Int J Rheum Dis. 2017 Jun 7. [Epub ahead of print]; Elias et al., Lipotoxicity in Obesity: Benefit of Olive Oil, Adv Exp Med Biol. 2017;960:607-617; Lama et al., Polyphenol-rich virgin olive oil reduces insulin resistance and liver inflammation and improves mitochondrial dysfunction in high-fat diet fed rats, Mol Nutr Food Res. 2017 Mar;61(3). Epub 2016 Dec 20.
42. Verallo-Rowell et al., Natural (Mineral, Vegetable, Coconut, Essential) Oils and Contact Dermatitis, Curr Allergy Asthma Rep. 2016 Jul;16(7):51.
43. Deza et al., Allergic contact dermatitis in preservatives: current standing and future options, Curr Opin Allergy Clin Immunol. 2017 May 25. [Epub ahead of print]; Yim et al., Contact dermatitis caused by preservatives, Dermatitis. 2014 Sep-Oct;25(5):215-31; Nabavi et al., Antibacterial Effects of Cinnamon: From Farm to Food, Cosmetic and Pharmaceutical Industries, Nutrients. 2015 Sep 11;7(9):7729-48.
44. Orus et al, Increasing antibiotic resistance in preservative-tolerant bacterial strains isolated from cosmetic products, Int Microbiol. 2015 Mar;18(1):51-9; Periame et al., Phenotypic changes contributing to Enterobacter gergoviae biocide resistance, Lett Appl Microbiol. 2015 Aug;61(2):121-9. Epub 2015 May 29; Periame et al., Enterobacter gergoviae membrane modifications are involved in the adaptive response to preservatives used in cosmetic industry, J Appl Microbiol. 2015 Jan;118(1):49-61. Epub 2014 Nov 25.
45. Walters et al., Human Cumulative Irritation Tests of Common Preservatives Used in Personal Care Products: A Retrospective Analysis of Over 45 000 Subjects, Toxicol Sci. 2015 Nov;148(1):101-7. Epub 2015 Jul 23.
46. Hu et al., Mechanisms of antifungal and anti-aflatoxigenic properties of essential oil derived from turmeric (Curcuma longa L.) on Aspergillus flavus, Food Chem. 2017 Apr 1;220:1-8. Epub 2016 Sep 29; Lee et al., Essential oil of Curcuma longa inhibits Streptococcus mutans biofilm formation, J Food Sci. 2011 Nov-Dec;76(9):H226-30; Dias Ferreira et al., The inhibitory effects of Curcuma longa L. essential oil and curcumin on Aspergillus flavus link growth and morphology, ScientificWorldJournal. 2013 Dec 3;2013:343804. eCollection 2013.
47. Verma et al., Chemical composition and antibacterial, antifungal, allelopathic and acetylcholinesterase inhibitory activities of cassumunar-ginger, J Sci Food Agric. 2017 Jun 6. [Epub ahead of print]; Snuossi et al., Laurus nobilis, Zingiber officinale and Anethum graveolens Essential Oils: Composition, Antioxidant and Antibacterial Activities against Bacteria Isolated from Fish and Shellfish, Molecules. 2016 Oct 22;21(10). pii: E1414.
48. Oliviera et al., Ethnopharmacological studies of Lippia origanoides,Revista Brasileira de Farmacognosia,Rev. bras. farmacogn. vol.24 no.2 Curitiba Mar./Apr. 2014.
49. Hernandes et al., Lippia origanoides essential oil: an efficient and safe alternative to preserve food, cosmetic and pharmaceutical products, J Appl Microbiol. 2017 Apr;122(4):900-910. Epub 2017 Feb 15.
50. Ostrosky et al., Rubus rosaefolius extract as a natural preservative candidate in topical formulations, AAPS PharmSciTech. 2011 Jun;12(2):732-7. Epub 2011 Jun 4.
51. Varvaresou et al., Self-preserving cosmetics, Int J Cosmet Sci. 2009 Jun;31(3):163-75. Epub 2009 Mar 19; Papageorgiou et al., New alternatives to cosmetics preservation, J Cosmet Sci. 2010 Mar-Apr;61(2):107-23.
52. Fang et al., A new alternative to cosmetics preservation and the effect of the particle size of the emulsion droplets on preservation efficacy, Int J Cosmet Sci. 2016 Oct;38(5):496-503. Epub 2016 Apr 5.
53. Lourenço et al., Design Space Approach for Preservative System Optimization of an Anti-Aging Eye Fluid Emulsion, J Pharm Pharm Sci. 2015;18(3):551-61.
54. Čižinauskas et al., Fatty acids penetration into human skin ex vivo: A TOF-SIMS analysis approach, Biointerphases. 2017 Mar 2;12(1):011003; Kumar et al., Fatty acid vesicles acting as expanding horizon for transdermal delivery, Artif Cells Nanomed Biotechnol. 2017 Mar;45(2):251-260. Epub 2016 Feb 18.
Essential oils can penetrate skin and enhance topical delivery of active agents from topical formulations via a variety of mechanisms, which include disintegration of intercellular lipid structure in stratum corneum, interaction with intercellular proteins, and increasing the distribution of an active agent through the cellular membrane barrier. After skin penetration, essential oils are rapidly metabolized and excreted, suggesting their use as safe skin permeation enhancers.1 However, an unintended enhancement of an active agent into skin can also cause active agent efficacy and safety concerns.
Meditation, massage, and medicine can all be practiced via aromatherapy. The benefits of aromatherapy are well documented, ranging from the treatment of mild sleep disturbances, as an adjuvant treatment in cancer care, and massage therapy.2-4 The therapeutic utilization of essential oils, coupled with their skin penetration and inhalation exposure, can pose both enhanced benefits or significant toxicological concern, especially in terms of skin sensitization, irritation, allergic reactions, and contact dermatitis.5 Relative to allergic reactions, a large number of essential oils are used in cosmetics as aroma ingredients. In a literature study of 517 cosmetics formulations, 11 substances recognized as allergens were found in the essential oils used as fragrance components.6
An indiscriminate use of an essential oil or an aroma ingredient in a cosmetics formulation without the knowledge of the toxicology of their chemical constituents or biological effects is cause for concern. The knowledge of such information for cosmetics formulators, estheticians, and healthcare personnel can be highly beneficial for the consumer.7 This article shall present natural essential oils that are beneficial for skin and their application in topical body care applications and preservation of cosmetics formulations.
Massage Therapy for Holistic Well-Being
Essential oils for massage therapy and topical pain management are well-documented from antiquity: myrrh being the legendary example. In recent years, massage therapy has emerged as one of the most important complementary and alternative therapies for the management of a variety of ailments.
The spectrum of benefits provided by aroma-based massage therapy include arthritis, headache, back pain, and pain from cervical nerves (cervical radiculopathy).8-11Aromatherapy massage improves cancer patients’ well-being.12 Hand massage with aroma oils is reportedly beneficial for menstrual pain relief.13 Aroma massage has proven beneficial for sleep quality among women with hypertension.14
Aromatherapy Massage for Pain Relief
Massage therapy is an art and a science. The safe, non-pharmacological method of aromatherapy massage can be readily integrated into clinical practice. Well-known essential oils, such as rosemary, geranium, lavender, eucalyptus, and chamomile have been safely used. However, training and experience of aromatherapy and knowledge of the properties of essential oils used by massage personnel is critical to achieving optimal results.15
Massage and reflexology are simple and effective treatments that can be used to help manage pain and fatigue in patients with rheumatoid arthritis.16 A combination of aromatherapy massage and inhalation aromatherapy has been clinically proven to reduce burn patients’ anxiety and pain.17
In a clinical trial, 90 patients with osteoarthritis of the knee were studied in three groups: 1) treatment: massage with lavender oil; 2) placebo: massage with almond oil; and 3) control: without massage. Aromatherapy massage with lavender essential oil was found most effective in relieving pain in these patients.18
In another clinical trial, comparing the effectiveness of aromatherapy and acupressure massage therapies on the sleep quality of women, all experimental groups (blended essential oil, lavender oil, and acupressure massage) showed significant improvements in sleep quality. However, a significantly greater improvement in sleep quality was observed in the blended essential oil groups compared with the lavender oil group. This suggests use of a blend of essential oils to be better than a single entity.19
In a study to determine the effect of aromatherapy massage on quality of sleep and physiological parameters in intensive care patients, aromatherapy massage enhanced the sleep quality of patients and resulted in positive changes to their physiological parameters.20
Abdominal massage with essential oils has been found to be an effective complementary method to relieve menstrual pain (dysmenorrhea).21
The experience and knowledge of the massage therapist and selection of the right composition of massage oil are critical in the success of this ancient treatment method for providing relief and relaxation to the consumer.
Dermatological Safety of Massage Oils
Skin occupies a rather large surface area (~1.5 to 2.0 square meters). Exposure to any treatment with the massage oil can cause consumers perceived discomfort from erythema, irritation, and dermatitis.
Blended fragrances and natural essential oils have been used in perfumery and cosmetics. While many essential oils are now known to cause skin sensitization and dermatitis, the testing of fragrance oils that may contain such essential oils, for example Santalum album, Cananga odorata, Jasminum species, Mentha piperita, Melaleuca alternifolia, tea tree oil, and Lavandula angustifolia, may not reveal this potential safety concern (unless such essential oils are tested themselves).22
Even certain essential oils approved by the FDA as OTC external analgesics (for example, camphor, menthol, methyl salicylate, and turpentine oil), are classified as counter-irritants by the FDA monograph on External Analgesics Drug Products for Over the Counter Human Use. A number of essential oils, used as fragrances, are labeled by their INCI names on cosmetic products, which could be confusing to consumers in terms of ascertaining their dermal safety.23 To illustrate this further, contact dermatitis has been reported with a number of commonly used massage essential oils, including turmeric, eucalyptus and tea tree oils, lavender oil, citral (lemon oil), ylang ylang, sandalwood, and jasmine absolute.24-29 INCI names of these oils on a product label are not reflective of their common identity, hence not readily recognized by consumers.
Among 80 essential oils tested, oils from laurel, turpentine, orange, tea tree, citronella, ylang-ylang, sandalwood, clove, and costus root have all shown strong contact allergy.30 Additionally, co-reactivity with other essential oils, fragrance compositions, and other formulation components (which could enhance their skin penetration) is rather common.31 Since many of these essential oils may contain 50-200 individual chemical entities it is not always possible to pinpoint cause for such allergic responses.
In view of the aforementioned concerns, patch testing of individual components of essential oil blends and fragrances to ascertain their skin safety needs serious consideration before a product launch.31 A product recall or regulatory action based on consumer complaints is not a pleasant business matter.
Natural Oils for Massage Therapy
Massage with seed oils to alleviate pain has been practiced since ancient times. The clinical data on the efficacy of such treatments is recently of scientific interest. A clinical study found massage with topical sesame oil on limb trauma patients significantly reduced pain severity.32
In another clinical trial, infants were treated with olive oil massage for 10 days (three times for 15 minutes a day) and control group infants were massaged without olive oil. The neonatal weight gain in the infants with the oil massage was 21 grams daily in average, whereas the increase in infant massage without oil was 7 grams. The positive effect of infant massage with olive oil on weight gain in premature infants was recommended.33 However, in another study the use of topical oils on baby skin was shown to contribute to development of childhood atopic eczema.34
Natural oils are used throughout the world for general skin and hair care. However, there lacks scientific evidence to support this practice. In a recent study the effect of olive and sunflower seed oils on stratum corneum integrity and cohesion was studied. Topical application of olive oil for four weeks significantly reduced stratum corneum integrity and induced mild erythema. Sunflower seed oil preserved stratum corneum integrity with no erythema, and improved hydration. In contrast to sunflower seed oil, topical treatment with olive oil significantly damages the skin barrier, and therefore has the potential to promote atopic dermatitis.35
In another clinical trial comparing sunflower oil to an emollient on barrier development in healthy term newborns, both skin care regimes did not harm skin barrier function. The fatty acid content of seed oils seems to be a controlling factor for barrier function disorders (oleic acid being most disruptive).36
Coconut oil massage has been reported to reduce transepidermal water loss in neonates without effect on topical skin microbes.37In a comparative study, coconut oil was found superior to olive oil in skin moisturization and antibacterial protection.38 Similarly, coconut oil was found superior to mineral oil in treating atopic dermatitis in a study of 117 patients.39
The intercellular lipids of stratum corneum help maintain the skin barrier function. In a study to evaluate the effect of topically applied paraffin, petrolatum, almond oil, and jojoba oil on the intracellular lipid profile of stratum corneum, the plant-derived oils significantly changed the intracellular lipids.36,40 Squalane, now available from plant-based technology, could be an alternative for petroleum-based oils (mineral oil, paraffin) for massage applications.
It is worth noting that the (saturated) fats and oils that are not good nutritionally are better suited for topical applications. Conversely, the (unsaturated) fats and oils that are better suited for nutritional purposes are not suitable for skin care applications.41 This divergence could be of significance in the selection of oil/fat in emulsion-based skin care lotion and cream formulations.
Formulation Strategy for Massage Oils
The formulation of safe and functional massage oils should focus on the following minimal attributes:
• Pleasant aroma,
• Skin safety,
• Perceived consumer benefit,
• Ease of application, and
• Cost viability.
For this reason, the use of pure essential oils or certain seed oils must be avoided. The inclusion of a small quantity of an essential oil (for sensory benefits and formula esthetics) blended with a (mostly saturated) seed oil or hydrocarbon oil is prudent. This strategy can even reduce the amount of preservative for such formulations.38,42
Essential Oils as Preservatives
Many essential oils possess excellent antimicrobial and antifungal activity. Coupled with their insensitivity to varying pH ranges, their application as preservatives for cosmetics, foods and pharmaceuticals is receiving increasing attention. Consumer sensitivity due to reported allergic contact dermatitis of synthetics, and the development of resistant bacteria in cosmetics preserved with synthetic antibacterial agents is further driving this trend toward natural preservatives.43-44
It is worth noting that the use of synthetic preservatives at their recommended dose levels did not seem to cause any skin irritation in an analysis of 45,000 human subjects.45 While a large number of essential oils are known to possess antibacterial and antifungal activity, their safety, efficacy, and stability in formulated cosmetics as preservatives has been of limited scope. A number of such preservatives contain phenolic or polyunsaturated antimicrobial and antioxidant components, which renders them sensitive to discoloration due to air oxidation (especially in formulations above pH 8.0 and/or presence of oxidizing metals such as copper, iron, and nickel.
A few recent examples of essential oil-based preservatives in formulated products are noted below in anticipation of further commercial development of essential oils as cosmetics preservatives. In this regard, the olfactory and color attributes of certain essential oils continue to pose formulating challenges as preservatives. The essential oil of curcumin (Curcuma longa), for example, has shown potent antibacterial and antifungal activity.46 The yellow color and strong medicinal odor of turmeric oil prevents its use as a natural preservative in cosmetics. Ginger oil has been reported as a good preservative for fish products.47 Strong spicy aroma of this oil, however, does not offer promise for its use as a cosmetic preservative.
Salva-de-marajó: Plants of Lippia sp. (origanum family) are well known for their aromatic constituents. Lippia origanoides is a very aromatic shrub distributed from North America to South America, with prominent occurrence in the Amazonian region of Brazil, the Guianas, Venezuela, and Colombia.48
A recent study on the essential oil of L. origanoides, which consisted mainly of oxygenated monoterpenes (38%) and carvacrol (26%), showed that it inhibited the growth of all the tested microorganisms. The Ames test indicated that this oil was non-mutagenic. In combination with polysorbate 80, the essential oil exerted preservative action on orange juice, as well as cosmetic and pharmaceutical compositions, especially in the case of aqueous-based formulations.49
West Indian Raspberry (Rubus rosifolius): This plant is a prickly shrub native to rainforests and forests of the Himalayas, East Asia, and eastern Australia. The extract of this plant was evaluated as a preservative at 0.2% (w/w) use level in two different base formulations (emulsion and gel). The microbial challenge test was performed with the standardized microorganisms. The results demonstrated the extract reduced the bacterial inoculate. However, it was not an effective preservative against fungi, thus requiring a complementary antifungal agent.50
Self-Preserving Cosmetics. An emerging trend of self-preserving and preservative-free cosmetics is on the horizon. This feat is achieved by using a combination of antioxidants, chelating agents, and bioactive essential oils.51 Phenethyl alcohol, an essential oil component of rose oil, in combination with caprylyl glycol and glyceryl caprylate, is a new preservative for emulsion formulations, especially those of droplet particle size in the range of 100-900 nm.52 A design space model for preservative optimization, developed for synthetic preservatives, may be applicable for natural ingredients-based cosmetic preservatives.53
The future of self-preserving and preservatives-free formulations is of limited practicality due to a plethora of reasons, including limited availability of natural preservatives with proven broad-spectrum efficacy at low (0.1-0.5%) use levels, the complexity of additives and ingredients in a formula, pH ranges, stability criteria, activity against mutations of resistant bacteria, and regulatory requirements of such formulations.
Summary
The formulation of essential oil-based massage oils requires a prudent selection of essential oils and other emollient ingredients for their consumer acceptance, skin safety, and sensorial attributes. The application of essential oils for preservation of cosmetics replacing synthetics is still in its developmental stages.
The use of seed oils for massage requires a careful selection of such oils. Oleic acid, among all other fatty acid constituents of seed oils, has been shown to penetrate skin the most.54 This may explain why olive oil causes dermatitis on topical application. The oils that are high in oleic content (C18-1) need discretion for massage applications.
The technologies for preservative-free cosmetics are envisioned to be of limited applicability due to the variety of ingredients used in such formulations. The mutations of bacteria resistant to synthetic and other preservatives in cosmetics formulations shall pose additional challenges for preservatives-free cosmetics research.
About the author: Shyam Gupta is an international consultant in innovative topical and skin care formulations based on new ingredients and delivery systems with over 100 patents, patent applications, cosmetics publications, and book chapters. He specializes in consumer-desirable, nature-based ingredients with incomparable efficacy and performance attributes. For more information: 602-996-9700, e-mail: shyam@biodermresearch.com, website: www.biodermresearch.com
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