HYPOALLERGENIC BOTANICAL COSMECEUTICALS DO NOT PRODUCE ALLERGIC REACTIONS

The term hypoallergenic is a marketing term meaning ‘reduced allergy’ not ‘nonallergenic’. This term was first popularized by Clinique cosmetics, a division of Estée Lauder, for advertising purposes to create a unique image for this new make-up line. There are no governmental guidelines that apply to the hypoallergenic concept. Dermatologists should consider hypoallergenic cosmetics as a source of allergic contact dermatitis for all patients Fig. 30.1. It is hoped that companies making the hypoallergenic claim have conducted repeat insult patch testing as part of their product safety assessment, but this cannot always be assumed.

Fig. 30.1 Allergic contact dermatitis to a hypoallergenic product

PRESERVATIVE-FREE BOTANICAL COSMECEUTICALS PRODUCE FEWER SKIN REACTIONS

Many products are now claiming to be better for the skin because they are ‘preservative-free’. This is a somewhat meaningless term, since all products must contain preservatives Fig. 30.2. Preservatives fall into several categories. There are preservatives that are classified as antioxidants. These are substances designed to prevent the rancidity of the oils in the formulation and prevent the breakdown of coloring agents. Common antioxidant preservatives that perform this function are tocopheryl acetate, retinyl palmitate and ascorbic acid. These are of the same family as the topical vitamin E, A, and C additives that many companies are claiming prevent skin oxidation. Oxidation is a universal event leading to aging of any living or biologically derived material. However, tocopheryl acetate, retinyl palmitate, and ascorbic acid in the concentrations used for product preservation do not have much biologic activity for the prevention of skin oxidation.

Fig. 30.2 All topical vitamin C preparations must contain a preservative to prevent oxidation of the ascorbic acid and darkening of the product

Another category of preservatives comprises those aimed at preventing microbe contamination, whether the source is a bacterium, yeast, or fungus. These are substances such as phenoxyethanol, Kathon-CG, Bronopol, parabens, etc. All formulations that contain water must contain some type of preservative to maintain purity on the shelf, whether it is called a preservative or not. Some clove extracts, such as eugenol, have preservative characteristics and ‘natural’ formulations may use ingredients for this purpose. Some traditional preservatives, such as phenoxyethanol, have a rose fragrance and may have their stated purpose as a fragrance, even though they are functioning as a preservative. Most companies use a preservative in anhydrous formulations, even though it may not be necessary.

In summary, there is no such thing as a ‘preservative-free’ formulation, unless it is pure petrolatum. Preservatives may have other functions or may be natural ingredients with preservative properties, but all products must be protected against contamination and oxidation.

BOTANICAL COSMECEUTICALS ARE NATURAL

There is a misconception that all botanical cosmeceuticals are natural because they are derived from plant sources. Most botanical actives were first discovered and isolated from plant sources, but are no longer obtained from plants. This is far too expensive in most cases. Many botanical extracts are modified and chemically synthesized to obtain a form that can be easily incorporated into a skin moisturizer. Ground-up leaves or cactus spines Fig. 30.3 typically do not create an aesthetic feel when sprinkled in a moisturizer and undergo extensive processing to create a liquid or fine powder suitable for cosmeceutical use. An excellent example is allantoin, botanically obtained from the root of the comfrey plant. However, most allantoin used as an anti-inflammatory agent in sensitive skin cosmeceuticals is obtained from uric acid. It is bioidentical to plant-derived allantoin, but synthesized in a chemical plant, not grown by ‘mother nature’. Thus, the claim that botanicals are natural is meaningless. All chemicals are in some sense natural, since they are derived from materials present on the earth.

Fig. 30.3 Cactus extract is usually a highly processed material, since cactus spines would not be acceptable for topical application

BOTANICALLY DERIVED FRAGRANCES DO NOT CAUSE ALLERGIC CONTACT DERMATITIS

Many of the newer botanically derived fragrances entering the market claim to be ‘hypoallergenic’. Remember that the term hypoallergenic means reduced allergic potential and not zero allergic potential. Also remember that hypoallergenic refers to a reduced incidence of allergic contact dermatitis and not a reduced incidence of vasomotor rhinitis or other untoward nasal or respiratory effects from the perfume. Botanically derived fragrances can most certainly cause allergic contact dermatitis in the sensitized patient. I usually have my patients apply the new hypoallergenic perfume in one antecubital fossa for five nights in a row prior to more liberal application to avoid widespread allergic contact dermatitis Fig. 30.4.

Fig. 30.4 Use testing in the antecubital fossa is an excellent method for evaluating possible ingredient allergy in sensitive skin patients

BOTANICAL COSMECEUTICALS CAN REDUCE SEBUM PRODUCTION

Many skin care products on the market today contain botanical ingredients that claim to decrease facial sebum. Sometimes it is unclear from the label whether the appearance of sebum is reduced or whether the production of sebum is decreased. One mechanism for reducing the appearance of facial oil is to adsorb the sebum into 1–30 μm diameter polymer spheres composed of three monomers: isobornyl methacrylate (IBMA), lauryl methacrylate (LMA), and divinylbenzene (DVB). The DVB serves to crosslink the IBMA and LMA to form a three-dimensional copolymer network capable of absorbing liquid oil-soluble substances. This technology was originally developed to control industrial organic solvent spills.

The sebum is absorbed by the polymer through imbibition, since the oil can be absorbed, but not released. This is due to the sebum being held inside the polymer with Van der Waals forces, creating a strong attraction without chemical bonding. Thus, the oil can be imbibed, but not released when the polymer is saturated or squeezed. The polymer can expand up to six times its volume during the sebum-absorbing process. This is one of the few proven technologies that can decrease the appearance of facial sebum but it is not botanically based; however botanicals can be added to the formulation to make a claim. There is some preliminary evidence that niacinamide can reduce sebum production, but further study is warranted. Basically, there is no true botanical that can reliably reduce sebum.

ANTIPERSPIRANTS CONTAIN CHEMICALS THAT ARE NOT NATURALLY DERIVED AND ARE THEREFORE DAMAGING TO THE SWEAT GLANDS

Metal salts of aluminum and/or zirconium form the active agent in all commercially marketed antiperspirants, which are considered over-the-counter drugs by the US Food and Drug Administration (FDA). Essentially, the metal salt forms a reversible physical obstruction in the duct of apocrine and eccrine sweat glands, reducing perspiration by 40—60%. These aluminum salts have an acidic pH of 3.0–4.2. Thus, formulation is critically important to create an antiperspirant that minimizes skin irritation.

BOTANICALS AND MINERAL COSMETICS ARE SAFE AND DO NOT CAUSE ACNE

Botanicals are plant-derived materials and mineral cosmetics contain pigments derived from rock sources. Botanicals and mineral cosmetics are no more or less likely to produce acne than any other raw materials. They must undergo the same comedogenicity testing and clinical testing as any other ingredient. Their safety must be demonstrated in a cosmetic chemistry laboratory and cannot be assumed Fig. 30.5.

Fig. 30.5 Laboratory testing is critical to determine cutaneous safety

FACE MASKS WITH BOTANICALS IMPROVE SKIN TONE

Face masks are creams or pastes that are applied to the face for a limited period of time ranging from 5 to 30 minutes followed by removal. They largely impart aesthetic benefits to the skin. Face masks can be based on quick-drying polymers, clay, or botanicals. Polymer face masks occlude the skin and have a temporarily moisturizing effect. They are peeled from the face as one sheet. Clay face masks are typically used to absorb oil and are rinsed down the drain. Botanical face masks are dried plant ingredients packaged in a pouch to which water is added to create a paste for facial application. They too are rinsed from the face using water.

The main question here is the issue of skin tone. ‘Skin tone’ is a marketing term that has little dermatologic meaning. Well-toned muscles are strong, quick, and hard to fatigue. These terms do not apply to the skin. I believe that skin tone is a concept combining tactile smoothness, even color, and even texture. I do not believe that the short-term application of botanical face masks can produce this benefit, yet they may provide a pleasant period of aromatic relaxation desirable to some consumers.

ALL NATURAL INGREDIENTS ARE SAFER IN SKIN CARE PRODUCTS

It is hard to know exactly what ‘all natural ingredients’ constitutes. All natural has come to mean actives derived from the plants and minerals of the earth. But isn’t everything we see in our world derived from the plants and minerals of the earth? Something that is chemically altered still has its basis in the plants and minerals of the earth. Thus, this term is basically marketing jargon with little medical credibility. All natural ingredients are not necessarily safer in skin care products. Even poison ivy which causes an intense allergic contact dermatitis is ‘natural’ Fig. 30.6.

Fig. 30.6 Poison ivy is a natural ingredient not considered safe for skin application

NUMEROUS BOTANICALS IN COSMECEUTICALS ARE BETTER

There is an unspoken rule in cosmeceutical formulation that if one active ingredient is good, 20 active ingredients are great. This had led to the botanical cocktails present in many facial moisturizing products. A quick read through the label reveals at least 10 different plant extracts. Why are they all there? Many times the botanical cocktail is purchased from a supplier with the intent to create a pleasant fragrance from the botanical mixture. Other times the cosmetic formulator selects the concoction to meet some marketing or media needs at the time. Botanical cocktails are extremely problematic for the dermatologist who is trying to figure out which ingredient is the cause of a patient’s allergic contact dermatitis Fig. 30.7. For this reason, I typically recommend that my patients avoid facial moisturizers that contain numerous botanical extracts.

Fig. 30.7 Eyelid dermatitis due to a botanical moisturizer where the exact cause would be difficult to ascertain

CLEANSERS WITH GROUND BOTANICAL MATERIALS ARE GOOD FOR DEEP CLEANING PORES

A number of botanical facial cleansers contain ground fruit pits, leaves, or other abrasive substances for the purpose of cleaning the pores Fig. 30.8. In fact it is impossible to clean the sebaceous gland and the duct. Only the follicular ostia of the pilosebaceous unit can be accessed from the skin surface. This means that these facial scrubs can basically only mechanically exfoliate the skin surface and the follicular ostia. Comedonal plugs sticking above the skin surface might be removed, as well as any desquamating corneocytes. It is possible to scrub too hard with fruit pits and induce sensitive skin or milia. For patients who wish to mechanically exfoliate, I recommend one of the scrubs with the dissolving sodium tetrahydrate decaborate granules that wear away with continued scrubbing. This prevents the obsessive–compulsive patient from inducing skin damage.

Fig. 30.8 Leaves are used in botanical facial scrubs to abrade the skin surface and induce mechanical exfoliation

TOPICAL BOTANICAL COSMECEUTICALS MINIMIZE POSTMENOPAUSAL SKIN CHANGES

Postmenopausal skin changes are typically due to a low estrogen state leading to an increase in facial folds and upper lip rhytides. A number of topical botanical preparations have been introduced to minimize postmenopausal wrinkling. These cosmeceuticals contain genistein, an extract of fermented soy, which is structurally similar to human estrogen and can thus bind to some of the same receptors. It is for this reason that genistein has been termed a phytoestrogen and credited with the decrease in cardiovascular disease, breast cancer, and postmenopausal facial wrinkling seen in Asian women.

Two different estrogen receptors are present in the human body, alpha and beta. Soy-derived genistein has lower affinity for the human alpha receptor, but the same affinity for the human beta receptor as endogenous human estrogen. Thus, it can exert end-organ effects when orally consumed. Genistein is also able to inhibit tyrosine protein kinase and magnesium ascorbyl phosphate (MAP) kinase that modulate cell growth and differentiation. These effects have only been observed with ingestion of the fermented soy and not with topical application. It is important to distinguish between findings related to the consumption of a botanical and topical botanical cosmeceutical application.