Laboratory in a tube: fats and oils

2016-05-23

When studying the label of cosmetic products, they often pay attention only to the active ingredients that make up them. But the base is an active carrier of active substances and determines the speed and degree of their absorption, and also affects the process of their transportation through the skin.

Hans Lautenschläger – Doctor of Chemical and Physical Sciences, is engaged in the development and study of the use of cosmetic dermatological preparations (Germany).

Lipid layer of skin

Before we move on to considering fats of vegetable and mineral origin, we should remember what sebum is.

Sebum (sebum) is a complex mixture of different fat-like substances - lipids. It contains glycerides (more than 40%), free fatty acids (16%), wax esters (up to 25%) and cholesterol, squalene (12%) and cholesterol.

Together with the elements of the protective layers, it forms the lipid membrane of the skin - a protective mantle. Sebum triglycerides are similar to fatty vegetable oils, but oil triglycerides contain more unsaturated fatty acids in bound form. Squalene, which is found in leather, is a pure liquid hydrocarbon, meaning it contains only carbon and hydrogen. It belongs to the group of triterpenes and is a precursor to cholesterol.

Sebum performs several functions. It prevents water loss and drying of the skin, protects against damage from acidic or alkaline environments, and prevents the introduction of bacteria. One of the fatty acids in sebum, linoleic acid, inhibits the activity of enzymes involved in the process of keratinization of skin cells. Thus, we can say that sebum is a natural skin care product, without which it would become dry, prone to damage and cracks.

To the history of cosmetics

A significant part of ancient cosmetics consisted of aromatic oils and ointments, which were obtained from plant and animal fats. They were mixed with infusions of flowers, tonic and healing additives were introduced. In the Mediterranean, olive oil was most often used as a base for cream. Many African tribes use raffia palm oil for cosmetic purposes. In Oceania, fat-containing cosmetics are usually made from coconut oil, which is then mixed with palm and castor oils, animal fat and even cow butter with the addition of mahogany, ginger root, herbs or metal dust. It is believed that the famous ancient physician Galen created a mixture of spermaceti, wax, almond oil and water, called “cold cream”. For centuries this was the only cream.

Since then, the recipes and consistencies of creams have undergone enormous changes, but the basis of all modern skin care creams remains, as in ancient times, the composition of fatty substances, water and biologically active components.

Various origins

Among the oils and fats that make up cosmetics, hydrocarbon bases are distinguished.

In the plant world, hydrocarbons are quite common - these are squalene, terpenes (camphor, menthol, citral) and low molecular weight, partly even gaseous substances. Beeswax, as well as plant waxes - herbal wax, carnauba wax and fruit peel wax - contain hydrocarbons with various components: in addition to paraffins, unsaturated terpenes and substances similar in composition are often found. Saturated and inert hydrocarbons are an exception.

Mineral hydrocarbons include such saturated and inert hydrocarbons obtained from petroleum and rock wax as paraffin (solid), paraffin oil (thick and liquid) and petroleum jelly (semi-solid). They are distinguished by a wide variety of individual elements, are extracted from petroleum by fractional distillation, extraction and hydrogenation, and are also freed from carcinogenic and human genome-altering components.

Benefits of herbal ingredients

Why is it preferable to use vegetable oils instead of inexpensive mineral hydrocarbons for the production of cosmetic products?

• Vegetable oils are not foreign substances and easily combine with the structure of skin substances, as a result of which they can also be broken down.

• Vegetable oils contain acids with physiological properties.

• Most vegetable oils contain phytosterols, which are very similar in structure to skin cholesterol. Other natural supplements with beneficial functions may include vitamins, such as vitamins B and E.

• Plant triglycerides smooth skin and moderately reduce TEWL levels. This means that the skin can also “breathe”.

For medical purposes

Highly purified fractions have found application in medicine in the form of ointment and suppository bases. The skin's sensitivity to them is always excellent, although white petroleum jelly in its pure form has a significantly increased coefficient of acanthosis (an increase in the number of spiny epidermal cells in its germinal layer), which can lead to thickening of the epidermis.

An increased coefficient of acanthosis is also observed in some plant triglycerides when they are applied to the skin in their pure form, in particular this applies to castor oil. Of course, in practice, 100% oils and fats are used only in very rare cases, so such data are rather relative.

Vegetable oils have certain advantages over mineral hydrocarbons. They have a multifactorial effect, which differs depending on the type of vegetable oil. The disadvantage of unsaturated vegetable oils is that they are sensitive to atmospheric oxygen. Therefore, they need stabilization with antioxidant vitamins and their derivatives.

In addition, preparations containing water have a very limited shelf life, since they undergo a very slow process of breakdown of triglycerides, which can manifest itself in a change in odor properties.

High stability

Paraffin oils and other substances similar in composition have high chemical resistance to atmospheric oxygen, water and microbial destruction. However, mineral hydrocarbons are not biologically active substances. They are used in the manufacture of durable products that do not require large production costs and are primarily focused on smoothing the skin. It should be noted that mineral oils do not help restore the damaged skin barrier. What exactly does the concept of “restoration” mean in this context? In cosmetology, this concept means the restoration of the skin on its own (endogenous restoration). There is no doubt that mineral hydrocarbons lead to external (exogenous) restoration: mineral oils and petroleum jelly can be introduced dropwise into the upper protective layers, especially in cases where the barrier is damaged, in particular dry skin.

In the future - flabby skin

Yet the superficial restoration of the protective layer does not correspond to natural physiology. It certainly leads to the desired reduction in transepidermal water loss (TEWL) and skin hydration. Due to its surface film formation, Vaseline exhibits the strongest effect and a significant reduction in TEWL levels. However, if an impermeable film is applied to dry skin, it prevents the increase in the synthesis of epidermal fatty acids. Thus, the natural stimulation of DNA activation is disrupted.

Other substances that greatly reduce TEWL levels have a similar effect. This also explains the practical experience when women who use creams with a high content of mineral oils predominantly assess the condition of their skin as very dry, which is a consequence of underdeveloped self-healing of the skin.

Mineral oils are not absorbed by the skin as well as vegetable oils. The relatively rapid absorption of vegetable oils is facilitated by the enzymatic breakdown of triglycerides into individual components (glycerol and fatty acids). When mixing mineral and vegetable oils, mineral hydrocarbons are enriched in the surface layers. In this case, the feeling of smoothing the skin lasts longer, which is an advantage from the point of view of both application technique and skin sensitivity. However, as a result, the natural balance is disrupted and the skin’s readiness for self-healing is reduced. When TEWL levels are significantly reduced, epidermal cell maturation slows down and the layer that protects the skin from acids is damaged.

Based on the above, the use of natural fats and mineral oils serves different purposes. If we are talking exclusively about protecting the skin, you can choose options for using mineral oils that are beneficial both from the point of view of economy and sensory perception. However, it is important to understand that over time the skin will become more slack. In recent years, cosmetology has defended the point of view according to which it is necessary to maintain the highest possible readiness of the skin for self-healing.

Silicones and similar hydrocarbons

Similar paraffin products are microcrystalline wax and mineral mountain waxes ozokerite and ceresin. They are used in the same areas as Vaseline. Another interesting group of substances with similar properties are synthetic polyalphaolefins (PAO). The basis for the production of these substances is also oil, from which they are extracted through the so-called cracking process. RW is not a mixture of substances, but completely homogeneous hydrocarbons without unnecessary impurities. The Acceptable Daily Intake (ADI) for polyalphaolefins is higher, which is why these substances are also used to make lipsticks.

When we talk about lubricants (emollients) in cosmetology, silicones are often mentioned along with mineral oils. Silicones are a fairly large group of synthetic substances. It includes volatile and liquid substances that allow the best distribution of cosmetic preparations over the surface, as well as high-molecular substances. On the one hand, silicones do not have an irritating effect, but on the other hand, like mineral oils, they form a film on the surface of the skin. They exhibit a more pronounced leveling and adhesive effect than mineral oils.

Silicones are used in preparations for external use due to their good tolerance, do not cause skin reactions and are considered reliable. The high efficiency of the substance allows you to use only small doses of silicone to obtain the desired result. First of all, consumers highly appreciate the hydrophobic effect of the substance while simultaneously achieving a velvety effect on the skin. Silicones, like mineral oils, do not take part in maintaining the balance of substances in the physiological aspect. This means that the pleasant sensation does not actually correspond in any way to the actual endogenous restoration of the skin.

The storability of silicones is practically unlimited, since these substances are not subject to either the chemical effects of oxygen in air and water, or microbiological effects on a significant scale.

Portability Comparison

Vegetable oils are one of the permanent components of food, and therefore are not critical for the human body. If mineral oils are ingested in small quantities over a long period of time, for example when using lipstick, then long-term tolerance is of primary importance.

Cases of granulomatous changes in the digestive tract have been described with long-term use of laxatives containing paraffin oils. Since the requirements for product quality are constantly increasing and the exact composition of the oils used in the experimental conditions is not fully known, these data are not statistically representative. There is also a known case where inhalation of aerosols led to the development of pneumonia (pneumonia).

It should be critically noted that the use of certain particle sizes of all substances that cannot be broken down in the human body may lead to similar reactions. In other words, the occurrence of these reactions does not necessarily have to be associated with the use of mineral oils. For this reason, the use of aerosols with components that cannot be broken down in the human body is not acceptable in cosmetology.

Paraffin hydrocarbons and silicones are absorbed by the body orally or through the skin in small quantities. Since they do not take part in metabolism, they can be deposited in fatty tissues or excreted from the body unchanged. To this day, cosmetics manufacturers have no obligations in this regard.

Analyzing all the pros and cons, you need to clearly understand the effect of oils and fats on the skin. As you know, skin is a substrate for natural microflora. Thanks to lipase and esterase, which are contained in the skin, triglycerides are broken down into free acids. This creates a low pH level, which protects the skin from external infections caused by pathogenic bacteria. Occlusive conditions significantly change the microflora. Therefore, in order to maintain the balance of skin microflora, it is preferable to adhere to a physiological strategy in skin care and use vegetable oils to soften the skin. From the point of view of modern corneotherapy, for the manufacture of cosmetic preparations it is also necessary to give preference to natural oils and fats, even if the organoleptic properties, such as skin smoothing, are sometimes inferior to substances from petrochemical raw materials with prolonged use.

Finding compromises

Sometimes it happens that even for concepts for manufacturing products without the use of mineral oils, a compromise must be found due to technical features. Thus, long-chain hydrocarbons of mineral oils or silicones are still indispensable pigment agents in the manufacture of abrasion-resistant, waterproof and elastic camouflage cosmetics. Alternatively, lightweight foundations containing pigments can be made using plant triglycerides.

When deciding whether to use natural fats or mineral oils, it is again necessary to clearly understand the goal - whether the product will provide solely protection to the skin or increase its ability to heal itself to the maximum extent possible.

Thus, in modern cosmetic preparations, oils and fats begin to play the role of active components that interfere with physiological processes in the skin, while auxiliary functions are transferred to more inert silicones.

When applied to the skin, fats can act as emollients, remaining on the surface of the skin and making it smooth and soft, or they can penetrate into the deeper layers, acting as active ingredients. A wide selection of vegetable and animal fats allows you to create a variety of cosmetics. It all depends on the goal that the developer sets for himself.

First published: KOSMETIK international journal, No. 2(36), 2009, pp.80-84