What you need to know about natural preservatives
Among the most significant trends in cosmetics industry is burgeoning interest in organic and natural products and many cosmetics companies started to capitalize on the trend. One good consequence of this trend is that big corporations with big R&D resources started to research more ingredients and chemicals derived from natural resources. The bad outcome however, is that many companies and individuals are coming up with new formulations that are NOT tested for safety, and label their products whatever they want.
As a brief background, under the Federal Food, Drug, and Cosmetic Act, cosmetic products and ingredients (including preservatives) do not require FDA approval before they go to the market, with the exception of color additives. However, companies and individuals who market cosmetics have the legal responsibility to ensure the safety of their products.
This means companies need to demonstrate that their products are not “…contaminated with microorganisms which may be pathogenic, and the density of non-pathogenic microorganisms is low.”
What does “natural” mean?
FDA has not defined the term “natural” or “organic” and has not established a regulatory definition for this term in cosmetic labeling. That means that each company has its own definition or standard of “natural”. Furthermore, an ingredient’s source (either plants, animals or made in the lab) does not determine its safety (1).
I personally can think of 2 possible way of defining a “natural ingredient”:
1) an ingredient extracted from a natural resource such as plants, animals, minerals through physical means (such as cold pressing)
2) an ingredient extracted from a natural source through chemical processes such as extraction, precipitation, distillation or some biotechnological processes such as fermentation. As per the second definition, the original chemical structure or composition of the ingredient may be altered.
Why preservatives are important in cosmetic formulations?
Preservatives in cosmetics are needed for 2 reasons: to prevent primary microbial contamination during the production and to prevent secondary microbial contamination when the product is in use and microbes can be transferred from the consumer into the product.
Cosmetics products can get contaminated with different types of microorganisms (gram positives bacteria, gram negatives ones, molds, yeasts) that can alter the composition of the product or pose a health risk to the consumer. Pathogenic microorganisms such as Staphylococcus aureus, Candida albicans and Pseudomonas aeruginosa are frequently found in contaminated cosmetics, and they are dangerous!!. They can cause skin and eye infections among other health problems.
Just like we humans need water and food to survive, microorganisms need also water and micronutrients to happily grow. And once they have that comfy environment, they spread out very fast.
That’s why cosmetics products that contain water require protection against the growth of microorganisms: to ensure product and consumer safety.
If the products are based on oils or the product packaging is impermeable to microbes (such as aerosols), they might not need a preservative, but still antimicrobial efficacy need to be tested by manufacturers (2).
How can manufacturers minimize the use of synthetic preservatives?
- One way to reduce the amount of the synthetic preservatives is to formulate at lower pH. One way to achieve this is by adding acidic ingredients from natural sources such as salicylic acid, citric acid, lactic acid.
- Another way is to add so called “chelating agents”: they react with metal ions in the microbial cell wall, which enhances the preservatives’ ability to penetrate and destroy the microorganism. One of the most frequently used chelating agents is ethylene-diaminetetraacetic acid (EDTA).
- Preservative systems consisting of an essential oil and a chemical preservative seem to be a good compromise solution (7).
How about using just “natural” preservatives?
Some natural fragrances used in cosmetics have antimicrobial activity, but they are often used in so small amounts that the effect is very small.
Many oil extracts (such as rosemary, thyme, tea tree and lavender, neem, grape seed oils) have some preservative effects and are called natural preservatives, but again, it is necessary to use high concentrations to obtain some efficient preservation.
Another problem with essential oils as preservatives is their relatively low antimicrobial activity in comparison with the commonly used chemical preservatives (6). A further limitation is the acceptance of the organoleptic qualities of the cosmetic with more than 2% of essential oil.
The biggest problem with these oil extracts is that usually they are microorganism specific, which means they are effective against only certain bugs not to a broad range of them. For example a study on using eucalyptus and salvia oils showed that while the oils have some antimicrobial effect on Staph, they don’t have any effect on Candida albicans (3).
Furthermore, both oils and fragrances are composed of many different chemical components and some are highly allergenic (4). Approximately 6% of the general population has a cosmetic-related contact allergy, mainly caused by preservatives or fragrances (5).
Other materials that can be used as natural preservatives are: salt, sugar, bee propolis, cranberry extract. But again, a caveat here, the natural preservative alternatives might not work as well as the synthetic ones, may change structure or may have some unknown health risk.
Any producer’s main concern in formulating a cosmetic product should be in making sure the product is safe for the consumer, not driven by marketing claims.
My recommendation is to pay attention to the water-based “natural” cosmetic formulations, especially if they promote natural preservatives.
And if they are labeled as “preservative-free”, read that label rather as “heaven for bacteria growth”.
- Maccioni A M, Anchisi C, Sanna A, Sardu C, Dessi S. Preservative systems containing essential oils in cosmetic products. Int J Cosmet Sci 2002: 24: 53–59.
- Steinberg D C. Preservatives for Cosmetics, 2nd edition, Allured Publishing, Illinois, 2006.
- Goossens A, Beck MH ,Haneke E, McFadden JP ,Nolting S, Durupt G, Ries G. Adverse cutaneous reactions to cosmetic allergens. Contact Dermatitis 1999: 40: 112–113.
- Jon J. Kabara (Ed), COSMETIC AND DRUG PRESERVATION PRINCIPLES AND PRACTICE 1984
- Kunicka-Styczyńska, A., Sikora, M. and Kalemba, D. (2009), Antimicrobial activity of lavender, tea tree and lemon oils in cosmetic preservative systems. Journal of Applied Microbiology, 107: 1903–1911.