Thursday, February 2, 2012

If some essential oils are anti-microbial, why aren't we using them as preservatives?

I regularly get e-mails from readers who have read somewhere or have been told by someone that they can use essential oils to preserve products, so I thought I'd address this question - if our essential oils have anti-microbial properties, why can't we use them to preserve our products?

Because they aren't very good anti-microbials in the sense of being able to preserve our products. They might have some wonderful anti-microbial properties on their own - good at killing yeast or bacteria - but they don't offer enough preserving power to keep our products safe. Let's take a look at the science!

I think it's been established that some essential oils have great antimicrobial abilities. For instance, in this study about using cinnamon and clove oils to combat mold, it was found that "Levels of the oils above 250 ppm and of cinnamic aldehyde and eugenol above 200 ppm completely inhibited mold growth, or permitted only a small amount of growth that never reached secondary metabolism and never produced aflatoxins during the time of this study." This study concluded that "Both essential oils possessed significant antimicrobial effects against all microorganisms tested". This study showed that "EOs from cinnamon, allspice, and clove bud plants are compatible with the sensory characteristics of apple-based edible films. These films could extend product shelf life and reduce risk of pathogen growth on food surfaces." We know that tea tree has some antimicrobial properties. (And finally, click here for a great article on tea tree, thyme, peppermint, and rosemary as antimicrobial agents.) Rather than go on for hours, I think we can call it established that some essential oils have the potential to kill beasties!

But the the ability to inhibit growth or kill the beasties doesn't translate into being able to do this in our products. You might be able to kill ants with Raid, but this doesn't mean that you can use Raid in your products to keep the yeast, fungus, and bacteria away!

For instance, this study exploring the antibacterial potential of Ocimum gratissimum essential oil (clove basil, which contains a lot of eugenol) found that "Liquid and semisolid formulations of the oil were designed in a variety of bases for topical antiseptic medication. The products were evaluated by agar diffusion assay against type strains and clinical isolates from boil, wound and pimples. Remarkable antibacterial effects, higher than those of commercial antiseptic products, were demonstrated at 2% Ocimum oil concentration in some bases. The properties of base into which the oil was incorporated affected its activity. It was more effective in hydrophilic bases than in lipophilic bases. Solubilization and microemulsification grossly reduced its activity." So they found that clove basil had great anti-bacterial properties, but adding it to an oil base (lipophilic base) and emulsifying it grossly reduced the activity.

We also might need a lot of essential oil to be antiseptic, and this might be higher than we want in a product, for safety reasons (do you want 5% or 10% of an essential oil in your leave on product?), for active reasons, or for fragrance reasons.

And this is our problem. It isn't as simple as adding essential oils at reasonable levels in the cool down phase. We have to consider what is water soluble and what is oil soluble. We have to consider that emulsions can mess up the chemical properties of things - one of the reasons we can't make our own sunscreen - and we have to consider solubility. We have to take into consideration that our products are complicated things, and science hasn't found a way to make essential oils work as active preservatives yet!

Want to know more about the picture above? Yes, that really is a beach scene painted on a petri dish with fluorescent bacteria! - click here!

21 comments:

Kourtney L. said...

Thank you for your article. It is nice to hear about the science behind why an essential oil is not a preservative. I heard an acquaintance of mine talk about using cinnamon as a natural preservative, I was surprised and a little unsure that the essential oil would work. I glad to hear the facts about it.

goodgirl said...

And not to mention that most of those -I call them- "active" ingredients are known or suspected to cause and/or enhance allergies. Thus most of those compounds have to be declared according to the EU cosmetics directive and have a maximum allowed dosage in the final product ;).

Sara @Osmosis said...

Hoping you'll do more in your essential oil series. Could you tell me if there are any benefits to lemongrass EO or is it just a nice fragrance?

Susan Barclay-Nichols said...

Hi goodgirl! That's one of the things people forget - there are a lot of allergens and sensitizers in essential oils, and putting in 5% in a product could have disastrous consequences!

Hi Sara! Yep, I'm working on some more posts - I was just taking some time off to work on the Newbie Tuesday stuff!

Hi Kourtney! Send your friend over here. I've got many more studies I can share with him/her!

Susan Barclay-Nichols said...

Hi Sara! I've been doing a ton of research on lemongrass. Very interesting stuff. The short answer - it's more than the fragrance! The long answer - well, that's about four posts long, so far! I'm hoping to get them ready for Sunday or Monday, but I'm working on the video for Newbie Tuesday, so it might get delayed! Thanks for the suggestion!

Sara @Osmosis said...

Thanks Susan! I'm excited to hear what you've found out. I've added it to my most recent deodorant recipe and I just love it!

solquartocrescente said...

I understand why companies do not want to use essential oils.

1) first, each combination of essential oils is specific to each recipe. Manufacturers prefer simplicity.

2) they introduce scent, then it is hard to work with fragrances.

3) it is much more expensive to use essential oils than synthetic preservatives.

4) they have allergens that have to be listed in their labels, even when the essential oils are used at levels safe.

However, I still think they can be an alternative which is safer than synthetic preservatives, which have known toxic effects, but to find out a combination of essential oils that works and has reduced scent is a hell lot of work!

To those interested in working with essential oils: I am working currently and finding one that consists in cynnamon, palmarosa, benzoin resin, geranium, lavender, tea tree, marjoram, other essential oils and certain plant extracts. It really works in challenge tests at less than 1%. The problem is that this has to be optimized for each different recipe.

Susan Barclay-Nichols said...

Hi solquartocrescente. Can you provide me with some links to good studies by reputable groups showing that essential oils can work as preservatives in our products? I can't find any, and believe me, I've tried!

solquartocrescente said...

One example showing essential oils as effective preservatives.
http://www.ncbi.nlm.nih.gov/pubmed/15239707

Just browse pubmed for the effects of essential oils, but remember, if it works for the author it does not mean it works for you, because each formula requires different preservations.

I have replied to this in detail in http://swiftcraftymonkey.blogspot.com/2010/10/preservatives-grapefruit-seed-extract.html

Yes, you can have a weekend full of reading!

Susan Barclay-Nichols said...

I think this is a better place for the discussion on essential oils and preservation, so we'll just have to carry on two discussions. Click here to see the other discussion in the comments section of GSE is NOT a preservative

I admit I'm a bit confused by your argument because you send me a link that ends with "The nature of the formulation in which an essential oil is incorporated as preservative could have considerable effect on its efficacy." - which effectively means, this might not work depending upon the product in which you use the essential oil - and you write "if it works for the author it doesn't mean it works for you..." On the one hand, you've provided me with a study that confirms what I wrote in the post - some essential oils have proven antimicrobial activity in vitro, but they might lose those abilities when introduced into a product. On the other hand, you've just said that I might not get the same results. If the conclusions can't be replicated, then they aren't valid.

Again, you are responsible for providing the studies to me - it's not my job to spend my time browsing PubMed or Ebsco or any other resource I have to do my research looking to prove your point. You haven't proved your point - in fact, you've kinda proved mine by providing a study that notes that the nature of the formulation can affect the preservative. Extraordinary claims require extraordinary evidence, and you have failed to provide that information for me.

solquartocrescente said...

Susan, as I said before, I am not here to prove my point or to refute yours. I am here just giving suggestions, to whoever is interested.

If others disagree, then its fair. This is like in politics or religion, every two have different points of view, and they often clash.

But I am not here for that. Neither I am not here to preach essential oils! I do understand their many limitations.

But I had some good results in my creams, and I wished to share to you and your many readers. If one wants to use essential oils as preservatives, then I can help with some hard work I have done, that others do not need go all the path again.

So, while that is still a work in progress, I can point out that I had good preservative effect against mold from using the essential oils of cynnamon, clove, lemongrass, marjoram, palmarosa, tea tree, lime, lemon scented eucalyptus, benzoin, individualy at 0.8% or combined to less than that. Also olive leaf and aspen aid againt molds.
Against bacteria I have good results with thyme, marjoram, basil, cynnamon and grapefruit seed extract at 3%. And without resorting to essential oils, a tincture at 15% worked for me very effectively. as a single preservative. This is not to prove anything! Its only intended for those interested.

So if anyone is interested in extra information, or if you are interested Susan, please ask. I will post studies with essential oils, when authors have determined their effects and percentages at which they work. But only if that is useful for her/his products. And, we all know, what works in one formulation, might not work in another.

I gladly say that I will never post just to prove myself. I am not here to prove any scientific points. No motivation for that. I leave that for others.

I hope you do not become upset with me. I do like a lot your blog, and think it is a good place of knowledge.

I just felt to add a little bit of something new. If you feel cool about it, I will keep sharing what I find. Otherwise, I will not comment any further on these matters.

ECL said...

HI Susan,
I just read through this blog and comments included. I am just curious about your background. Is it science based? Also, have you performed any tests yourself or are you just going off of the literature that you are able to collect on this particular subject?
Might I also ask what type of body products you use? Do they all have FDA labels on them?

Susan Barclay-Nichols said...

Welcome to the blog, ECL. The answers to your questions are addressed on the blog. I do not have equipment to undertake testing, so I'm reading the literature and summarizing what I've read. As for what body care products I use...a few minutes on the blog will make that answer clear. (As a note, I'm Canadian, so the FDA isn't the regulating body in my country.)

Bob said...

How come there are Natural lotion on the market which use essential oils and other natural preservatives ?
Thank you and keep up your good work :-)

Susan Barclay-Nichols said...

Hi Bob. This isn't a short answer type question, but I'll do my best not to write an essay.

1. There are a number of ways companies can hide a preservative. Look at what they call "parfum", because there are preservatives that are allowed to be listed that way.
2. Or they might use Ecocert preservatives, like Natrapres or Leuicidal that they might call natural, but they aren't based on essential oils.
3. They might use hurdle technology.
4. They might not be selling products with water in them.
5. They might be using preservatives you can't identify. 6. And they might be are using those essential oils as fragrances, not preservatives.
7. They might be not telling the truth. Seriously, do a search for those companies you think are using essential oils in water containing products as preservatives and see the recalls and complaints. (Look up Arbonne and see how well they do with unpreserved products.)

Can you provide me with the names of five companies that use essential oils as preservatives? I will do a search to see what I can find about those companies.

Jim Benefer said...

Hi solquartocrescente,

I wish I had run across this blog several months ago. I am in the process of forming a company to produce a product based on Geranium Essential Oil (and good old H2O). I want the product to be as natural as possible and have spent many hours researching emulsifiers to score a '0' on EWG.org/skindeep but have been working on the belief that I can rely on the antimicrobrial properties of pelargonium graveolens x asperum to keep the mold out.

If you (and Susan) would be willing, I would really appreciate your thoughts on this - I would be more than happy to correspond directly via email too.

Susan Barclay-Nichols said...

Hi Jim. I would suggest reviewing the available research rather than getting our opinions as I would hate for you to base a huge business decision on what information either of us could offer. I personally wouldn't trust any anti-microbial without a solid history of use and a huge amount of evidence to back it. Look at Leucidal as an example of when things don't have a long history...

Omoge said...

Hi Susan , I know this post is old but I found it really useful. Even though i gather from your article that essential oils are not good preservatives, I was wondering if a geranium essential oil will preserve a face scrub containing banana and lemon juice for just a month.

Susan Barclay-Nichols said...

Hi Omoge. As the post says, there are no essential oils that will work as anti-microbials. So no, you can't use them to preserve your product for even a week!

And please don't make that scrub with banana and lemon juice. It is a contamination festival waiting to happen. If you doubt me, smash up a banana and leave it on the counter for a few days. Does it look like something you want to put on your body? Please don't use fresh fruit or veggies in your products.

Norman Smith said...

I like essential oils that smells so good.

Vidyut G K said...

I wonder whether anyone knows of a "good bacteria" sort of approach to cosmetics - we see it with fermentated food preservation. We see it with biological use of microbes to eliminate disease causing microbes in agriculture.