What They Have Never Told You About Tea Tree Oil

There are, as we learned in the previous lesson, a wide variety of chemo-types of M. alternifolia existing with each yielding oils of such different chemistry that researchers needed to spend a lot of time and effort identifying then to allow us to know exactly what exists and which produce the best possible oil profile based on published Standards and market preference.

As you learnt there are three main or cardinal chemotypes and another three minor (intermediate) chemo-types of M. alternifolia. We now know that the 1,8 cineole level can vary from as low as 0,50% to as high as 86%. Studies conducted at the Wollongbar Agricultural Institute in Australia show that the 1,8 cineole concentration is inversely proportional to terpinen-4-ol concentrations (in other words the more 1,8 cineole there is the less terpinen-4-ol there is in the Tea Tree oil).

So, which cineole standard is established and why?

In 1996 the review committee for the Australian (AS 2782) and the identical ISO 4730 Standard evaluated all research available on Tea Tree oil and its constituents. This resulted in the Standard being set at a minimum of 30% for terpinen-4-ol because it is the single largest component of Tea Tree oil used in all research as well as being considered the main active component. They also chose a maximum of 15% for 1,8 cineole to make sure the correct chemo-type had been chosen as you learned in previous lesson.

This earlier Standard specified the ranges for 14 constituents and, as was also mentioned in the last lesson this was used as the basis for the both the current BP and Ph. Eur. Standards.

A paper published in Perfumer & Flavourist in 1996 (available here: PF(1996) 21, 7-10 ) clearly shows that as long as terpinen-4-ol is a minimum of 30% there is no evidence of antagonism (reduced activity) due to the presence of 1,8 cineole at up to 15%.  In fact, there appears to be a slight synergistic enhancement of activity when the concentration of 1,8 cineole was increased ; this is likely to be because 1,8 cineole is  a skin penetration enhancer (increases penetration through the outer layers of the skin).

The market for Tea Tree oil interpreted this slightly differently and misread the information (deliberately to differentiate their oil or by mistake, no one knows for sure) to come to the conclusion that "1,8 cineole is harmful and is therefore undesirable in Tea Tree oil while the highest possible terpinen-4-ol is highly desirable". This led to a new market demand for Tea Tree oil with a minimum of 40% terpinen-4-ol and a maximum of 3% or 4% 1,8 cineole or "T40/C3" and "T40/C4" as it came to be known.

No one really knows exactly who or when this T40/C3 trend started but it grew very quickly in the 1990's primarily driven by a new marketing effort where manufacturers promoted their material with the logo "Pharmaceutical grade" representing a T40/C3 (or T40/C4) product.

It is important to note here that a "Pharmaceutical grade" of Tea Tree oil is only a marketing strategy with no internationally recognized Standard and little or no real science to back it up. However, since this was what the market identified as desirable and they were prepared to pay a small premium to obtain this quality it became the de facto market that still exists today.

Over time this T40/C3 standard became so entrenched in the minds (and to some extent the literature) of Tea Tree oil traders, manufacturers and end-users that efforts were made to produce exactly what the market demanded.

According to Tony Larkman, the CEO of ATTIA, "Australia has bred specific trees that consistently produce T40/C3 or T40/C4 to meet market demand through careful selection and propagation of high yielding tress with this oil profile. There are also terpinen-4-ol chemo-type plants with a T40/C12 profile that produces perfectly good Tea Tree oil but it is all about market demand which drives the selection criteria for breeding and seed production and since the market demand which drives the selection criteria for breeding and seed production and since the market has selected T40/T3, Australian producers stick with this and produce oil that is in demand".

Tony Larkman further commented: "...the real story is that there is that in most wild populations of M. alternifolia, an inverse relationship exists between terpinen-4-ol and cineole as described in Wollongbar study. No one has ever scientifically determined if a high terpinen-4-ol/low cineol is more efficacious than a low terpinen 4-ol/ high cineole Tea Tree oil because there is clear evidence that terpinen-4-ol is the main ingredient as an antimicrobial. The specification in the Standard for the two compounds is still very wide because Standards committees are very conservative and don´t want to exclude the growers of high cineole Tea Tree oil from the market..."

(Tony Larkman, private communication, 2016).

How did this happen?

The first  thing to be aware of is that 1,8 cineole has another common name: eucalyptol because it is the main constituent of a very common and widely used essential oil that is also derived, like Tea Tree oil from an Australian native plant: Eucalyptus oil!.

The people who marketed "T40/C3" said that 1,8 cineole is a skin irritant (i.e. cause symptoms like redness, itchy skin, inflammation or a stinging/burning sensation) despite clear evidence in the 1996 article in Perfumer & Flavourist (PF(1996) 21, 7-10) that this is not the case at concentrations of up to 15%. There is some truth in the fact that reduction of the % of the bio-active ingredient terpinen-4-ol can occur; as the author points out in the article "...1,8 cineole, in concentrations above 15% is undesirable because of the concomitant decrease in terpinen-4-ol..." but other studies have suggested that a minimum 30% concentration of terpinen-4-ol is at least as effective as a 40% concentration and other studies suggest that the synergistic value of 1,8 cineole as a skin penetration enhancer may outweigh the need for higher levels of terpinen-4-ol. More research is needed .

As you can see, a myth was created to drive market demand for low cineole Tea Tree oil which is now so embedded that it will be impossible to change.

As this myth emerged, took root and grew it significantly changed the way the Australian Tea Tree oil farmers produced Tea Tree Oil: they bred, over time, plants that exactly meet the profile today's market demands while also breeding for higher yielding plants. Indeed a line of "ultra-low" 1,8 cineole plants were bred to yield only a trace of 1,8 cineole in the oil however the oil yield is significantly lower making it less viable commercially.

In conclusion:

1. The market demands T40/C3 or T40/C4 Tea Tree oil.
2. Ultra-low 1,8 cineole oil can be produced but this is not profitable.
3. Some 1,8 cineole (eg up to 10-15%) is likely to be synergistically beneficial as a penetration enhancer.
4. Any grower with crops high in 1,8 cineole often does not receive a premium for the product which is often blended with very high terpinen-4-ol/low 1,8-cineole oil to produce what the market demands despite this higher cineole concentration potentially improving the oil through synergistic activity.
5. Most Australian growers, with the assistance of ATTIA, grow plants that are high yielding and have an oil profile that matches both the ISO 4730 Standard and the T40/C3 that the market prefers.
6. "Non Australian producers occasionally purchase seed from seed merchants in Australia who are ignorant of the issue of oil quality- They simply go into the Australian bush and collect seed from trees that the old time bush cutters considered the best. Sometimes they are lazy and don´t test the tree for its oil content and profile before collecting the seed because they don´t care; the overseas buyer ends up with the high cineole (or high terpinolene) seed to their detriment and the seed merchant earns a higher profit.
7. This is an advantage for Australian growers because ATTIA breeds for a high yielding plant that has the desired oil profile which is not sold seed to anyone except Australian members who have signed an agreement to only keep it for themselves.
8. Some non- Australian Tea Tree oil is T40/C4. It all depends on how careful they are with seed selection and of course the good growers who understand the market make an effort to get it right".

(Source: Tony Larkman, Personal Communication 2016).

This topic needs further investigation, but I wanted to give you an idea of how it stands at the moment.