From Arthritis to Zoster

In one form or another, tea tree oil (Melaleuca alternifolia) has been used for its medicinal benefits for thousands of years. The Bundjalung aborigines of Australia revered a lagoon near present-day New South Wales – where Melaleuca leaves fell into the water and decayed for generations – as a site with phenomenal healing powers.

In 1930, the first modern reference to tea tree’s properties appeared in The Medical Journal of Australia, wherein a surgeon reported the successful treatment of surgical wounds with Melaleuca oil, which cleared skin structure infections as efficiently as carbolic acid (the most popular antiseptic of the time) without injuring the surrounding tissues.

Furthermore, due to its effectiveness as a disinfectant, tea tree oil was included in the first-aid kits carried by all Australian soldiers and sailors during World War II. Indeed, the Australian government exempted Melaleuca growers from military service because the industry was deemed critical to the war effort.

Tea tree oil is effective against multiple bacteria, several fungi, and some viruses, and it may even exert a limited antiparasitic effect (it has demonstrated activity against Sarcoptes scabiei, the mite that causes scabies).

It probably shouldn’t be surprising then – given tea tree oil’s spectrum of potential benefits – that Melaleuca’s advocates would attribute it with healing properties that reach beyond current scientific evidence. One such claim revolves around Melaleuca’s ability to enhance the human immune response.

To cut right to the chase, there are no convincing data to support claims that Melaleuca stimulates the immune system.

According to the American Cancer Society:

“Although no one claims tea tree oil can prevent or treat cancer, some proponents claim the oil can boost the immune system (this might tempt some people to assume that Melaleuca helps fight cancer). Some herbalists claim that tea tree oil can be used as a ‘lymphatic recharge’ for a ‘sluggish’ lymphatic system. Available scientific evidence does not support these claims.” (Italics are mine)
One 1999 study frequently quoted as evidence of tea tree oil’s immunostimulating properties compared terpinen-4-ol (Melaleuca’s active ingredient) with crude oil as a catalyst for white blood cell differentiation. After all, anything that leads to white cell differentiation and activation is technically an immunostimulant, right?
Unfortunately, both the crude oil extract and terpinen-4-ol produced the same degree and type of differentiation in the white cell line – specifically, monocytes – being studied. Hence, it appears that any immunostimulation attributable to tea tree oil is identical to that conferred by introducing monocytes to any other foreign substance: essentially, a nonspecific and innate response to a new antigen.
Alas, most experts believe that tea tree oil’s antimicrobial properties (which are impressive in their own right) stem from the direct actions of its chemical constituents on cell walls and growth characteristics of various microorganisms.
So, although tea tree oil displays activity against a variety of potentially nasty microbes, and even though its pharmacologic attributes make it a useful topical antiseptic, it should not be used as an immunostimulant. In short, Melaleuca has no place (for now) in the prevention or treatment of cancer.

Besides, as little as a few teaspoons of tea tree oil, taken internally, can cause fatal poisoning.