 Tea tree oil is touted as having anti-fungal properties. So what happens when it's put to the test against a variety of fungal infections? Watch the video to find out. Our entire understanding of the cause of dandruff shifted with this landmark article published in 1984. Instead of relying on secondary sources, reviews, editorial opinion pieces, he looked at the primary literature, the original studies, and was amazed to find out how overwhelming was the evidence of the true cause and how it had been ignored because it was so well buried under the mountain of error since some expert in the 1800s put forth some bogus theory. We now know that dandruff is triggered by a fungus that lives and feeds on the human scalp, the two major implications being, first, how alarming it is that some bogus theory can remain in the medical literature unchallenged for a century, despite evidence to the contrary, and second, hey, if it's a fungus, what about trying tea tree oil, which contains components that have anti-fungal activity against a range of fungi? That was based on studies like this, though, where tea tree oil in a Petri dish can fight off pathogenic skin fungi, but you don't know if it works for dandruff, until you put it to the test. 126 men and women randomized the daily use of a 5% tea tree oil shampoo or placebo for a month. The placebo worked a little bit, decreasing dandruff severity by about 10%, but the tea tree oil shampoo worked better, about a 40% drop. Looks like more than 40% from the graph, but that's because they misleadingly started the Y-axis at negative 60. This is a classic deception featured in chapter 5 of the 1954 classic How to Lie with Statistics. The graph should really look like this, which makes the effect less impressive, but it was still statistically significant. Only one patient in the tea tree oil group actually achieved a complete response, the one in the placebo group did as well. Thus it seems that the tea tree oil shampoo would require ongoing application for control of dandruff. Speaking of fungus, what about tea tree oil in the treatment of athlete's foot? That may actually be our most common fungal skin infection, affecting up to 1 in 10. So about 100 patients randomized into one of three groups. A 10% tea tree oil cream, tynactin, an antifungal drug, or a placebo cream. A month later, the fungus was wiped out in 85% of the drug group, but only about a quarter of the placebo in tea tree oil groups. This is somewhat surprising, since tea tree oil can kill off the fungus in a tea tree dish, but apparently not on toes. That reminds me of some of the oral health data on tea tree oil. I can wipe out some oral pathogens in a tea tree dish, but have people swish a tea tree oil solution around their mouth. And here's the dental plaque buildup after four days of no brushing, swishing with a placebo. Here's swishing with a medicated chlorhexidine mouthwash, which helps keep the plaque a bit at bay. But the tea tree oil mouth rinse has no effect, so if tea tree oil doesn't influence the amount of plaque, presumably it wouldn't help with gingivitis, the gum inflammation that's caused by plaque buildup. But no, here's the twist. True, no reduction in plaque with a 2.5% tea tree oil gel, yet significant reduction in gingivitis scores. Since decreased gum inflammation occurred without a decrease in plaque, it appeared to just be helping more from an anti-inflammatory, rather than anti-microbial mechanism. Might the same thing be happening here? Yeah, from a mycological cure standpoint, a fungus cure standpoint, tea tree oil didn't really do any better than placebo. But though the drug wiped out the fungus in 85% of cases, in some of those cases, the patient actually didn't notice an improvement in symptoms, or they actually felt worse after the drug, probably a reflection of tinnactin's irritant side effects. If instead of mycological cure, you looked at symptom improvement, tea tree oil works as well as the drug. So this may be the basis for the popular use of tea tree oil in the treatment of athlete's foot. But people should realize it's just symptomatic relief, and they're not necessarily eliminating the underlying clause. Of course, maybe they didn't use a strong enough concentration, and indeed, if you go with not a 10% cream, but up to 25 or 50%, you can get mycological cure rates above that of placebo, but still not as good as the drug. And in those high concentrations, some of the patients applying tea tree oil developed moderate to severe dermatitis. They broke out in a rash. But hey, if you have a patient that doesn't want to use the medicated creams, then a 25% tea tree oil application has a decent chance of knocking it out without being too risky, but the standard over-the-counter antifungal creams may work better. Onchomycosis is a fungal infection of our nails, usually toe nails, but sometimes fingernails, characterized by nail discoloration to form the detachment, thickening, crumbling, ridging. Here's an example of what it can look like. Reported prevalence is estimated to be about 125 people, though it's more common in older individuals, 1 in 5, over 16, and like half of 70-year-olds. Unfortunately, it's really hard to treat because the fungus can hide deep inside the nail, protected from the blood supply on one side, or anything you want to put on topically on the other. So recurrence after treatment is common due to residual fungus, even if you're able to beat it back. Many of the oral systemic treatments can be toxic, and many topical applications require long treatment courses, which may limit patient compliance, especially in patients who want to use nail polish or something to cover it up. So, given all the problems with a lot of prescription antifungals, there has been renewed interest in natural remedies. Well, if tea-troyal can affect athlete's foot and dendro fungus, what about nail fungus? Well, there was this study of a combination of the antifungal drug in Lothriman cream with tea-troyal that seemed pretty effective compared to nothing, but what about compared to each other? Well, there was one head-to-head study comparing tea-troyal with a common antifungal drug, a double-blind, randomized, controlled trial, twice-daily application of either the drug or pure tea-troyal on the nail for six months. Debringment was performed every few months where some of the fungal mass is debulked, scraped, ground off, and after six months, the drug only wiped the fungus out completely in about one in 10 cases, but looked better with partial full resolution of the appearance in the majority of patients, either from the doctor's assessment or the patient's. And the tea-troyal did just as well. The two preparations were comparable in efficacy of cure clinical assessment and subjective improvement, even though cost was comparable. So for patients desiring a natural treatment for athlete's foot or nail fungus, topical tea-troyals are a reasonable alternative to prescription or over-the-counter antifungals. Speaking of natural treatments, how about a truly natural treatment? You know, one potential reason for the poor long-term benefits of any therapy for nail fungus is that it may only be treating a manifestation of underlying disease, such as generalized immune suppression or peripheral micro or macrovascular disease. Maybe fungal nail infections are just a manifestation of poor peripheral blood circulation that would normally allow your body's natural defenses to keep the fungus from taking root in the first place. Evidently, there was a non-English language study of 400 patients that looked at the relationship between blood circulation of the skin and development of fungal disease. That was the title, and found a greater than 50% reduction in blood flow in patients with athlete's foot and nail fungus, compared with patients without these disorders. So if fungal nail infections are just a symptom of an underlying process, then treatment named it a eradication of a pathogen may be unrealistic. No wonder it just grows right back. A more appropriate goal then may be to just give up and live with it. But wait, if it's a circulation problem, why not instead improve the circulation? We've known since the 1950s that you can effectively switch peripheral artery circulation on and off like a light switch within days by switching people between a low-fat plant-based diet and a more conventional diet that contributed to the problem in the first place.