Food supplements containing tea tree, niaouli and cajeput essential oils: their misuse can pose risks

Derived from the leaves of various Melaleuca species, tea tree, niaouli and cajeput essential oils are contained in numerous food supplements. The antimicrobial properties claimed in aromatherapy books have led consumers to misuse these food supplements as auxiliary therapies to treat certain infections (angina, sinusitis, cystitis, etc.).

As restrictions on the use of food supplements are not harmonised at European level, the authorisation of Melaleuca essential oils in food supplements varies depending on the country. For example, they are authorised in Italy but banned in Belgium.

In this context, ANSES received a formal request to study the risks associated with Melaleuca essential oils in food supplements, as well as the conditions most likely to guarantee their safe use by consumers.

Tea tree, niaouli and cajeput essential oils: health risks depending on several factors

In its expert appraisal, ANSES identified several substances of concern contained in tea tree, niaouli and cajeput essential oils:

For tea tree:

• terpinen-4-ol, a major component having testicular toxicity in rats;
• methyl eugenol, a substance found in very small quantities but considered as genotoxic and carcinogenic to humans;
• ascaridole, a newly-formed substance that appears if the essential oil is not correctly stored; its toxicity is poorly documented.

For niaouli and cajeput: 1,8-cineole, a major component having caused neurological complications in children. It is also found in tea tree essential oils but at lower concentrations.

The results of this expert appraisal showed that:

• for tea tree, the health risk associated with terpinen-4-ol and methyl eugenol depends on the level of these compounds in essential oils, the number of drops consumed, the size of the drops dispensed by the dropper bottles and the body weight of the consumer. Uncertainties nonetheless remain as to the toxicity of ascaridole and its presence in products on the market;
• for niaouli and cajeput: the data on 1,8-cineole are insufficient and do not enable a safe exposure dose to be defined for consumers.

Storage, dosing, avoidance, banning: ANSES’s recommendations for the use of various Melaleuca essential oils

Regarding essential oils extracted from Melaleuca and taken orally:

For tea tree essential oils, ANSES advises operators to determine the maximum number of drops to be taken per day; to do so, they should take into account the levels of terpinen-4-ol and methyl eugenol in these essential oils, the size of the drops dispensed by the bottles, and the body weight of the consumer. Moreover, to prevent the formation of ascaridole, consumers should be informed of the need to store tea tree essential oils in a cool place away from light.

For niaouli and cajeput essential oils rich in 1,8-cineole, ANSES recommends banning their oral administration to children under the age of 30 months and to children with a history of epilepsy or febrile seizures, until more precise toxicological data become available.

Lastly, for children and for pregnant and breastfeeding women, ANSES underlines the absence of specific data regarding the risks associated with the oral intake of these three essential oils and advises against their use. 

Regarding the general consumption of food supplements:

ANSES reminds consumers that food supplements are not medicinal products and should not be used as such. It underlines the importance of:

• talking to a healthcare professional about whether taking a food supplement is appropriate with regard to their state of health;
• avoiding the concomitant consumption of several food supplements;
• reporting the consumption of food supplements and concomitant drug treatments to their doctor or pharmacist, due to the risk of interactions.

Lastly, ANSES reminds healthcare professionals and manufacturers of the need to report to its nutrivigilance scheme any adverse effects liable to be associated with the consumption of food supplement.