Time to learn about carvone

Caraway seeds contain carvone (Photo: Wikimedia)

Caraway seeds contain plenty of carvone (Photo: Wikimedia)

To be brutally honest I have never heard of carvone before, have you? Maybe it’s time to get better acquainted with this chemical compound, at least that’s the view of the Scientific Committee of the European Food Safety Authority.

It is not that it hasn’t received attention before from different bodies, initially by the Joint FAO/WHO Committee on Food Additives (JECFA) between 1968 and 2000, then as a pesticide active substance by the European Commission in 2008, then by the EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids (CEF) in 2011 and the latest evaluation by EFSA’s Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) in 2011.

So why a renewed attention now?

Carvone can be found in many places

Let’s first have a look at what carvone is since it is a little complex. Carvone is a member of a family of chemicals called terpenoids. It is a natural component in several food items such as mint and caraway but it may also be used as a pesticide, food and feed flavouring, in personal care products, or, together with other active substances, as a zootechnical feed additive. So it could be expected to be around a fair bit.

There are actually two varieties of carvone that are mirror images of each other, R-(-)-carvone (also called l-carvone) and S-(+)-carvone (also called d-carvone), which can be recognised by their smell. R-carvone smells like spearmint and S-carvone smells like caraway so there is no price for guessing that R-carvone is a principle component of oils extracted from several species of mint and S-carvone a principal component of caraway seed oil and also dill seed oil and mandarin peel oil.

Caraway is one of the oldest herbs cultivated in Europe and was used for medicinal purposes by the ancient Romans without knowing about the specifics of carvone. As the compound most responsible for the flavour of caraway, dill and spearmint, carvone has been used for millennia in food. Both carvones are now used in the food and flavour industry. Wrigley’s Spearmint Gum is soaked in R-carvone and powdered with sugar.

S-carvone is used to prevent premature sprouting of potatoes during storage while R-carvone has been proposed for use as a mosquito repellent. R-carvone is also used for air freshening products, in personal care products, in aromatherapy and in alternative medicines.

So what is the problem?

A little bit tricky since toxicity results are available only for S-carvone and we are exposed to much higher levels of R-carvone, about three times more. Although experimental animals died when given very high levels of S-carvone, more realistic dose levels caused damage to the liver. The Scientific Committee opinion used the liver damage to establish an Acceptable Daily Intake (ADI) of 0.6 mg/kg body weight per day for S-carvone, using an uncertainty factor of 100 based on the experimental animal results. An ADI for R-carvone could not be established because of the previously mentioned lack of toxicity data.

Question then is if we get close to the ADI for S-carvone and what to do with R-carvone. As a matter of fact children with the highest exposure to S-carvone come very close to the ADI. The largest contributors are food flavourings, personal care products and natural spices. The much higher intake of R-carvone, especially for adults, come from personal care products followed by food flavourings.

Toothpaste among the largest contributors to carvone exposure (Photo: Brandon Cripps)

Toothpaste among the largest contributors to carvone exposure (Photo: Brandon Cripps)

One culprit in particular is toothpaste followed by mouthwash. Carvones are commonly added to such personal care products. Toothpaste commonly contain 3-10% spearmint oil (80% R-carvone) which corresponds to an average content of 52,000 mg R-carvone/kg toothpaste + 1-2% dill or caraway oil (60% S-carvone) which corresponds to an average content of 9,000 mg S-carvone/kg toothpaste.

The carvone content in mouthwash has been estimated to be 1.5% R-carvone, which corresponds to 15,000 mg R-carvone/kg mouthwash.

Still uncertainties

Consumption of S-carvone seems to be within the ADI and safe for most people as long as there are no cumulative effects from simultaneous consumption of R-carvone. And this we will not know until results are in from further experiments.

So stay tuned and in the meantime you should probably continue to brush your teeth.


2 thoughts on “Time to learn about carvone

  1. Thanks for this interesting post as I never appreciated the organoleptic differences between R and S forms of carvone nor the potential toxicity of S-carvone. I did want to point out another less well known relationship and that is between caraway and cumin, both of which are used as flavoring agents although the history of use of cumin is much older, e.g. it is referenced several times in the Bible. The seeds are similar in appearance and their taste is similar, although clearly different. Cumin was used by the Egyptian, Greeks and Romans, but fell out of use in Europe after the Middle Ages, when it was replaced by caraway. Confusion concerning these two spices continues as “cumin” and “caraway” are terms often used interchangeably. While your post on carvone suggests that cumin may be a safer alternative, I was unable to find any study that looked for the presence of S-carvone in cumin.

    • I agree it is surprising that a slight change in the three-dimensional structure of the compounds can give so different olfactory responses. And now I am confused about caraway and cumin. As it happens what we call “kummin” in Swedish is actually caraway and many other languages seem to have similarly confused the two. You learn something new every day.

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