Calamus (Sweet Flag) and Its Safety Concerns

Botanical Information and Traditional Uses

Calamus, also known as sweet flag, has a long history of use in traditional medicine, particularly in Ayurveda and Traditional Chinese Medicine.[3] However, its use is now limited due to safety concerns, primarily related to the presence of beta-asarone, a potential carcinogen.[3]

Chemical Composition and Safety Concerns

Calamus is a perennial, semi-aquatic herb with sword-shaped leaves and aromatic rhizomes.[3] The rhizome is the part of the plant most commonly used medicinally.[3] Historically, calamus has been used for various purposes, including digestive support, respiratory ailments, and nervous system issues.[3] It was also used to aid memory and cognitive functions.[3] Native Americans and European herbalists valued it for similar purposes, often using it to treat colds, fever, and digestive issues.[3] In Ayurvedic medicine, it was used to keep the voice going when reciting the Upanishads.[3]

Regulatory Status and Recommendations

The primary concern regarding calamus is the presence of beta-asarone in its essential oil.[3] Beta-asarone has been classified as a potentially carcinogenic compound by the FDA, leading to a ban on calamus-containing food additives in the United States.[3] The tetraploid variety of Acorus calamus found in India contains a larger amount of beta-asarone (75% to 96%), while the diploid plant, Acorus americanus, found in North America, is beta-asarone free.[3] The European triploid plant is a different chemotype of calamus, with oil containing less than 10% asarone.[3]

Potential Benefits and Modern Uses

Due to the potential toxicity of beta-asarone, the use of calamus and its extracts is prohibited in the United States.[4] Maximum limits for beta-asarone content in food and beverages have been set by the European Commission.[4] Clinical studies are lacking to provide dosing recommendations, and use should be approached with caution.[4]

Varieties and Chemotypes

Despite the safety concerns, some studies suggest potential benefits of calamus, including antioxidant, anti-inflammatory, antimicrobial, and cardiovascular effects.[4] It has also shown activities in epilepsy, diabetes, and Alzheimer's disease.[4] However, due to the lack of clinical trial data and the presence of a potential carcinogen, calamus cannot be recommended for any use.[4]

Conclusion

There are different varieties and chemotypes of Acorus calamus found in different geographical areas.[5] The North American variety (A. americanus) is a fertile diploid species and contains almost no phenylpropanoids, including beta-asarone.[5] A. calamus is a (mostly) sterile triploid.[5]

While calamus has a rich history of traditional use, its safety profile is a significant concern. The presence of beta-asarone and the lack of clinical trial data have led to regulatory restrictions and a cautious approach to its use.