Sassafras

Sassafras is native to eastern North America. It is a tree that can grow up to 90 feet tall, and it has distinctive three-fingered mitten-shaped leaves, as well as other leaf shapes. The inner bark of the root is used medicinally and in the preparation of beverages.

Sassafras was used by Native Americans for many purposes, primarily for infections and gastrointestinal problems.¹ Sassafras was one of the first and largest exports from the New World back to Europe as a beverage and medicine.² Commercially, the pleasant tasting volatile oil was valued as a flavoring agent in root beer and similar beverages. Eclectic physicians in the late 19th and early 20th centuries considered sassafras a useful diaphoretic (a substance that causes sweating) and diuretic plant, primarily for relieving rheumatism and fevers, and as part of the treatment of urinary tract infections.³

The volatile oil of sassafras is believed to be the major active constituent of the plant. This oil contains up to 85% of the terpenoid known as safrole.⁴ Safrole causes liver cancer when given to laboratory animals in high doses for long periods of time.⁵ Sassafras bark, sassafras oil, and safrole are currently prohibited by the U.S. Food and Drug Administration from use as flavorings or food additives. Human studies are lacking to verify the efficacy of sassafras for any condition. However, one case study has been published showing that sassafras acted as a diaphoretic in an otherwise healthy woman.⁶ While the amount of sassafras that could potentially cause cancer in humans remains unknown, one cup of strong sassafras tea is reported to contain as much as 200 mg of safrole, an amount that is four times higher than the amount considered potentially hazardous to humans if consumed regularly.⁷

The safety of long-term internal use of sassafras has not been proven. Only guaranteed safrole-free products should be consumed. Note that safrole-containing food products are illegal in the United States and Canada.⁸ Some sources suggest a dilute tincture can be used in the amount of 1 to 2 ml three times per day.⁹ Volatile oil of sassafras can be applied topically three times per day for lice, but should never be taken internally.¹⁰

Safrole causes liver cancer if given to laboratory animals “in high doses and for extended periods of time.”¹¹ This requires metabolism of safrole by the liver into other toxic compounds, though the liver also removes some of these compounds for excretion through the urine.^{12, 13} The overall risk of sassafras causing cancer in humans is thought to be low because it is only weakly active and the amounts normally consumed are low.¹⁴ To eliminate the risk, sassafras products that contain safrole should not be consumed.

Safrole and its toxic metabolites do cross the placenta and enter breast milk in laboratory animals, and thus sassafras should be avoided by women who are pregnant or breast-feeding.¹⁵