Ruta graveolens
Answered by: Richters Staff
Question from: Rob Keenan
Posted: Before April 1998

On page 62 of your 1996 catalogue, you say that Ruta graveolens can be eaten to relieve headaches. Is this perfectly safe, as the sap can give skin irritations when exposed to sunlight?

Says James Duke, the eminent botanist and herb enthusiast (in his "Handbook of Medicinal Herbs", CRC Press): "Fresh or dried leaves are used sparingly to season such beverages and foods as cheese, meat, vegetable juice, salads, stews, vegetables, and wine." The oil from the leaves is used "in perfumes, in soaps, and toilet preparations." The U.S. Food and Drug Administration has rated rue "generally regarded as safe" (GRAS). This means that rue is officially considered safe enough to use in food. The oil shows up in many prepared foods such as baked goods, candy, gelatin and pudding. But in these preparations the average maximum use of the oil is below 2 parts per million. If ingested in larger doses the oil is poisonous, and is an irritant when applied to the skin. As you mention, handling of foliage or seeds can cause photodermatitis (skin rashes prompted by sunlight). It gets more serious: it can also cause abortion if ingested in large doses. How to use rue safely? First, stay away from the oil; it is used in commercial food preparations but is not appropriate for home use. Second, use the leaves only, and only sparingly: a couple of leaves at a time is enough. A few ingested rue leaves will not cause photodermatitis because sunlight is required. Third, avoid contact by wearing gloves if you have sensitive skin. For most people, handling one or two leaves will not be enough to cause discomfort. When I visited Greece and Mexico I noticed fresh rue being sold in the markets. The plant is widely used for cooking and is handled without much regard to its dangers. This seems to indicate that these dangers are not particularly serious. We have noticed that handling fresh rue outdoors can cause rashes if we are handling the plant a lot. Inside our greenhouses, however, we have never noticed a problem. The irritant action depends on ultraviolet radiation which is largely screened out by greenhouse coverings. By the way, Duke rates rue at about as dangerous as coffee. He "wouldn’t be afraid to drink two cups a day" of a tea made from rue.

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