Chaparral, formally known as Larrea tridentata, is a resilient flowering shrub native to the arid desert regions of North America, spanning the Southwestern United States and northern Mexico. It is commonly recognized as creosote bush or greasewood due to the distinctive, pungent, resinous coating on its leaves. For centuries, indigenous cultures have utilized this plant for its purported medicinal qualities, establishing a long history of folk use. Despite its traditional roots, the internal use of chaparral is now a subject of modern health debate and regulatory concern.
Traditional Applications and Folk Uses
The history of Larrea tridentata in folk medicine spans thousands of years, primarily among Native American and Indigenous Mexican communities. Traditionally, the leaves and stems were prepared as a tea or infusion to address internal conditions. These preparations were often used by practitioners as a “blood purifier” or general tonic intended to promote overall wellness.
Internal uses included treating respiratory infections, such as colds and coughs, and addressing various gastrointestinal complaints like diarrhea and stomach cramps. Decoctions were also used traditionally for conditions such as tuberculosis and other intestinal issues. Chaparral also gained a reputation in folk practice for managing symptoms of rheumatism, arthritis, and even diabetes.
Chaparral was a popular topical agent for external applications. Poultices and washes made from the leaves were applied directly to the skin to promote the healing of minor wounds, burns, and sores. External use was also extended to treat various skin conditions, including eczema and fungal infections. It was also used to alleviate the pain and inflammation associated with stiff limbs or rheumatism.
Key Bioactive Components and Scientific Status
The primary focus of scientific interest in chaparral lies in a potent compound called Nordihydroguaiaretic acid, or NDGA. NDGA is a phenolic lignan highly concentrated in the plant’s resin, sometimes accounting for up to 10% of the dry weight of the leaves. This compound is recognized for its powerful antioxidant activity, which is theorized to be the mechanism behind many traditional anti-inflammatory and anti-aging claims.
NDGA works by scavenging free radicals, suggesting a strong protective effect at the cellular level. Its ability to inhibit lipid peroxidation, a process where free radicals attack cell membranes, demonstrates its potent antioxidant capacity. This capacity led to NDGA’s historical use in the United States, beginning in the 1940s, as a food preservative to stabilize oils and edible fats.
Despite promising results in laboratory and animal studies showing NDGA’s potential for anti-tumor, anti-inflammatory, and antiviral effects, conclusive human clinical trials are largely absent. NDGA lost its “Generally Recognized as Safe” (GRAS) status with the U.S. Food and Drug Administration (FDA) in 1968. This regulatory action was taken due to concerns about its potential for toxicity following long-term ingestion in animal models. Scientific research has since focused more on the compound’s negative biological impact rather than validating its folk uses.
Safety Profile and Toxicity Warnings
The potential for serious health risks associated with the internal consumption of chaparral is a primary concern, particularly regarding its effect on the liver. Numerous reports have documented cases of hepatotoxicity, or chemically induced liver injury, linked directly to the ingestion of chaparral products. The resulting liver damage often presents as acute hepatitis, characterized by symptoms such as jaundice, fatigue, and elevated liver enzyme levels.
In some cases, chaparral consumption has progressed to acute liver failure, requiring emergency medical intervention. The mechanism of this toxicity is not fully understood but is widely attributed to the bioactive compound NDGA and its subsequent metabolites. Toxicity can manifest after daily ingestion for a period of three to twelve weeks. Furthermore, the severity of the damage does not always correlate directly with the amount or duration of use.
Regulatory bodies in North America have issued warnings regarding the use of this herb. The FDA has advised consumers against the internal use of chaparral due to numerous reports of liver damage. Health Canada has also warned consumers to avoid products containing Larrea species because of the documented risk of harm to the liver and kidneys. Health professionals consider chaparral “likely unsafe” when taken by mouth. Individuals with pre-existing liver conditions, those who are pregnant or nursing, and people taking other hepatotoxic medications are advised to avoid chaparral entirely.