‘Natural’ Doesn’t Necessarily Mean ‘Safe’ with Supplements like Senna
A national survey by the Centers for Disease Control found that botanical dietary supplements are used frequently by adults and children. Because dietary supplements are regulated as food rather than drugs, safety and efficacy guidelines are less rigorous than for pharmaceutical products. As a result, there are often no studies on the hazards of using the supplements before marketing them. Botanical supplements like senna have been reported to contain contaminants including metals, molds, and pesticides.
Senna is a dietary supplement made from two plants, Alexandrian senna (Cassia senna L) and Tinnevelly senna (Cassia angustifolia Vahl). The plants are naturally found in Egypt and India and are used as a laxative. However, as a dietary supplement, little is known about its health side effects, including on reproduction and whether it causes cancer. Because of senna’s wide use and the lack of laboratory studies on its safety, the United States Food and Drug Administration partnered with the National Toxicology Program (NTP) at the National Institute of Environmental Health Sciences to study senna’s toxicity.
Analyzing Compounds Found in Senna Supplements
The RTI Natural Products Laboratory isolated compounds from senna pods and several senna-based supplements. Our specialized laboratories allow us to extract and purify chemical substances from plants and to determine their structures, identifying harmful impurities that make up as little as 0.1 percent of the product. We use advanced liquid chromatography to separate the complex mixture of chemicals extracted from plant samples and obtain pure compounds for additional analysis. Nuclear magnetic resonance (NMR) spectroscopy and high-resolution mass spectrometry allow us to piece together the chemical structure of the compounds isolated from the supplements. Extensive chemical structure libraries give us the highest confidence in our identification of the chemicals. We have used similar techniques for more than 50 years for natural product analysis, including the characterization of cancer treatments Camptothecin and Taxol.
Identifying the constituents in the senna powder helped NTP to design pre-clinical toxicity studies, which found that the supplement was not linked to cancer but could damage the gastrointestinal tract when overused. The major chemicals identified in senna supplements are called “sennosides,” which are the active laxative compounds; we also isolated several other minor chemicals from the samples. In all, we were able to identify 9 out of the 11 chemicals isolated against known compounds, allowing our collaborators to successfully carry out toxicity studies of the supplements.
Dedicated to Protecting Public Health by Evaluating Supplement Safety
RTI has been a trusted partner of the NTP since 1984 through our chemistry services contract. We provide support to NTP studies by analyzing chemicals and biological samples to inform their findings. Studies on the safety of senna supplements and other products allow RTI to provide critical context to government regulators, informing their decisions on whether to remove products from the market. This work shows RTI’s ongoing commitment to providing reliable scientific information to support regulatory decisions and promote public health through informing consumers on product safety.