Evaluation on quality consistency of Reishi dietary supplements collected in the United States

An estimated one hundred millions of Americans spend more than $28 billion on dietary supplements every year. However, under Dietary Supplements Health and Education Act of 1994 (DSHEA), quality of dietary supplements is not evaluated by the U.S. Food and Drug Administration (FDA).Alarmingly, hundreds of products marketed as supplements have been found spiked with illicit substances not listed on the products’ labels, risking serious injury or even death. In February 2015, the New York State Attorney General compelled major retailers – Walgreens, Walmart, Target, and GNC – to halt sales of certain herbal supplements, after deoxyribonucleic acid (DNA) barcoding results failed to detect DNA from the botanical materials listed on the label of ~80% tested products. Though the absence of DNA might be an artifact caused by its destruction during the manufacturing process, it still triggered a great concern on the quality of dietary supplements in the United States. Usually, chemical characters of herbal supplements are more stable than their DNA sequences during different manufacturing processes. Therefore, taking chemical insights into the quality of herbal/mushroom supplements should be more reasonable.

Ganoderma lucidum is a well-known medicinal mushroom which has been used in prevention and treatment of a variety of diseases such as bronchitis, allergies, hepatitis, immunological disorders, and cancer. At present, numerous G. lucidum products have emerged in the form of dietary supplements in the United States and it is also listed in the Dietary Supplements and Herbal Medicines of USP . However, the quality consistency of these products based on their label ingredients has seldom been evaluated due to the lack of a suitable toolkit.

Usually, triterpenes and polysaccharides are considered as the main bioactive components in G. lucidum fruiting body, which have been used as markers for G. lucidum officially recorded in Chinese Pharmacopoeia (2015) due to their anti-cancer and immunomodulatory activities. Recently, in a Sino-us joint study,19 batches of products of G. lucidum (Red Reishi, Reishi), herbal/mushroom supplements purchased in the United States, were evaluated based on their bioactive components including triterpenes and polysaccharides by using a reliable and scientific toolkit including colorimetric assay, high performance thin layer chromatography (HPTLC), gas chromatography coupled with mass spectrometry (GC-MS), saccharide mapping based on polysaccharide analysis using carbohydrate gel electrophoresis (PACE), and high performance size exclusion chromatography coupled with multi angle laser light scattering and refractive index detector (HPSEC-MALLS-RID) method.

The results showed that the measured ingredients of only 5 tested samples (26.3%) were in accordance with their labels, which was similar to the data of DNA barcoding test. Although only 19 batches of products were collected and analyzed, they almost represented the G. lucidum dietary supplements available in USA market. Actually, ten batches are enough for evaluating the quality consistency of tested sample (China Pharmopoeia 2015). The study suggested the quality consistency of G. lucidum dietary supplements in the U.S. market was poor, which should be carefully investigated.

Furthermore, the results also suggested that saccharide mapping based on PACE analysis, and HPSEC-MALLS-RID based on dn/dc had great potential for routine quality evaluation of polysaccharides from dietary supplements.

https://www.nature.com/articles/s41598-017-06336-3