Scientific investigation of putative health benefits of Ganoderma lucidum

Abstract

Ganoderma lucidum ('Lingzhi') is a popular traditional medicinal mushroom and has long been reputed to increase youthful vigour and promote vitality. Specific reputed effects include anti-cancer, anti-bacterial, anti-inflammatory, antioxidant, lipid lowering, and immunomodulatory effects. However, these putative beneficial effects are not to date substantiated by the literature, and require scientific study. The aims of this study, therefore, were to investigate the putative health benefits of the G. lucidum mushroom using in vitro systems and human supplementation trials in carefully controlled experiments and employing a range of techniques and biomarkers. The primary aim was to investigate the effect of G. lucidum supplementation in healthy subjects, using the biomarker approach, on antioxidant status, coronary heart disease risk, DNA damage, immune status, inflammation, and liver and renal toxicity. This was assessed in three placebo-controlled, cross-over human supplementation trials: an acute post ingestion, 10 days and 4 weeks trials, with blood and urine samples collected from a total of 30 healthy volunteers. A secondary aim was to perform preliminary in vitro studies to explore G. lucidum's antioxidant properties using the FRAP assay, effects on DNA in relation to a standard oxidant challenge using the comet assay, anti-inflammatory properties by the ability to inhibit the enzyme phospholipase A2 and effects on bacterial growth alone and in combination with selected antibiotics. Results showed a significant post-ingestion increase in plasma and urine antioxidant capacity, with peak response at 90min. After 10 days' supplementation with G. lucidum, lipid standardised 帢-tocopherol concentration and urine antioxidant capacity increased (P<0.05). Ascorbic acid and total 帢-tocopherol concentrations and erythrocyte SOD and GPx activities increased slightly but non-significantly with G. lucidum supplementation. Plasma lipids and uric acid tended to decrease, but changes were not statistically significant. In the 4 weeks supplementation trial, no deleterious effects on measured variables were seen, however, no significant beneficial effects were detected. The preliminary in vitro studies showed that G. lucidum possesses antioxidant power and inhibits the enzyme PLA2 from two non-human sources. G. lucidum was also shown to have additive/synergistic effects in combination with two types of antibiotics against the bacteria Staphylococcus aureus but did not show antimicrobial effects by itself. In addition, G. lucidum showed a dose-dependent effect on human DNA in vitro. This comprehensive study of effects in healthy subjects together with the in vitro studies, provides useful, new scientific data that supports some of the health claims of G. lucidum and will support future controlled intervention trials designed to assess the therapeutic effect of G. lucidum in subjects at high risk of chronic, age-related disease.