Copper and zinc bioaccumulation and bioavailability of Ganoderma lucidum

Ganoderma lucidum is a widely recognized medicinal mushroom. The bioaccumulation and potential bioavailability of copper (Cu) and zinc (Zn), which are essentials for human health, were analyzed in G. lucidum mycelium and fruit bodies grown in the presence of these metals to test their potential utility as a food dietary supplement. Mycelia grown in culture medium with non-mycotoxic doses of Cu or Zn (25 and 50 mg/kg) were selected for evaluation of the bioavailability of these metals in the gastrointestinal tract by using an in vitro simulated digestion system. One gram of dried mycelium grown in the presence of 50 mg/kg Cu or Zn showed a bioavailability of 19% for Cu and 2% for Zn of the recommended daily intake (RDI). When production of fruit bodies was evaluated, the highest biological efficiency (23%) was reached when the substrate was enriched with 100 mg/kg Cu. Cu and Zn contents obtained either before or after digestion of fruit bodies from all metal-enriched treatments were substantially lower than those from metal-enriched mycelia. The metal bioavailability was also low: 1.5% of the Cu RDI and almost negligible for Zn. The results are discussed in relation to the RDI values exhibited by two commercial supplements. The potential incorporation of these mineral-enriched mycelia/fruit bodies in capsules, infusions, and dietary supplements is evaluated.