Shiitake mushroom powder supplementation increase antioxidative activity in dogs

Kusaba, A., & Arai, T. (2024). Shiitake mushroom powder supplementation increases antioxidative activity in dogs. Frontiers in Veterinary Science, 11, 1355560. https://doi.org/10.3389/fvets.2024.1355560

Study Background

Age-related diseases in dogs, including obesity and metabolic dysfunction, are increasingly associated with oxidative stress and chronic low-grade inflammation. The authors note that shiitake mushrooms (Lentinus edodes) contain several bioactive compounds with reported antioxidant, immunomodulatory, and hypocholesterolemic effects in other species. This study was designed to evaluate the potential for shiitake mushroom powder to impact liver function and antioxidant activity in healthy dogs.

Study Design

The study involved eight healthy Beagle dogs (four male, four female), aged 1 to 3 years. Four dogs received shiitake mushroom powder daily for four weeks at a dosage of 800 mg/kg body weight. This dose was chosen based on its eritadenine content, providing approximately 0.60–0.65 mg/kg/day of this hypocholesterolemic compound. The remaining four dogs served as untreated controls. All dogs were maintained under the same housing and feeding conditions. Body weight and body condition score (BCS) were monitored, and blood samples were collected at baseline and at the end of the study.

Results

Body Weight and Condition

There were no significant changes in body weight or body condition score in either group by the end of the study.

Metabolic Parameters

• Plasma total cholesterol levels significantly decreased in dogs that received shiitake supplementation (from 128 mg/100 mL at baseline to 91 mg/100 mL at week 4).
• Free fatty acid levels increased slightly in the supplemented group, though the change was not statistically significant.
• Plasma glucose, triglyceride, total protein, insulin, and adiponectin levels did not differ significantly after supplementation.
• Liver enzymes (AST and ALT) also showed no significant change.

Antioxidative Activity

• Leukocyte sirtuin1 mRNA expression increased significantly in the supplemented group (from 0.13 to 0.24, normalized to β-actin).
• Plasma SOD activity increased from 20.2 to 103.0 U/mL in the supplemented group. No significant change was observed in controls.

Authors’ Interpretation and Discussion

The authors interpret the observed reduction in cholesterol as consistent with the known effects of eritadenine, which has previously been reported to influence lipid metabolism by modifying hepatic phospholipid profiles and reducing lipoprotein secretion. They note that while high doses of eritadenine have induced hepatic lipid accumulation in rodent models, no signs of fatty liver or liver dysfunction were observed in this study. Plasma liver enzyme levels remained stable, and body condition did not change.

The authors also suggest that components in shiitake powder may activate sirtuin1, a metabolic regulator involved in lipid metabolism and oxidative stress reduction. They highlight that sirtuin1 activation has been associated with increased fatty acid oxidation and upregulation of antioxidant enzymes such as SOD. Citing prior research, they note that compounds from other mushrooms, such as Coriolus versicolor, have demonstrated similar effects, though the specific active constituents in shiitake were not identified in this study.

Limitations

The study was preliminary in nature and included a small sample size. The authors acknowledge that no placebo was used and that some biological variables such as age and sex were not statistically controlled. Additionally, insulin and adiponectin were measured using antibodies developed for rodents, not dogs, which may limit the specificity of those findings. The authors did not evaluate optimal dosing or test the supplement in dogs with pre-existing metabolic conditions. They also did not assess the microbiological status of the feeding environment, which could influence future studies.

Conclusion

The authors conclude that four weeks of shiitake mushroom powder supplementation in healthy dogs led to a significant decrease in plasma cholesterol and significant increases in antioxidant activity as measured by SOD and sirtuin1 mRNA expression. These results suggest that shiitake may have beneficial effects on oxidative balance and lipid metabolism. Further studies are needed to determine its therapeutic value in obese or metabolically compromised dogs and to identify the active compounds responsible for the observed effects.