Beyond Protein: Neurospora crassa as an Underrecognized Dietary Source of Ergothioneine and Spermidine

Neurospora crassa has a long history of human consumption in fermented foods and is now produced by submerged fermentation as a whole-mycelium food ingredient. Its protein, fiber, and safety profile have been established, but two smaller constituents—ergothioneine and spermidine—have received little attention. This narrative review places those compounds in context and reports third-party measurements from one commercial lot of dried N. crassa biomass. The lot contained 0.604 mg/g ergothioneine and 20.3 mg/100 g spermidine as received. Sample moisture was not reported, so dry-weight concentrations could not be calculated. The ergothioneine result is numerically within published dry-weight ranges for N. crassa and several cultivated mushrooms, but different moisture bases and methods preclude a direct comparison. The spermidine result is similar to a published soybean value (20.7 mg/100 g), below a wheat-germ value (35.4 mg/100 g), and higher than values reported for several foods in one survey. Studies in model organisms and observational human studies provide a rationale for further research on healthy aging, but neither compound has been shown to extend human life when consumed in N. crassa. Replicated lot testing, moisture measurement, and bioavailability studies are needed before health claims can be made.