The Short Version
This claim is well-supported across multiple credible sources spanning peer-reviewed research, major medical institutions, and academic reference databases. Superstitious beliefs demonstrably influence behavior through psychological mechanisms—anxiety reduction, perceived control, and placebo-like effects—and can produce self-fulfilling outcomes when expectations alter actions in ways that confirm the original belief. The claim's hedged language ("can" and "sometimes") accurately reflects the evidence without overstating the effect.