Table 1.

Experimental design considerations for human studies

Considerations	Recommendations
Co-morbidities	Record any significant existing or prior medical conditions
Age	Ensure control groups are age matched
Sex	Stroke severity and outcome is often worse in women and may need to be adjusted for (Phan et al., 2019)
Geography	Ensure individuals reside in the same region/country or stratify by location (He et al., 2018)
Food intake	Patients with severe stroke may have reduced food intake, potentially confounding results (FOOD Trial Collaboration, 2003)
Stool consistency	Record stool consistency if possible (Lim et al., 2012; Vujkovic-Cvijin et al., 2020)
Infection	Post-stroke infections are common and should be recorded (Chamorro et al., 2007)
Medication	Existing medication may confound results, patients with a history of antibiotic use in the past six months should be excluded (Forslund et al., 2021; Vujkovic-Cvijin et al., 2020)
Treatment	Treatment given – i.e., Thrombolysis should be recorded and tested for an effect on the microbiota. Surgery likely additionally impacts microbiota and should be noted
Alcohol use/smoking	History of alcohol use and smoking are independent stroke risk factors but may also impact microbiota composition (Hankey, 2020; Vujkovic-Cvijin et al., 2020)