Table 1 Summary of assessments and testing instruments used in the NutBrain Study

 Health and socio-demographics

Written questionnaire developed by the researchers regarding: socio-demographic information, household income, family history of diseases, medical conditions, surgery and illnesses, use of drugs and supplements, hospitalization, menstrual gynaecological history, and smoking habit.

 Physical Activity level

International Physical Activity Questionnaire (IPAQ) [45]

 Cognitive reserve

Cognitive Reserve Index questionnaire (CRIq) [46]

 Functional status

Instrumental Activities of Daily Living scale (IADL) [47]

Katz Index of Independence in Activities of Daily Living (ADL) [48]

 Depression

Center for Epidemiologic Studies Depression (CES-D) scale

 Height

Portable wall-mounting stadiometer SECA 213

 Weight

Homologated electronic scale Tanita SC240MA

 Waist and mid-upper arm circumferences

Flexible graduated measuring tape SECA 201

 Fat mass (FM%) and Total Body Water (TBW%)

Bioelectrical impedance analysis (BIA) (Tanita SC240MA)

 Blood

Cells, plasma and genomic DNA (for APOE genotyping)

 Stool

Alpha- and beta-diversity measures, bacterial relative abundances (indexes estimated on the 16S rRNA-based sequencing data)

 Blood pressure

Sphygmomanometer

 Heart rate

Heart rate monitor

 MRI scans

Siemens MAGNETOM 3 T scanner

 Dietary habits

Semi-quantitative food frequency questionnaire (SFFQ) [49]

Estimated 3-day food diary

 Malnutrition

Mini-nutritional assessment (MNA) [50]

 Global cognitive function:

MMSE [51]

Memory

Free and Cues Selective Reminding Test (FCSRT) [52]

Logical Memory test – Babcock Test [53]

Rey-Osterrieth Complex Figure Test (ROCF) – delay recall [54]

Execute function

Frontal Assessment Battery (FAB) [55]

Phonemic and semantic verbal fluency [56]

Trial Making Test (TMT A and B) [57]

Language

Picture Naming Test [58]

Visuo-spatial abilitities

Rey-Osterrieth Complex Figure Test (ROCF) – copy [54]