Provider records sourced from NPPES (CMS National Plan & Provider Enumeration System). Data current as of August 10, 2026.

Dr. John Brian Westerdahl, PHD, MPH, RDN

Individual provider Registered Dietitian · NPI 1518784859

Dr. John Brian Westerdahl, PHD, MPH, RDN is a Registered Dietitian in Simi Valley, California. Practices as a sole proprietor. Licensed in California.

Licensed in
CA
In the registry since
2024
What do these letters mean?
PHD — Doctor of Philosophy
A research doctorate. In healthcare it usually sits alongside a clinical licence.
MPH — Master of Public Health
A graduate degree in population health.
RDN — Registered Dietitian Nutritionist
The current title for a registered dietitian.

See every abbreviation used in this directory →

Practice location Address checks out

543 Country Club Dr Ste B333
Simi Valley, CA 93065-0637
Phone: (805) 722-7958
Show map & directions

Pin is approximate — placed at the ZIP-code centre, not the exact door.

Specialties & licences

Registered Dietitian (primary) Taxonomy 133V00000X · Licence 625522 (CA)

Record details

NPI number1518784859
Entity typeIndividual (Type 1)
GenderMale
Credentials PHD , MPH , RDN
Sole proprietorYes
NPI enumeratedSeptember 25, 2024
Last updated in NPPESSeptember 25, 2024
Certification dateSeptember 25, 2024

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