What Do You Call a Registered Dietitian Nutritionist (RDN)?

January 9, 2026 •

4 min read

According to the Academy of Nutrition and Dietetics, the titles Registered Dietitian (RD) and Registered Dietitian Nutritionist (RDN) are legally protected and used by professionals who have met rigorous educational and experiential criteria. The proper way to address an RDN depends on the setting, but generally, calling them a 'dietitian' or using their credentials and last name is appropriate. This guide will clarify the correct terminology and professional distinctions.

Quick Summary

The credentials RD and RDN refer to the same expert nutrition professional who has completed extensive training and passed a national exam. All registered dietitians are nutritionists, but not all nutritionists are registered dietitians. The title 'nutritionist' is not protected in most places, allowing individuals with minimal training to use it. RDNs are uniquely qualified to provide medical nutrition therapy.

Key Points

RDN vs. RD: RDN (Registered Dietitian Nutritionist) and RD (Registered Dietitian) are identical, legally protected credentials from the Commission on Dietetic Registration (CDR).
Title Protection: The title 'nutritionist' is not regulated in most states, and anyone can use it, unlike the protected RDN designation.
Comprehensive Training: To become an RDN, candidates must complete an ACEND-accredited graduate degree, 1,000+ hours of supervised practice, and pass a national exam.
Medical Nutrition Therapy: Only RDNs are legally qualified to provide Medical Nutrition Therapy (MNT) and treat specific medical conditions with nutrition.
Professional Address: The proper way to address an RDN is formally as "Mr./Ms. [Last Name]" or by mentioning their credential, like "Jane Doe, RDN".
Variety of Roles: RDNs work in diverse settings, including hospitals, community health, private practice, food service management, and research.

Understanding the RDN Credential

At its core, a Registered Dietitian Nutritionist, or RDN, is a food and nutrition expert who has undergone a significant amount of education and training. The RDN credential, along with RD (Registered Dietitian), is administered by the Commission on Dietetic Registration (CDR), the credentialing agency for the Academy of Nutrition and Dietetics. The 'N' for Nutritionist was added to reflect the profession's expanded focus on the broader concept of wellness, disease prevention, and evidence-based practice. While RD and RDN can be used interchangeably, they are legally protected titles that signify a high level of expertise and training.

The Path to Becoming an RDN

Becoming an RDN involves a strict, multi-step process to ensure competence and protect the public. The requirements include:

Extensive Education: Candidates must complete a bachelor's or master's degree (a master's degree is required for new credential holders after January 1, 2024) from an Accreditation Council for Education in Nutrition and Dietetics (ACEND) accredited program. Coursework covers subjects like food science, anatomy, biochemistry, and medical nutrition therapy.
Supervised Practice: A supervised practice program, often called a dietetic internship, with at least 1,000 hours of clinical, community, and foodservice experience is mandatory.
National Exam: After completing the education and practice hours, individuals must pass a national board exam administered by the CDR.
Continuing Education: RDNs must complete ongoing continuing professional education to maintain their registration and stay up-to-date with the latest science.

The Critical Difference: RDN vs. Nutritionist

One of the most important distinctions to understand is the difference between an RDN and someone who simply calls themselves a "nutritionist." While all RDNs can be called nutritionists, the reverse is not true. In many states, the title "nutritionist" is largely unregulated, meaning anyone can use it, regardless of their training, education, or credentials. This lack of regulation can lead to unqualified individuals providing potentially harmful advice.


RDNs vs. Other Nutrition Professionals	Feature	Registered Dietitian Nutritionist (RDN)	Uncredentialed Nutritionist	Certified Nutrition Specialist (CNS)
Regulation	Legally protected title.	Largely unregulated in many states.	Credentialed but often less recognized than RDN; scope varies by state.
Education	Minimum master's degree (as of 2024) from an ACEND-accredited program.	Varies widely, from weekend courses to self-study.	Master's or doctoral degree required.
Training	1,000+ hours of supervised practice in clinical, community, and food service settings.	No formal training required.	Supervised practice required, but focus may differ from RDN.
Services	Provides Medical Nutrition Therapy (MNT) and counsels on specific medical conditions. Can bill insurance.	Offers general wellness and nutrition advice. Cannot provide MNT.	Varies by state; may provide personalized nutrition therapy but often not covered by insurance.
Clinical Practice	Qualified to work in hospitals and clinical settings.	Not qualified to provide clinical care.	Scope of practice varies significantly by state and setting.

The Role and Responsibilities of an RDN

RDNs are not confined to a single job setting. They apply their expertise in a variety of environments, from clinical to community and corporate wellness. Their responsibilities are diverse and crucial to public health.

Clinical Settings: In hospitals, outpatient clinics, and long-term care facilities, RDNs work as part of the healthcare team. They assess patients' nutritional needs, diagnose nutrition-related problems, and provide medical nutrition therapy for conditions like diabetes, kidney disease, or eating disorders.
Food Service Management: RDNs can oversee large-scale meal planning and preparation in schools, hospitals, and corporate cafeterias. Their work ensures meals are safe, nutritious, and meet dietary requirements.
Community Health: In public health clinics and government agencies, RDNs develop and implement nutrition programs to promote health within communities, often targeting specific populations such as children or the elderly.
Private Practice: Many RDNs work in private practice, offering one-on-one nutrition counseling tailored to a client's specific needs, budget, and health goals.
Industry and Research: RDNs also work in the food industry for product development, in media as communications experts, and in research to advance the science of nutrition.

Proper Etiquette for Addressing an RDN

When addressing an RDN, it's a sign of respect to use the proper title, just as you would for any other healthcare professional. For formal settings or initial introductions, using "Ms./Mr. [Last Name]" is appropriate. You can also mention their credential, such as "Ms. Smith, the dietitian" or introduce them as "Jane Doe, RDN". Most RDNs are comfortable being called by their first name in subsequent or less formal interactions. If the individual also holds a doctorate, they may be addressed as "Dr.". The key is to acknowledge their professional expertise and training.

Conclusion: RDNs as Credentialed Nutrition Experts

In summary, the question of what to call an RDN has a straightforward answer: they are registered dietitians and credentialed nutrition experts. The RDN and RD designations are identical in meaning and signify a high standard of education and competence. The critical takeaway is that while anyone can use the title "nutritionist," only an RDN has met the extensive legal and professional requirements to provide medical nutrition therapy and other advanced nutrition services. When seeking advice for serious health conditions, ensuring you are working with an RDN is paramount for receiving safe, evidence-based care. Their extensive training allows them to translate complex nutrition science into practical, personalized guidance for individuals and communities alike.

Visit the Academy of Nutrition and Dietetics to find a qualified RDN

Frequently Asked Questions

There is no difference in qualifications or practice between an RDN and an RD. The credentialing body, the Commission on Dietetic Registration, added the 'Nutritionist' to the RD title to communicate a broader focus on wellness and nutrition.

No. While all RDNs are also nutritionists, not all nutritionists are RDNs. The term 'nutritionist' is largely unregulated, allowing anyone to use the title regardless of education or training.

In most states, no. Only a licensed or registered dietitian, such as an RDN, is legally authorized to provide Medical Nutrition Therapy (MNT), which involves counseling on diet for a medical condition.

Choosing an RDN ensures you are consulting with a highly trained, credentialed professional whose advice is based on evidence-based research. This is particularly crucial for managing complex health conditions.

Services from an RDN are often covered by Medicare, Medicaid, and most private insurance plans, especially for the treatment of certain chronic diseases. This is because RDNs are recognized healthcare providers.

An RDN must complete a master's degree (as of 2024) from an ACEND-accredited program, which includes courses in food science, biochemistry, and medical nutrition therapy.

RDNs can be found in a wide variety of settings, including hospitals, private practice, community health programs, food service management, and corporate wellness.