a person who is a specialist in a particular subject and whose job is to give advice

treats health issues brought on by immune system problems.

someone who has a lot of experience, knowledge, or skill in a particular subject

someone who studies a subject, especially in order to discover new information or reach a new understanding

a dentist who specializes in the prevention, diagnosis, and treatment of periodontal disease

someone involved in a skilled job or activity

a person who advises others on matters of food and nutrition and their impacts on health.

a scientist who studies the chemical and physical principles of living things and of biological processes such as cell development, growth, and heredity.

a medical doctor who specializes in diagnosing and treating disease and injury, using medical imaging techniques

a person who teaches people

an expert in identifying and treating disease-related malnutrition and in conducting medical nutrition

a person who gives others advice or guidance