nutritionist
A nutritionist is an expert in nutrition. That is to say, what you eat or don't eat.
Some nutrition is just one of those issues that holds crucial distinction that is going to require expert advisement about
An Expert Aviator is called an "Ace".
A cultures expert is called an ethnologist.
what ia an expert pilot called
A bully expert is called a bullnation
Such a person is a dietician, being an expert on diet and nutrition.
A grammar expert is called a grammatician or a grammarian.
Expert advice or expert guidance.
An expert in his field is often called a specialist or an authority.
A specialist in the study of nutrition; Source: webnetweb A dietitian (also 'dietician', though 'dietitian' is used consistently by professionals) is an expert in food and nutrition. Source: wikipedia
an expert on China is called a sinologist.