Some people with liver disease must eat a special diet. This diet helps the liver function and protects it from working too hard. Proteins normally help the body repair tissue. They also prevent fatty buildup and damage to the liver cells.
Advise is a verb, and advice is a noun. So advice is what is given, while the act of giving advice is called advising (or to advise).
In some countries, legal advice is subject to the possession of a specific licence; in others, it is simply subject to the general regulation of professional obligation and can be provided by any person, who will usually be legally responsible for the provided advice.