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 the business world, please advise is usually used as a polite and businesslike general-purpose phrase for asking the other party to tell, inform, notify, clarify, suggest, etc, some information or issue when it becomes available. Please advise if this answer is suitable. You get the general idea.