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).
Advice is mainly used with the first meaning, and in this meaning it is a mass noun (that is, it has no plural). The business/legal meaning, however, is a count noun: it has a plural form, advices. Tip 1: there are just two possible forms for the noun: advice and advices.