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).
If you advise someone to do something, you say that you think they should do it. He advised her to see a doctor. He advised me not to buy it. If you say to someone ' I advise you to... ', you are telling them that you think they should do it. The operation will be tiring so I advise you to get some rest.