How can I help someone with stage 4 kidney disease with their diet?

40grams protein diet. And low phosphrus diet (no cola, chocolate, hard beans, and dairy) also, low salt diet at 2000 mg sodium or less/ 24hrs and control calories per instructions if diabetes is present. Of course this patient sees a nephrologist and you can get more details from him or her or a dietitian.
Avoid toxins in diet. Avoid sugars, fried foods, vegatable oils like canola & soy, meats that are cured wth nitrates & nitrites, aspartame, splenda, partially hydrogenated vegetable oils, maragarine, soy based products, sweetened beverages like juice & soda, microwaved foods, artificial colors & flavors. All of these products cause damage to the cells, tissues & organs in your body contributing to various diseases.