Hi & Welcome. I can understand your concern. Since kidneys handle most of the excretory products from our body, in presence of polycystic kidneys one must have the following dietary measures to retard the further damage like your must: 1. Eat a (mostly) vegetarian diet high in antioxidants which help reduce BP and may help slow the growth of kidney cysts 2. Choose low sodium foods and condiments. Try to eat less than 3000 milli-grams of sodium per day. Low sodium diets help reduce BP and helps slow the progression of the disease. 3. Avoid taking caffeine as it may hasten the progression of the disease by elevating blood pressure. 4. Increase the intake of potassium rich foods which help slow the decline in kidney function 5. Take Omega-3 fatty acids which tend to reduce inflammation and slows the progression of the disease. 6. Eat high fiber carbohydrates: 7. Other precautions like avoid stress as it causes cysts to grow faster by elevating adrenaline. 8. See that you adhere to the prescribed medications for high BP and BP is controlled. Hope the suggestions given above could be useful to you. A feed back is appreciated.