A high salt intake can make kidney function deteriorate more quickly than it would otherwise. This means that for people with chronic kidney disease, lowering salt intake can help to keep the kidneys working well for longer.
This is partly because salt raises blood pressure and high blood pressure is very bad for kidneys. However, the kidney is the organ that removes salt from the body and a high salt intake seems likley to have a direct effect on kidney function.
If you have advanced chronic kidney disease (CKD) then your kidneys may find it difficult to get rid of the salt that you eat. If this salt accumulates then water will accumulate with it in your body. This causes oedema or swelling, especially of your ankles. It can also cause your blood pressure to rise.
If you have CKD, you may be given a diuretic (or ‘water tablet’) to help your kidneys to remove the salt from your body. By helping your kidneys to remove the salt, it helps to remove the water with it. As a result you may notice that you pass more urine than normal after taking the tablet. Commonly used diuretics are furosemide (previously called frusemide), bumetanide and bendorflumethazide (previously called bendrofluazide).
If your kidney is struggling to eliminate the salt that you are eating, then it makes sense to try to reduce the salt you are eating and so make it easier for your kidneys to do their job.
Read what Kidney Research UK says about salt here.