A The kidneys remove waste from the blood via the urine; they regulate the levels of water and different minerals needed by the body, and they also produce hormones that control other bodily functions such as blood pressure.

Kidney failure comes in two forms. Acute kidney failure happens when the kidneys fail suddenly. They can return to normal functioning after a while, although dialysis may be needed until they begin to work again. Your friend, however, has chronic kidney failure, or chronic renal insufficiency, a condition that is irreversible. Indeed, if the efficiency of her kidneys is as poor as you state, she has endstage renal disease (ESRD) and will most definitely require dialysis to stay alive. Eventually, she may even need a kidney transplant.

Sometimes, it is not possible to get to the bottom of why a kidney is failing. Chronic cases can be brought on by diabetes, high blood pressure, kidney stones or a painless inflammation of the kidneys called glomerulonephritis. Case reports have also attributed incidents of acute kidney failure to the use of painkilling drugs such as aspirin, ibuprofen and naproxen. However, these patients often had other risk factors, such as systemic lupus erythematosus, advanced age or a chronic kidney condition, or had been bingeing on alcohol (PROOF!, vol 3 no 2, Q&A).

Acute cases can also be brought on by shock, usually as a result of a sudden blood loss or a heart attack, or by the sudden blocking of the ureters, bladder or urethra, often by kidney stones. Tell-tale symptoms can include poor urination, loss of appetite, abnormal sleep patterns or drowsiness.

Chronic cases can be brought on by recurrent inflammation (high blood pressure, kidney stones or glomerulonephritis, as mentioned above). Inflammation can also be caused by cadmium, although the most common cause is frequent use of aspirin and other similar painkillers.

The kidneys can repair themselves - but only in acute cases - and this also depends on the age and general health of the patient. Kidney failure is treated by a combination of methods, including diet, medication and possibly dialysis, according to the type of disease and severity.

Now that your friend is on dialysis, she should certainly continue with her good diet. If she’s not already doing so, this should include essential fatty acids, which may help to protect the kidneys. In cases of kidney disease, a dose of 12 g daily has been shown to retard the rate of kidney function decline (N Engl J Med, 1994; 331: 1194-9). Although not yet proved conclusively, lowering protein intake may also be of some benefit (N Engl J Med, 1994; 330: 877-84).

Salt increases thirst, making it more difficult for patients to restrict their fluid intake. Sodium is, of course, an essential nutrient, but doctors are still a long way from finding the healthy middle ground between consuming too much and too little (Am J Hypertens, 2001; 14: 653-9). If she doesn’t want to give up salt, she could try replacing it with a low-sodium alternative (WDDTY, vol 5 no 7, News).

Potassium is a mineral that, among other things, works in conjunction with sodium to keep water levels in the body consistent; the kidneys would normally remove any excess. Too much potassium is bad for the heart but, as you can’t taste potassium like you can salt, its intake is more difficult to control and it isn’t listed on food labels. High potassium levels are found in nuts, avocados, potatoes, oranges, peaches, apricots and anything dried, such as fruits, beans and lentils. Low potassium foods include grapes, tangerines, tinned pears and plums, asparagus, green beans, corn, cauliflower, cucumbers, water chestnuts and squash. Juices such as apple, cranberry, lemonade, grape and fruit-flavoured drinks are also fine.

Protein also plays an important role in the diet of any kidney patient. Low levels can lead to fluid retention and a reduced capacity of the body to fight off infection.

Finally, your friend must keep her blood pressure in check with regular exercise; deal promptly with any urinary tract infections as, left untreated, these can spread to the kidney; limit her exposure to toxic metals; and avoid unnecessary use of over-the-counter medicines, especially aspirin and other painkillers.

She may also wish to support her healthful regimen with homoeopathy.