Diet and exercise for chronic kidney disease

The kidneys are involved in many different bodily processes. If they are no longer working properly, it causes an imbalance in your energy and protein metabolism, for instance. The levels of salts and fluids in the body are also affected. Advanced kidney disease may then cause serious effects such as weight loss, acidosis (a build-up of acid), and fluid retention in organs and tissue. Then at the latest there are number of diet rules that need to be followed.

Most people who have chronic kidney disease can drink as much as they like at first. But at an advanced stage of disease, the body flushes out less water. If you then also drink too much, the fluids can't leave your body fast enough. This results in edema (swelling due to fluid retention) and rising blood pressure levels. You can take medicine known as diuretics to reduce the amount of fluids retained in the body. You can then watch your body weight to check whether enough water is being lost.

If you ultimately need dialysis, then you need to only drink a certain level of fluids because dialysis can only flush out a limited amount.

Ideally, you should only drink as much fluids as the kidneys excrete in the form of urine – plus 0.5 liters per day in hemodialysis or 0.8 liters per day in peritoneal dialysis. This amount includes both drinks and liquid foods such as soups, yogurt and stewed fruit. You can use a special sheet to keep track of the amount of fluids you have been drinking.

To make sure you don't drink too much, it can help to use smaller glasses and cups, and to take medication with a meal instead of with an extra glass of water, if possible. You can suppress your thirst by chewing on a sour candy, a slice of lemon or sugar-free gum. Drinking slowly and avoiding dry indoor air can also help.

If you have chronic kidney disease and are also overweight, you can lower your risk of complications like heart attacks or strokes by losing weight.

But it is rare for people with advanced chronic kidney disease to be overweight – they are more likely to lose too much weight instead. To prevent being underweight, it is important to eat enough and to eat right. It is recommended that dialysis patients eat 30 to 40 kilocalories (kcal) per kilogram of normal weight. By “normal weight” we don't mean your current weight, but the weight that is considered to be normal for your height according to the body mass index (BMI) formula. This would be about 70 kg for a man who is 180 cm tall, for example. Based on that normal weight, the recommended amount of calories would be 2,100 to 2,800 kilocalories per day.

People who do not yet need to have dialysis should be careful to get the right amount of protein – not too much, but also not too little. Several studies suggest that in some people, a low-protein diet can delay the progression of chronic kidney disease. Having too little protein in the can be a problem too though, because it causes the muscles to lose protein. So experts don't recommend a strict low-protein diet for people with kidney disease.

According to current recommendations, people should get about 0.8 grams of protein in their daily diet for each kilogram of normal body weight. So if you weigh 75 kilograms, this would mean you would ideally get about 60 grams of protein in your diet. But you should also make sure that most of this protein is from plants. 100 grams of cooked legumes contain between seven and ten grams of protein, which is about the same as in nuts. Whole wheat foods contain between 3 and 6 g and starchy vegetables like potatoes or carrots have 2 to 4 g per 100 g. There is between 3 and 4 grams of protein per 100 grams in meat, eggs and cheese, and between 3 and 4 g in 100 ml milk or yogurt.

People who are on dialysis will need more protein, though. At least 1.1 grams of protein per kg of body weight is recommended for hemodialysis, and up to 1.5 grams is recommended for peritoneal dialysis. That is because a certain amount of protein is lost to the dialysis fluid through the peritoneum.

High blood pressure and too much protein in urine can make chronic kidney disease get worse faster. Studies have shown that a low-salt diet can reduce blood pressure as well as the loss of protein. Based on initial research, experts think that it can help delay or lower the risk of complications like kidney failure or heart attacks. But these results still need to be confirmed in long-term studies.

Salt also causes your body to "hold onto" too much fluid and makes you thirstier. So you should use less salt if you are not able to drink a lot.

Experts recommend less than 5 g of salt per day. As a basic guide, one slice of bread contains about 0.5 grams of salt, a hot dog sausage has about 2 grams in it and a slice of pizza has over 4 grams. Avoiding salty foods can be difficult, especially at first. But after two to three weeks, your sense of taste can get used to less salt. Some dishes can be made tastier by using herbs, onions, lemon, vinegar or other spices instead.

If you need dialysis, salt (sodium chloride) and other minerals can cause problems: Then it is more difficult for your body to regulate your potassium and phosphate levels. So if you are having dialysis, you should stop eating foods that contain a lot of these minerals. Examples of foods high in potassium and phosphate include bananas, dried fruits, potato chips, chocolate, French fries and processed cheese (spreads). Low-sodium or sodium-free salt substitutes should be used with caution: They have low amounts of sodium, but contain a lot of potassium.

It is highly questionable whether over-the-counter dietary (such as vitamin or mineral) supplements can help people with chronic kidney disease. Studies show that antioxidants such as vitamin E supplements can neither increase life expectancy in people with chronic kidney disease nor prevent complications like heart attacks or strokes. There is also no proof that these medications can slow down the progression of the disease or help in certain people (such as dialysis patients). This is true for fish oil and omega-3 fatty acid supplements, too. Dietary supplements with protein can have a positive effect on the proteins in your blood, but they do not have any influence on your weight. It is not clear whether they can increase life expectancy.

Getting exercise is good for you, even if you have chronic kidney disease. Regular exercise can help to lower your blood pressure, maintain your endurance and muscle tissue, and help you to feel better overall. The research has not shown that people with chronic kidney disease live longer if they do sports.

Experts recommend getting in 30 minutes of low-intensity exercise five times per week – especially if you also have high blood pressure. If you can't manage that, then it's best to make sure that you get as much exercise as you can in your everyday life, like taking the stairs instead of the elevator or walking places instead of driving. It can help to make physical activities a set part of your daily routine. It is even possible to exercise during a dialysis session – by pedaling on a specially designed bed exercise bike, for example.