As blood passes through the kidneys, it is "cleaned" - the body's waste products and excess fluid are removed. These waste products, along with the excess fluid, are then sent through the ureters to the bladder. Then they are passed out of the body as urine. Click here to view animation (courtesy of The Kidney Patient Guide)
Healthy kidneys also balance the chemicals in the blood, and produce hormones which control blood pressure and maintain healthy blood cells and bones.
What causes kidney failure?
There are a number of known causes of kidney failure but in quite a lot of people the cause is never found. The commonest causes are diabetes, high blood pressure and a painless inflammation of the kidneys called glomerulonephritis. There is a progressive loss of the filtering units (nephrons) in the kidney.
Other common causes are the inherited condition of cysts in the kidneys (polycystic kidney disease); repeated kidney infections or kidney infections (pyelonephritis) in childhood; and obstruction to the urine flow.
Common causes of kidney failure:
- Diabetes
- High blood pressure
- Glomerulonephritis
- Polycystic kidney disease
- Scarring from kidney infection in childhood
- Obstruction
What happens when the kidneys fail?
If the kidneys are damaged, they may carry on producing urine but become less efficient at removing waste products from the blood. Instead, the waste products continue to circulate and build up in the bloodstream. At the same time, without the hormones that a healthy kidney would produce, the bone marrow becomes less efficient at producing red cells, so anaemia develops.
For some patients, this may be a very gradual process. Over time, however, it can cause quite a wide range of symptoms. Not everyone will experience all the symptoms. Also, because it can be such a gradual process, some people don’t even realise the effect the symptoms are having until - with treatment - they begin to feel better.
Once the kidney problem has been diagnosed, regular blood tests will be required. Treatment with a variety of drugs may be needed, for example, to control blood pressure.
Common symptoms of kidney failure:
- Generally feeling ill
- Lacking interest in everyday activities; difficulty in concentrating or relaxing
- Tiredness and loss of energy
- Shortness of breath
- Altered taste sensation/appetite
- Increased night-time urine production
- Sickness and nausea
- Loss of libido/sex drive
- Itch
- Swelling of the legs
Eating Well for your Kidneys
This information is only intended for those patients in the early stages of kidney disease, generally managed by their GP. If you have been told to follow any dietary restrictions this information may not be suitable for you. Please seek advice from your doctor or dietitian instead.
I have been told I have kidney disease. What does this mean?
This means that your kidneys are not doing as good a job as they should be to help keep you healthy. Your kidneys normally remove waste products and extra fluid from your blood. These waste products and fluid come from the foods that you eat and liquids that you drink. If you have kidney disease, some of the waste products and extra fluid remain in your blood. Sometimes, early kidney disease may progress to more advanced kidney disease. If you follow your doctor's advice carefully, you may be able to slow down this process.
How can changes to my diet and lifestyle help my kidneys?
During the early stages of kidney disease, it is important that you try to eat a healthy, well balanced diet. Some lifestyle changes, such as taking more exercise, may also be helpful. Changes to your diet can help to control the build up of waste products and fluid in your blood, and decrease the workload of your kidneys. Your doctor may recommend a special diet, depending on the stage of your kidney disease. Your doctor may want you to see a dietitian, who has expert knowledge about diet. The main goal of this diet is to keep healthier for longer.
Achieving Good Nutrition
Eating a balanced diet is important for everybody, but particularly when you have kidney disease.
Tips for eating well:
- Enjoy your food
- Eat regular meals - do not skip breakfast!
- Aim to be a healthy weight
- Eat fruit and vegetables every day
- Base your meals around starchy foods (bread, cereals and potatoes)
- Eat less salt
A balanced diet:
A balanced diet contains a variety of foods from the 5 different food groups. This is important to make sure you get enough energy (calories) and protein from food, as well as essential vitamins and minerals.
The 5 food groups are:
1. Bread, cereals and potatoes
2. Fruit and vegetables
3. Meat, fish and alternatives
4. Milk and dairy foods
5. Fatty and sugary foods
Try to be a Healthy Weight
It is important that you maintain a healthy weight when you have kidney disease. What if I am losing weight? Sometimes having kidney disease can affect your appetite. If you have lost your appetite or you are rapidly losing weight then please highlight this to your doctor and ask to speak to a dietitian.
What if I am overweight?
Eating more calories than you use will result in weight gain. Even a small amount of weight loss will help to protect your heart and kidneys, help control your blood pressure and may prevent or help to control diabetes. There are lots of things you can do to control your weight, such as:
- Eat regular, planned meals and try not to snack on high energy foods between meals
- Eat fewer foods that are high in fat and sugar
- Choose lower fat cooking methods such as grilling, baking and boiling
- Eat plenty of fruit and vegetables
- Eat more filling foods such as bread, pasta and rice
- Shop from a list and avoid shopping when you're hungry
- Take regular exercise
A steady weight loss of about half to one kilogram (1-2lb) per week is the safest way to lose weight. If you need more help speak with your GP.
What is the Big Deal about Salt?
Most people in the UK eat too much salt. The average intake is double that recommended for a healthy diet. Everyone should cut down their salt intake to around 6g each day.
Why is too much salt bad for me?
A high salt intake is linked with high blood pressure and heart disease. It is therefore advisable that the whole family cuts down their salt intake. Some salt is naturally present in foods, whilst most salt comes from processed foods. The rest of the salt you eat comes from that added to your food at the table and during cooking.
To reduce the amount of salt you eat, try these suggestions:
1. Do not to add salt at the table: Remember, tomato ketchup, brown sauce and soy sauce are also very high in salt and should only be used in small amounts e.g. an individual sachet portion. Pepper, vinegar, herbs and spices can be used to add flavour to food.
Tip! Your taste buds will quickly adapt to using less salt on your food. You will find that after about a month food will start to taste much better.
2. Cook without salt: There are lots of ways to add flavour to your cooking without using salt. Ideas includeo Adding fresh or dried herbs such as basil, oregano, chives and tarragon to pasta dishes, meat, fish and vegetables. Marinating meat and fish in advance to give them more flavour e.g. use garlic, onions, lemon. Using garlic, ginger, chilli, lime, basil and oregano in stir fries and sauces. Using different types of onion, e.g. red, white, spring onions, shallots.
Tip! Try not to add salt automatically when you are cooking or about to eat. People often only use salt out of habit.
3. Cut down on manufactured and processed foods: Try using fresh or frozen meat, fish and vegetables, rather than pre-prepared dishes or ready meals whenever possible. If buying tinned vegetables, choose those labelled 'no added salt' or 'reduced salt' and boil in fresh water.
Warning: Do not use salt substitutes e.g. Losalt, as they contain potassium chloride. These products are not suitable for people with kidney problems.
Exercise for Everybody
Regular exercise is beneficial to people with kidney disease, regardless of age or physical ability. It may be a daunting thought but regular exercise has lots of benefits, such as general good health and well-being, improving blood pressure, keeping your heart and muscles strong and healthy, and helping to control your weight.
So, what is stopping you?
Ideally, exercise should be integrated into your daily routine and with time will become easy and enjoyable. Try walking further instead of taking the bus, or climb the stairs instead of using the lift at work. Try to involve all the family.
What is the best exercise to choose?
Regular, low-intensity exercise within your own capabilities is best. If it has been a while since you have been active, build up slowly from 5 minutes to 30 minutes at a time. Try to aim for 3 to 5 sessions of activity per week.
Try endurance exercise such as brisk walking, cycling, dancing or swimming. Exercises which are good for improving flexibility and mobility are Bowls, Pilates, T'ai Chi or Yoga.
Tip! Remember, you do not have to push yourself too hard to see the benefits of exercise - it just has to be regular.
Alcohol in Moderation
If you normally drink alcohol, this is something that you probably want to know about. Alcohol in moderation is the key for most people.
What is the general recommended alcohol intake?
Up to 3-4 units a day for men
Up to 2-3 units a day for women and older adults
'One unit' is the same as ½ pint of ordinary beer or lager, 1 small (125 ml) glass of wine or 1 (25cl) pub measure of spirit. Try to spread your drinking throughout the week, and have at least 1-2 alcohol free days per week.
Are there any limits on the type of alcohol I can drink?
Only if you have been advised to follow a low potassium diet or limit your fluid intake. Certain types of alcohol contain more potassium than others. If you are following a potassium restriction, ask your dietitian for more details about the types and amounts of alcohol you can have per week. Alcohol contains a lot of energy, and no vitamins or minerals. An excessive alcohol intake might result in unnecessary weight gain.
Tip! Don't save up all of your units for one day i.e. Do not drink more than your daily limit in one day.
Finally... if you are taking medication and are unsure as to whether you can drink alcohol - always check with your doctor.
Diabetes
If you have kidney problems and diabetes, the information here still applies to you!
Even If you are told you may need to make alterations to your diet to help your kidneys, a healthy diet for your diabetes is still very important.
It is also important that you follow the advice given by the doctors and the diabetes nurses to help control your blood sugar levels.
Rough Guide to Protein
Protein from food is needed for growth, repair of muscle and tissues, and fighting infection. Healthy kidneys get rid of the waste product of protein - urea - in the urine. When your kidneys are not working well, the level of urea in the blood can rise and this may make you feel unwell.
How can I eat the right amount of protein?
It is just as important to make sure you do not eat too much or too little protein, as your muscles and body tissues will break down to provide the protein your body needs. This may also cause you to feel unwell.
Which foods contain Protein?
Meat: beef, lamb, pork
Poultry: chicken, turkey
Fish: all types
Pulses: lentils, beans, chickpeas
Vegetable Protein: Quorn, Soya, Tofu
As a guide these should be eaten twice a day e.g. at both main meals
Milk: About ¾ pint or 400ml each day
Eggs: 3-4 each week unless you are a vegetarian
Cheese, Yoghurt, Milk Pudding: Twice a week
It is not necessary to follow a low protein diet!
The following sections are for those who are attending specialist kidney clinics -
Your blood phosphate and potassium levels will be checked regularly.
The normal blood levels for phosphate are 0.7 - 1.4mmol/l.
The normal blood levels for potassium are 3.6 - 5.3mmol/l.
If your levels are higher than normal then you may need to be referred to a specialist renal dietitian.
A Word About Phosphate
Phosphate is a mineral that helps to keep your bones and teeth healthy. When your kidneys are not working efficiently the level of phosphate in your blood can begin to rise. In the short term a high phosphate level can cause itchy skin and red eyes.
Where does phosphate come from?
Phosphate is present in many foods in particular
- Hard cheeses, cheese spread and processed cheese
- Nuts
- Processed meats
- Offal
- Oily fish e.g.; mackerel, sardines
- Shellfish e.g.; prawns, scampi
Do I need to follow a strict low phosphate diet?
No. If you eat the foods in this list regularly though then it would be a good idea to try to eat them less often. Everybody with kidney disease will benefit from cutting down on high phosphate foods. If you need to follow a low phosphate diet, your doctor should refer you to a renal dietitian who can give you specific advice regarding your diet.
What if my doctor has asked me to take phosphate binders?
To help control the phosphate in your blood, you may need to take medicines called phosphate binders. Your doctor will tell you if you need them. The renal dietitian can advise you about the best times to take these medicines.
A Few Words about Potassium
Potassium is a mineral that keeps your heartbeat regular and your muscles working. Your kidneys normally remove extra potassium from your blood, but if they do not work well potassium levels in your blood can rise.
Where does potassium come from?
Potassium is found in certain foods but there are many reasons for a high blood potassium level e.g. medications and uncontrolled sugar levels if you are diabetic. Ideally these should be investigated first before you need to restrict the amount of potassium from your diet.
You only need to cut down on the potassium in your diet if a doctor or dietitian tells you to.
What should I do if I am told I need to follow a low potassium diet?
Your doctor should refer you to see a dietitian who can advise you about a low potassium diet.
Where Can I Find More Information?
The Internet Remember that the quality of the information on the internet is not always good, so be careful not to follow everything you read. If you are not sure about something, or want more information about useful websites, please ask.
The Library Many good books have been published for renal patients, their families and carers. These cover a wide variety of topics, including diet. There are also renal recipe books available.
A Dietitian Renal dietitians, who work mainly with people who have kidney disease, can offer more detailed advice on any of the topics mentioned in this section. They can tailor this advice to your personal needs, and take into account cultural or religious requirements. Alternatively, they can answer any questions you may have. A doctors referral is needed if you would like to see a dietitian.
And finally...
We hope the information in this section has been useful, and has given you some food for thought. Remember, please ask your doctor or nurse to refer you to a dietitian if you have any concerns about your diet.
Used with permission of the Renal Dietitians at Derby and taken from the CKD Forum Website.
Designed by the Renal Dietitians at Derby Hospitals NHS Foundation Trust. August 2006
Endorsed by the Renal Nutrition Group of the British Dietetic Association