5. Potassium Restriction in Diet
Why are CKD patients advised to restrict potassium in diet?
Potassium is an important mineral in the body that is needed for the proper functioning of muscles and nerves and to keep the heart beat regular. Normally, the level of potassium in body is balanced by eating potassium containing foods and removal of excess potassium in the urine. Removal of excess potassium in the urine may be inadequate in a patient with chronic kidney disease and can lead to the accumulation of a high level of potassium in the blood (a condition known as hyperkalemia). The risk of hyperkalemia is less in patients undergoing peritoneal dialysis compared to those on hemodialysis. The risk differs in both groups because the process of dialysis is continuous in peritoneal dialysis while it is intermittent in hemodialysis.
High potassium levels can cause severe muscleweakness or an irregular eart rhythmthat can be dangerous. When potassium is very high, the eart can stop beating unexpectedly and cause sudden death. High otassium levels can be life threatening without noticeable manifestations r symptoms (and therefore it is known as a silent killer).
To avoid serious consequences of high potassium, CKD patients are dvised to restrict potassium in diet.
What is normal potassium level in blood? When is it onsidered high?
The normal serum potassium (level of potassium in blood) is 3.5 mEq/L to 5.0 mEq/L.
When the serum potassium is 5.0 to 6.0 mEq/L, dietary potassium needs to be limited.
When the serum potassium is greater than 6.0 mEq/L, active medical intervention is needed to reduce it.
A serum potassium greater than 7.0 mEq/L is life threatening and needs urgent treatment such as emergency dialysis.
Classification of food according to potassium content
To maintain proper control of potassium in blood, food intake must be modified as per the doctor’s advice. On the basis of potassium contents, oods are classified into three different groups (high, medium, and low otassium containing foods).
High potassium = More than 200 mg/ 100 gms of food
Medium potassium = 100 to 200 mg/ 100 gms of food
Low potassium = Less than 100 mg/ 100 gms of food
Foods with high potassium content
- Fruits: Fresh apricot, ripe banana, chico, fresh coconut, custard apple, gooseberry, guava, kiwi fruit, ripe mango, oranges, papaya, peach, pomegranate and plum
- Vegetables: Broccoli, cluster beans, coriander, drumstick, mushroom, raw papaya, potato, pumpkin, spinach, sweet potato, tomatoes and yam
- Dry fruits: Almond, cashew nut, dates, dry figs, raisins and walnut
- Cereals: wheat flour
- Legumes: Red and black beans and mung (monggo) beans
- Non-vegetarian food: Fish like anchovy and mackerel; shell fish like prawns, lobster and crabs; and beef
- Drinks: Coconut water, condensed milk, buffalo milk, cow milk, chocolate drinks, fresh fruit juices, soup, beer, wine and many aerated drinks
- Miscellaneous: Chocolate, chocolate cake, chocolate ice cream, Lona salt (salt substitute), potato chips and tomato sauce
Foods with Medium Potassium Content
- Fruits: ripe cherries, grapes, lychees, pear, sweet lime and watermelon
- Vegetables: Beet root, raw banana, bitter gourd, cabbage, carrot, celery, cauliflower, French beans, okra (ladies finger), raw mango, onion, radish, green peas, sweet corn and safflower leaves
- Cereals: Barley, general purpose flour, noodles made from wheat flour, rice flakes (pressed rice) and wheat vermicelli
- Legumes: red and black beans and mung (monggo) beans
- Non-vegetarian food: Liver
- Drinks: curd
Foods with Low Potassium Content
- Fruits: Apple, blackberries, lemon, pineapple and strawberries
- Vegetables: Bottle gourd, broad beans, capsicum, cucumber, garlic, lettuce, green peas, raw mango and pointed gourd
- Cereals: Rice, rava and wheat semolina
- Legumes: Green peas
- Non-vegetarian food: Beef, lamb, pork, chicken and egg
- Drinks: Coca-cola, coffee, lemonade, lime juice in water, and soda
- Miscellaneous: Cloves, dried ginger, honey, mint leaves, mustard, nutmeg, black pepper and vinegar
Practical Tips to Reduce Potassium in Food
- Take one fruit per day, preferably with low potassium.
- Take one cup of tea or coffee per day.
- Vegetables with potassium should be taken after reducing the amount of potassium (as mentioned below).
- Avoid coconut water, fruit juices and foods with high potassium contents (as listed above).
- Almost all food contains some potassium, so the key is to choose foods with a low potassium content when possible.
- Restriction of potassium is necessary not only for predialysis CKD patients, but is also necessary even after initiating dialysis.
How does one reduce potassium content in vegetables?
- Peel and cut vegetables into small pieces.
- Wash vegetables with lukewarm water and put them in a large pot.
- Fill the pot with hot water (the quantity of water must be four to five times the volume of vegetables) and soak the vegetables for at least one hour.
- After soaking the vegetables for 2 - 3 hours, rinse them three times with warm water.
- Subsequently boil the vegetables with extra water. Discard the water.
- Cook the boiled vegetables as desired.
- Although you can reduce the amount of potassium in vegetables, it is still preferable to avoid high potassium containing vegetables or take them in small quantities.
- As vitamins are lost in cooked vegetables, vitamin supplements should be taken as per the doctor’s advice.
Special tips for leaching potassium from potatoes
- Dicing, slicing or grating potatoes into smaller pieces is important. Maximizing the surface of the potatoes exposed to water by this method helps increase potassium loss from the potatoes.
- The temperature of the water used to either soak or boil the potatoes makes the difference.
- Using large amounts of water to soak or boil potatoes is helpful.