Potassium exchange list and leaching of vegetables
Potassium exchanges group foods as low, medium or high potassium per portion so a kidney patient stays within a daily limit; leaching removes part of vegetable potassium.
Aim and principles
Aim: To classify foods by potassium content, demonstrate leaching of vegetables, and plan a day's menu within a potassium limit for a patient with chronic kidney disease. Principles: Potassium is needed for nerve and muscle function, but failing kidneys cannot excrete it. A serum potassium above the normal 3.5-5.0 mmol/L (hyperkalaemia) can cause dangerous heart rhythm problems, so patients with advanced CKD, scanty urine or certain medicines may need a potassium-restricted diet, often about 2000 mg (about 51 mEq) a day, adjusted to blood results. A potassium exchange list groups fruits, vegetables and other foods as low (below 150 mg), medium (150-250 mg) or high (above 250 mg) potassium per portion, so the patient can choose freely within a daily number of portions. Most potassium in Indian diets comes from vegetables, fruits, dals, milk and coconut water; rice, sago, cornflour, sugar and oil contain very little. Leaching (peeling, cutting small, soaking, then boiling in plenty of water that is thrown away) draws potassium out of vegetables; it lowers but does not remove potassium, and it also washes out some water-soluble vitamins. Salt substitutes contain potassium chloride and must be avoided. Potassium values differ between food tables (for example, IFCT 2017 gives ash gourd about 370 mg and French beans about 320 mg per 100 g, though many renal diet sheets list them lower), so the lists are a guide; the blood report decides the limit.
Nutrient prescription: Mrs. K, 60 y, 160 cm, 55 kg, CKD stage 4, serum potassium 5.8 mmol/L
| Nutrient | Prescription | Basis and source |
|---|---|---|
| Ideal body weight | 54 kg | (160 − 100) × 0.9 |
| Energy | About 1600 kcal | 30 kcal/kg × 54 = 1620 (KDOQI 2020: 25-35 kcal/kg) |
| Protein | About 32 g | 0.6 g/kg × 54 = 32.4 (KDOQI 2020) |
| Potassium | About 2000 mg (about 51 mEq) | Common working limit (KDOQI 2020 gives no fixed figure); 2000 ÷ 39 = 51.3; adjusted to serum potassium |
| Portions planned | Fruit: 1 low + 1 medium; vegetables: 2 leached low-potassium portions and a little tomato; milk 200 mL; moong dal 15 g | Choices from the potassium exchange list |
| Fluid | Previous day's urine + 500 mL | Scanty urine in advanced CKD |
Potassium exchange list (per portion, approximate)
| Food group | Low (below 150 mg) | Medium (150-250 mg) | High (above 250 mg): avoid or limit |
|---|---|---|---|
| Fruits (100 g edible) | Apple, pear, pineapple, watermelon | Papaya, grapes, mango, pomegranate, orange | Banana, guava, jackfruit, a glass of sweet lime or orange juice, a glass of tender coconut water, dates, raisins and other dried fruits |
| Vegetables (100 g raw) | Bottle gourd, ridge gourd, cucumber, onion | Cabbage, capsicum, brinjal, tomato, peas | Potato, sweet potato, yam, colocasia, drumstick, spinach, amaranth, carrot, beetroot, pumpkin, lady's finger, cauliflower, mushroom |
| Other foods | Rice, rava, sago, cornflour, sugar, oil, egg white | Milk or curd (100 mL); atta (50 g) | Dals and whole grams (30 g), nuts, milk powder, chocolate, instant coffee powder, tomato puree and ketchup, salt substitutes |
How to leach vegetables
Use for medium- and high-potassium vegetables, and for low-potassium ones when the limit is tight.
- 1Peel the vegetable and cut it into small, thin pieces (about 3 mm).more surface lets more potassium out
- 2Rinse the pieces in warm water.
- 3★Soak in warm, unsalted water, about 10 times the volume of the vegetable, for at least 2 hours.if soaking longer, change the water every 4 hours
- 4Rinse again in warm water.
- 5★Boil in fresh water, about 5 times the volume of the vegetable, and throw this water away.
- 6Cook the vegetable as poriyal or curry. Never use the soaking or boiling water for rasam, sambar or soup.
★ one-way, controls the pace
Sample one-day menu with potassium (Mrs. K)
| Time | Menu (approx. raw amount) | Approx. potassium (mg) |
|---|---|---|
| 6.00 am | Tea: toned milk 100 mL, sugar 10 g | 190 (milk 150, tea 40) |
| 8.00 am | Rice rava upma: rice rava 50 g, leached vegetables 30 g, oil 8 g | 82 (rice 58, vegetables 24) |
| 10.30 am | Apple (low potassium) 100 g | 110 |
| 1.00 pm | Rice 60 g; thin moong dal 15 g with tomato 30 g; leached bottle-gourd poriyal 100 g, oil 7 g | 386 (rice 69, dal 165, tomato 72, vegetables 80) |
| 4.00 pm | Sago payasam: sago 30 g, toned milk 50 mL, sugar 20 g, ghee 5 g | 78 |
| 8.00 pm | Phulka (1): atta 25 g; soft rice 30 g; egg-white curry: 1 egg white, leached vegetables 70 g, oil 8 g | 236 (atta 90, rice 35, egg white 55, vegetables 56) |
| 9.30 pm | Cornflour custard with sago: cornflour 20 g, sago 30 g, toned milk 50 mL, sugar 15 g; papaya (medium potassium) 100 g | 259 (custard 79, papaya 180) |
| Total | 1341 mg, about 34 mEq |
Worked calculation: Mrs. K's potassium budget
Mrs. K, 60 years, 160 cm, 55 kg, has CKD stage 4 (not on dialysis) and a serum potassium of 5.8 mmol/L. Find her IBW, energy and protein, total the potassium in the day's menu, convert it to mEq, and show what careless swaps would do.
- IBW = (160 − 100) × 0.9 = 54 kg.
- Energy = 54 × 30 = 1620, about 1600 kcal; protein = 54 × 0.6 = 32.4, about 32 g (KDOQI 2020).
- Potassium limit = 2000 mg; 2000 ÷ 39 = 51.3, about 51 mEq.
- Approximate potassium values used (mg): rice 115 and atta 360 per 100 g; moong dal 1100 per 100 g; toned milk 150 per 100 mL; tea decoction 40 per cup; egg white 55 each; apple 110, papaya 180 and tomato 240 per 100 g; low-potassium vegetables about 80 per 100 g after leaching (estimate, about 150 raw); sago, cornflour, sugar and oil almost nil.
- Potassium by meal = 190 + 82 + 110 + 386 + 78 + 236 + 259 = 1341 mg.
- In mEq: 1341 ÷ 39 = 34.4 mEq, well inside the 51 mEq limit, so one more medium-potassium portion could be added.
- Careless day: banana instead of apple (+250 mg), tender coconut water 200 mL instead of papaya (+320 mg) and vegetables not leached (+140 mg): 1341 + 250 + 320 + 140 = 2051 mg, about 53 mEq, over the limit.
- Energy and protein of the same menu (approximate values from Indian food composition tables, as in the other diets):
- Cereals (rice 140 g, sago 60 g, atta 25 g, cornflour/custard powder 20 g): 857.0 kcal, 14.0 g protein.
- Pulses (moong dal 15 g): 48.8 kcal, 3.6 g protein.
- Milk and milk products (toned milk 200 mL): 120.0 kcal, 6.0 g protein.
- Egg white (1 egg white): 17.0 kcal, 3.5 g protein.
- Vegetables (mixed vegetables 230 g): 69.0 kcal, 3.5 g protein.
- Fruits (apple 100 g, papaya 100 g): 95.0 kcal, 0.8 g protein.
- Oil and ghee (oil/ghee 28 g): 252.0 kcal.
- Sugar (sugar 45 g): 180.0 kcal.
- Energy = 857.0 + 48.8 + 120.0 + 17.0 + 69.0 + 95.0 + 252.0 + 180.0 = 1638.8 kcal.
- Protein = 14.0 + 3.6 + 6.0 + 3.5 + 3.5 + 0.8 = 31.4 g.
- Compare: energy 1638.8 ÷ 1600 × 100 = 102%; protein 31.4 ÷ 32 × 100 = 98%. All values are approximate; potassium values vary between food tables.
IBW 54 kg; about 1600 kcal, 32 g protein and 2000 mg (51 mEq) potassium prescribed. The menu gives about 1341 mg potassium (34 mEq), 1639 kcal and 31 g protein; careless swaps would push potassium to about 2051 mg.
Preparation and serving tips, and result
- Leaching lowers potassium but does not remove it all: still count leached vegetables as portions.
- Leaching also washes out vitamin C and some B vitamins; the doctor may advise a supplement.
- Read labels: 'low-sodium salt' and salt substitutes contain potassium chloride.
- Avoid tender coconut water, fruit juices and dried fruits, which pack a lot of potassium into a small amount.
- Weigh dal and milk; they are the biggest potassium sources after fruits and vegetables.
- Result: The day's menu gives about 1341 mg potassium (34 mEq), within Mrs. K's 2000 mg (51 mEq) limit, with about 1639 kcal and 31 g protein.
In the diet kitchen, renal vegetables are leached first thing in the morning in a separate labelled vessel, and the soaking water is thrown away, never used for rasam. The potassium exchange sheet lets the cook change fruits and vegetables daily while keeping each patient within the limit.
Short answer: “Convert 2000 mg potassium into mEq.” 1 mEq potassium = 39 mg, so 2000 ÷ 39 = 51.3, about 51 mEq.
Short answer: “Name four high-potassium foods to avoid in hyperkalaemia.” Banana, tender coconut water, potato, drumstick, spinach, dried fruits, large dal portions, salt substitutes (any four).
Structured question: “Describe leaching of vegetables and its importance in renal diets.” Peel, cut small, rinse, soak in warm water (about 10 times the volume) for at least 2 hours, changing it every 4 hours if longer, rinse, boil in fresh water (about 5 times the volume), discard the water, then cook. It lowers potassium so CKD patients can eat vegetables within their limit; it does not remove all potassium and also removes water-soluble vitamins.
Big four high-potassium foods: Banana, Coconut water, Potato, Greens. To leach: peel, dice, soak, boil, throw.