Diet ...tell me more

Increasing fluid in the diet

What should I drink? All liquids count toward your fluid targets. Some people prefer to avoid tea, coffee and alcohol as these can dehydrate you. However, it is best to drink anything in moderation as long as the bulk of its content is a fluid such as water, which does not dehydrate you.

Tips to help you increase your fluid intake:
  • Drink a large glass of water at specific times during the day e.g. when you get up in the morning, when you arrive at work, after using the toilet etc.
  • Enjoy a glass of fruit juice with your breakfast.
  • Keep a large bottle or mug of water at your desk and sip from it throughout the day.
  • Try drinking through a straw, it may help you drink more.
  • Drink one glass of water each hour on the hour.
  • When you have a craving for a snack, drink a glass of water, squash or a fizzy drink (choose diet if you are watching your weight) instead.
  • Add slices of lemon, lime or oranges to cool water. This gives it a pleasant flavour and helps to alkalinise your urine.
  • Drink two full glasses of fluid at each meal – one before and one after eating.
  • Carry a refillable water bottle everywhere – walking, shopping, driving, watching television, doing laundry, etc.
  • Flavour your water with squash.
  • Eat more fruits and vegetables as they contain a high amount of water.
  • Include liquid and moist foods in your diet e.g. soups, stew, jellies etc.
Fluid content of moist food:
  • 150g Pot yoghurt - 120ml
  • 100g Fromage frais - 80ml
  • 150g Rice pudding/ custard -  120ml
  • Porridge (medium size) - 130ml
  • 1 scoop ice cream - 60ml
  • 1 small ice lolly - 50ml
  • 1 large ice lolly - 130ml
  • 1 tablespoon sauce/ gravy - 20ml

Reducing your salt intake

It has been shown in some small studies that salt restriction reduces cystine excretion in both adults and children. The mechanism behind this is not known. (Goldfarb, Coe & Asplin, 2006). A high salt intake is directly associated with significant increase in renal calcium excretion and can therefore also increase the risk of calcium based stone formation, (Straub & Hautmann 2005). Cystinuria patients are at risk of forming calcium based stones so it is worth noting this.
Reducing salt intake has numerous other health benefits. It helps prevent raised blood pressure and reduces the risk of the following health problems:
Tips to lower your salt intake
  • Stop adding salt to your food during cooking.
  • Avoid adding salt to your meal at the table – taste it first and add other flavourings such as herbs, spices, mustard, pepper, lemon juice, garlic, and vinegar instead if you wish.
  • Cut down on the amount of salty ingredients used in cooking such as stock cubes, soy sauce, garlic salt or celery salt. Look out for low salt stock cubes or powders to use instead or make your own.
  • Avoid obviously salty foods such as crisps, nuts and salted biscuits.
  • Cook with fresh foods as often as possible rather than relying on ready made or processed foods.
  • Increase the amount of fruit and vegetables in your diet and use fresh or frozen vegetables rather than tinned vegetables.
  • Check food labels and try to choose brands that contain less salt.
  • Look out for reduced salt varieties of some processed food e.g. baked beans, pickles, ready meals.
  • Choose breakfast cereals that are low in salt or contain no added salt such as Shredded Wheat, Weetabix or porridge.
  • Avoid packet or tinned soups. Try homemade soup instead.
Reducing methionine in your diet

Reducing your intake of animal protein foods such as meat, fish and cheese will mean you have less methionine (the amino acid precursor to cystine) in your diet. Less methionine in the diet will mean there is less cystine being filtered and excreted via the kidney. A reduced methionine diet has been recommended for patients based on this premise. (Barbey et al. 2000; 2007). It is worth noting that even if all dietary amino acid intake is eliminated, cystine will still be produced in the body by normal metabolic activity (Mattoo & Goldfarb, 2008).

Protein is a very important nutrient in the body. One of its functions is growth and repair in the body so it is important that you eat enough to meet your body’s needs. When you decrease your intake of animal protein you should try to increase your intake of vegetable protein foods such as beans and pulses. Protein is also found in smaller amounts in other foods such as bread, potatoes and pasta.

The amount of protein you need depends on your weight. Your Dietitian can help you work out how much protein you need.

Alkalinisation of the Urine

Alkalinisation of the urine can help prevent the formation of cystine stones. The solubility of cystine in the urine is 250mg/L up to a pH level of 7.0, but solubility of cystine increases to 500mg/L or more with a pH level of 7.5 (Mattoo & Goldfarb, 2008). A urine pH of greater than 7.5 can predispose to the formation of calcium phosphate stones, therefore it is important to monitor urine pH level and try to maintain between 7- 7.5.

Drinking alkalinizing beverages, such as mineral water, rich in bicarbonate and low in sodium (1500mg bicarbonate/L, maximum 500mg sodium/L) and citrus juices may be helpful.

Reduction of animal protein, which is the major dietary source of protons, reduces renal proton excretion and increases urine pH. A reduction in animal protein intake often leads to an increase in fruit and vegetable consumption. Fruit and vegetables are high in organic anions which will help to alkalinise the urine by reducing renal proton excretion and increasing bicarbonate in the urine (Mattoo & Goldfarb 2008).

Why is a healthy weight important?

Overweight people are at a significant increased risk of stone formation. Urine pH is unfavourably low, in terms of crystallisation risk, in overweight patients (Straub & Hautmann, 2005). It has been found that people with a higher body mass index (BMI) have higher urinary excretions of uric acid, sodium, phosphate and ammonium (Siener R et al. 2004). Thus, overweight people have an increased risk of forming a variety of kidney stone types.

Overweight and obese people are at increased risk of the following conditions:-
  • Type 2 diabetes
  • Cardiovascular disease
  • Dyslipidaemia
  • Hypertension
  • Osteoarthritis
  • Breathlessness
  • Hyperuricaemia and gout
  • Certain cancers; including colon, kidney, prostate (men), postmenopausal breast and endometrial (Thomas 2007)
Why is eating enough fibre important?

A wide variety of high-fibre plant foods contain a compound called phytate. It has been demonstrated in experimental studies that patients with a low phytate intake had an increased risk of calcium oxalate stone formation (Straub and Hautmann 2005). As cystine stone formers are also at an increased risk of forming other stone types, it would be wise to ensure an adequate fibre intake.

Why is having enough calcium in my diet important?

As most of us know, calcium is important for bone health. Adequate calcium intake is also important in helping prevent formation of kidney stones. It has been found in two large studies that reduced calcium intake resulted in increased formation of calcium stones (Tiselius et al., 2002). As cystine stone formers can also develop calcium based stones it is important to ensure adequate calcium intake.

Reference List

Barbey, F., Joly, D., Rieu, P., Méjean, A., Daudon, M. and Jungers, P.(2000). Medical treatment of cystinuria: critical reappraisal of long term results. The Journal of Urology. 163(5), 1419-1423.

Goldfarb, D.S., Coe, F.L. and Asplin, J.R.(2006). Urinary cystine excretion and capacity in patients with cystinuria. Kidney International. 69, 1041-1047.

Kennedy, K.P., Bhatt, J.R. and MacDonagh, R.P.(2006). Dietary advice for patients with renal stones: are we practising evidence-based medicine? British Journal of Urology International. 97(5), 903-904.

Mattoo, A. and Goldfarb, D.S.(2008).Cystinuria. Seminars in Nephrology. 28(2), 181-191.

Pak, C.Y.C.(2008).Medical stone management: 35 years of advances. The Journal of Urology. 180(3), 813-819.

Parmar, M.S.(2004). Kidney Stones. British Medical Journal. 328, 1420-1424.

Siener, R., Glatz, S., Nicolay, C. and Hesse, A.(2004) The role of overweight and obesity in calcium oxalate stone formation. Obesity Research. 12(1), 106-113.

Straub, M. and Hautmann, R.E.(2005). Developments in stone prevention. Current Opinion in Urology. 15, 119-126.

Tiselius, H.G., Ackermann, D., Hess, B. and Boevé, E. (2002). Stone disease: diagnosis and medical management. European Urology. 41(5), 1 -11.
Thomas,B.(2007). Gout and Renal Stones. Manual of Dietetic Practice, Fourth Edition. Oxford: Blackwell Science ltd. pp 537-544.

Thomas,B.(2007). Obesity – general aspects. Manual of Dietetic Practice, Fourth Edition. Oxford: Blackwell Science ltd. pp 567-584.

Wasserstein, A.G.(2005). Nephrolithiasis. American Journal of Kidney Diseases. 45(2), 422-428. Salt & Health. Accessed March 2010. Biyani, C.S.(2007) Cystinuria. Accessed July 2008.
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