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:
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:
Reducing methionine in your diet
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.
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.
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