Drinking enough fluid is the most important means of preventing stone formation which will reduce your risk of stone formation by almost one third. Not drinking enough fluid causes your urine to become concentrated and makes stones more likely to form. Aim to drink two to three litres of fluid each day (water, squash, or fizzy drinks). You should aim to keep your urine colourless throughout the day. This equates to a urine output of at least two litres per day. In patients with cystine stones, however, an output of 3.5 litres per day is required.

Tea, coffee and milk can be consumed in moderation but the majority of your fluid intake should be as above. In addition, it is helpful to try and drink one or two glasses of water on rising in the morning.

Yes. A high intake of animal protein appears to increase the risk of stone formation. Avoid large portions of meat, fish, eggs, cheese and milk. You can replace protein with starchy foods (rotis, bread, aloo, fruit & vegetables) to fill you up. Reducing your protein intake also increases the amount of citrate you excrete in your urine; citrate is a known inhibitor of stone formation.

Yes. A high salt intake can contribute to calcium stone formation. Do not add salt to your food at the table but use pepper, herbs, spices or vinegar as alternative flavourings. You can add a small amount of salt during cooking. Foods which contain less than 0.4g (40mg) of sodium per serving are low-salt choices and you should aim to keep your salt intake down to these levels. Avoid high-salt, tinned, packet and processed foods (soups, salted crisps, nuts, tinned meats, meat paste, smoked fish and fish paste). Keep the total salt intake to less than 5 gm/day

You need to avoid oxalate-rich foods to reduce the amount of oxalate in your urine.

The following foods are high in oxalate:

· tea (more than two to three cups per day);

· chocolate;

· nuts & peanut butter;

· cocoa & carob;

· strawberries;

· rhubarb;

· celery, spinach & beetroot; and

· parsley.

It is not necessary to exclude oxalate-rich foods completely but simply to eat them in small amounts.

No. Severe calcium restriction can actually increase the risk of stone formation because it will result in high levels of oxalate in your urine. If you follow the recommendations above for milk, cheese and eggs, no further action is needed.

The calcium you drink in the water cannot cause kidneys stones and there is no need to restrict your intake of tap water, drink mineral water or purchase a water softener.

Most vitamins are harmless but do not take Vitamin D preparations, including fish oils and multivitamin preparations, because they increase calcium absorption. Avoid Vitamin C supplements because they increase the excretion of oxalate in your urine.

A normal calcium, low-salt, low-protein, diet can reduce your risk of stone formation by a half. Keeping your urine colorless may reduce the risk by a further one third.