How to prevent kidney stones recurring
Kidney stones affect around 10% of the population at some time in their lives. Data from the US shows that about 12% of men and 6% of women will get it at some stage in their life(1). This figure has been increasing over the last generation or two, presumably due to changes in diet and lifestyle that make stone formation more likely. White caucasian people are at increased risk, especially between ages 20-50. Once you’ve had a stone you are quite likely to develop another one.
There are various types of stone, and the best treatment depends on which type you have. The most common are calcium stones, either calcium oxalate or calcium phosphate. Stones made of uric acid are also fairly commonplace.
Kidney stones can cause serious complications if left untreated. Blockage of the kidney ducts can lead to dangerous infections and ultimately kidney failure.
- Caffeine has been reported to increase risk according to the Journal of Urology 2004. Caffeine is thought to bring about changes in the urine that allows for quicker precipitation out of solution of the chemicals that form stones. However there are plenty of studies that link tea and coffee consumption with lower risk of kidney stones.
- High doses of supplemental vitamin C may lead to increased risk of stone formation as some calcium oxalate stones are formed from vitamin C breakdown products.
- Alcohol impairs vitamin A status and as we see below this could lead to increased risk due to imbalance of fat soluble vitamins.
- Low carb or ketogenic diets result in increased levels of uric acid in the urine. Uric acid can crystallise and form the seeds for subsequent growth of a kidney stone. Increased acidity in the blood and urine enhances this problem(2).
- An imbalance of fat soluble vitamins could lead to kidney stone formation. A 1980 study on Israeli lifeguards with average blood levels of vitamin D of 60ng/ml showed a 20 fold increase in the rate of kidney stone formation(4).
- Illness and infection can assist stone formation by preventing vitamin C being recycled properly. This can lead to the production of oxalates which need to be removed by the kidneys.
- Urine pH can make it easier for stones to form. A more acidic urine is associated with uric acid stones, while a more alkaline urine is associated with calcium type stones.
Wrongly identified risk factors
- High protein diets have been associated previously with kidney stones, but there is actually not any good evidence for this currently. While excess protein in the diet does raise urinary calcium and uric acid, which are used to form stones, the increase has not been linked with kidney stones in studies(3). It is more likely that an issue only exists for those who have already got a pre-existing problem with their kidneys.
- Salt has been identified as leading to stone formation as it increases urinary excretion of calcium. However, increased consumption of calcium is thought not to be a problem. There is a lack of evidence behind the claim that salt is a problem and I remain to be convinced. Most studies criticisng have included salt with other dietary measures to reduce stone incidence.
- Tea and coffee contain water and the presence of water flowing through the kidney reduces risk of stone formation, by keeping problem chemicals in solution more effectively.
- Foods that contain calcium such as dairy, sardines and green leafy vegetables can help reduce the incidence of the most common type of kidney stone, namely calcium oxalate stones. Calcium binds to oxalate in the gut, so preventing its entry into the bloodstream.
- Foods containing vitamin B6 and magnesium may also help reduce risk of kidney stones. Vitamin B6 reduces oxalate in the urine and magnesium helps convert oxalate into other non stone-forming chemicals.
- The mineral, potassium, found in many fruits and vegetables is also associated with lower kidney stone risk. It is possible to take potassium citrate supplements also, which inhibit oxalate stones.
Supplementation is in my view only worthwhile if you already know you have kidney stones or are at high risk for kidney stones. Single nutrient supplements can have unintended consequences and should only be taken when there is a known reason for taking them. As such it may be worth supplementing magnesium at 300mg per day and vitamin B6 at 30mg/day. There are various studies that have shown these measure to be quite effective in reducing the risk of kidney stone formation.
Balance your fat soluble vitamins
Vitamins A, D and K2 are best balanced out as they together determine where calcium gets deposited in the body.
Calcium is best deposited in our bones and teeth and worst deposited on kidney stones or the inside of arteries. Some studies have suggested that excess vitamin D is associated with increased kidney stone risk. This is logical if you think that vitamin D increases absorption of calcium from the gut. How that calcium gets used in the body is partly determined by vitamin K2 status. The more vitamin K2 the more the calcium is deposited in bones and teeth.
One well-known study found that beach lifeguards seem to be at increased risk due to sun exposure causing higher blood levels of vitamin D(4). Both vitamin A (liver, eggs, dairy and oily fish) and vitamin K2 (dairy) should balance out this risk.
Citric acid from citrus fruits such as lemon and oranges binds to calcium in the urine. It also makes the urine less acidic which slows stone development. You will find that medics sometimes offer potassium citrate pills, which effectively do the same job.
Some conventional therapies may help, but the use of CT scans to monitor stones has been associated with a rise in kidney cancer cases.
Shock Wave treatment - lithotripsy
Shock waves can be used to break up stones if they are not too big (less than 2cm in diameter). X-rays and pressure waves are used to break stones into smaller fragments that can then be passed in the urine without any pain. Pregnant women, people with bleeding disorders and the morbidly obese may not be suitable candidates for this type of treatment.
Surgery to remove kidney stones can be used.
An minor outpatient procedure can be used to remove stones if they are below as opposed to above the bladder. It is sometimes used in conjunction with laser fragmentation of the stone.
There are a number of medicines that are used to help dissolve stones.
1) http://perfecthealthdiet.com/category/disease/kidney-stones/ dangers of a ketogenic diet.
2) http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1262767/ high protein diets and kidney stones.
3) http://ajcn.nutrition.org/content/69/5/842.full vitamin D and stone risk.
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About Robin Dowswell
Robin Dowswell is a Nutritional Therapist working just outside Milton Keynes in Buckinghamshire. He specialises in sports nutrition, as well as having a keen interest in using diet as a powerful tool to enjoy improved health.