How to Reduce Risk of Kidney Stones
Kidney stones, known as renal calculus, are solid crystals stones salts of deitary minerals formed in the kidneys. The kidneys -- humans have two of them -- are organs that filters and remove wastes in the form or urine.
Many times kidney stones passes out of the body along with the urine without any major problem. However, sometimes they are large and can not pass easily causing extreme pain. Sometimes they obstruct the drainage system causing water and urine to be backed up inside the kidney. This is known as hydronephrosis and can cause damage and atrophy of the kidney.
When kidney stones obstruct or are unable to pass, they causes extreme abdominal pain known as renal colic -- colic meaning that the pain comes in waves. Additional symptoms may include nausea, vomiting, fever, and blood in urine. Medical attention is needed to provide drugs for pain management and/or techniques (such as extracorporeal shock wave lithotripsy or surgery) to remove the stones that do not expel by themselves.
Each year, there are 3 million doctor's visits for kidney stones treatment. Half a million people per year go to emergency room for problems with kidney stones. And the numbers have been increasing over the years.
Factor Affecting Kidney Stones
Factors that affect risk of kidney stones include heredity, environment, weight, diet, and fluid intake.
People who have had kidney stones are more prone to get them again. Hence, it is worthwhile to learn how diet may affect the risk of kidney stones. For certain susceptible people, certain foods may promote stone formation. Because stones are formed due to many different reasons, it is necessary to know what caused your particular stone before it can be determine what dietary measures to take in order to prevent recurrence.
To determine what caused the stone, it is important to know what type of stone you have. The stone or stone fragments can be analysed. To collect stone samples, doctors may ask you to urinate into a jar. Then pour the urine through a filter to collect any fragments so that you can accumulate the fragments in the jar for analysis.
In addition, they may also ask to collect a 24 hour urine sample. This checks for many different elements of the urine that was collected in a 24 hour period to see if there is any mineral or systemic imbalance in your system that might be causing stones. After the analysis, the doctor may have more specific recommendations in terms of diet to correct any imbalances.
Hence, dietary recommendations are particular to an individual and the type of stone. The below dietary information is general information that may or may not apply to your particular situation. So you may not want to make any drastic dietary changes without consulting with your doctor. Often the type of foods mentioned below that may cause stone in one person can be a very healthy food to eat in general.
Types of Kidney Stones
There are four major types of kidney stones:
- Calcium oxalate stone -- These are the most common representing 80% of the cases in the United States. They consists of calcium and oxalate and tend to form when urine is acidic (low pH level). This can also occur due to genetic condition of hyperoxaluria that causes the body to produce too much oxalate. They may also form in people with chronic inflammation of the bowel.
- Calcium phosphate stones -- These consists of calcium and phosphate and tend to form when the urine is alkaline (high pH level).
- Uric acid stones -- These tend to be formed when urine is persistently acidic which can be a result of a diet with excessive protein or prurine.
- Struvite stones -- These are caused by infections in the kidney. Hence a diet does not have much effect on the risk of these stones, expect perhaps a diet that is more preventative against infections.
- Cystine stones -- These result from a genetic disorder known as cystinuria that causes the amino acid cystine to leaks through the kidneys into the urine.
Fluid Intake to Reduce Risk of Kidney Stones
Sufficient water intake is one of the most important dietary factors in reducing risk of kidney stones. Not having enough fluids and losing too much fluid can increase risk of stones.
How much fluid you need to drink vary from individual to individual. It depends on your activity level as well as amount of fluid lost in perspiration.
In general, one should drink enough fluid so that you produce two quarts of urine a day. Having enough water passing through the kidneys dilute the minerals that form the stones. Note that fluid consumption can include drinking beverages as well as eating foods with high fluid content.
Your urine should be clear or mild yellow. If it is dark yellow, you are not drinking enough fluids. If you have just taken B vitamins however, your urine may be artificially bright yellow due to the excretion of the water soluable B vitamins in your urine.
Water is the best fluid to drink. It dilutes the minerals content in the urine and is helpful in reducing risk of all types of stones (except that it may not have much effect on struvite stones). Because water is of neutral pH, it balances any urine that is either too acidic or too alkaline.
Citrus Drinks May Help Prevent Calcium Oxalate Stones
Citrus drinks (such as lemonade and orange juice) are alkalizing and may be helpful in preventing calcium oxalate stones and uric acid stones. However, they might be harmful for people who form calcium phosphate stones.
Although lemons and oranges are acidic, after it has gone through your digestion process and metabolized, it causes urine to be more alkaline. This balances the excessive urine acidity associated with oxalate stones and uric acid stones. Hence lemon and oranges are alkalizing foods, even though they are acidity in and of themselves.
Calcium and Stone Formation
A condition known as hypercalciuria results in excessive urinary calcium excretion. This occurs in 5% to 10% of the population and may account for a large portion of the people with kidney stones.
Calcium-based antacids, certain diuretics, water pills, and calcium supplements may increase the risk of forming kidney stones by increasing the amount of calcium in the urine. Healthy men generally do not need extra calcium supplements (see page 81 ofThe Chemistry of Calm).
Note that it is calcium supplements that increases risk of calcium stones. Dietary calcium from foods decreases the risk of kidney calcium oxalate stones.
This is because calcium from foods binds to the oxalates in food such that the calcium-oxalate combination is not able to be absorbed by the intestines. Because calcium and oxalate doesn't go into the body, this reduces the amount of calcium and oxalate that has to be removed in the urine.
Article in medicinenet.com make the following conclusion...
"The study's investigators conclude that a high intake of dietary calcium reduces the risk of kidney stones but supplemental calcium increases the risk. They suggest that the risk of kidney stones among women taking supplemental calcium might be reduced by consuming the supplements with meals, particularly meals which contain the most oxalate"
When taking calcium supplements without the oxalates in food, the calcium by itself may be excessive and comes out in the urine, increasing the risk of stones.
Note that in general, healthy men should not need to calcium supplements. Kidney stones are more prevalent in men than in women.
New York Times writes that ...
"a diet containing a normal amount of calcium, but reduced amounts of animal protein and salt, may protect against stones better than a low-calcium regimen. ... In general data do not support the use of calcium supplements in most situations. ... Dosages of calcium above 2,000 mg per day are clearly associated with the formation of stones."
Dr. Carolyn Dean writes on HuffingtonPost how too much calcium when there is not enough magnesium and result in increase risk of kidney stones and other problems.
Others believe that calcium in the deficiency of vitamin K2 is the problem. Because it is vitamin K2 that directs calcium to the bones rather than to the soft tissues. Read more about it here.
Vitamin K2 helps moves calcium to where it belongs (in the bones) and not in the kidneys.
Paul Jaminet mentions the Nurses study that taking calcium supplementation increase the risk of calcium oxalate kidney stone.
It is not so simple. It is actually the balance between the fat soluble vitamins that is important. Laura Schoenfeld writes that ...
"In someone with kidney stones, vitamin A deficiency, vitamin K2 deficiency, and vitamin D excess are all prime suspects to be considered in terms of both absolute amounts and proportions between the vitamins."
Lifeguards with high vitamin D levels for example tend to have higher incident of kidney stones probably due to insufficient Vitamin A and K2 to balance the level of vitamin D.
Magnesium and Potassium To Reduce Kidney Stones
Use of calcium supplements without a proper balance of magnesium in the body can results in higher risk of stones. Calcium and magnesium ratio at the cellular level is what is important (not just at the blood level). Their levels are in turn affected by other various mineral level status. So whether one should supplement with calcium, or with magnesium, or both, or at what ratio really depends on the current cellular level of the various mineral status of the individual.
Among the 300 biochemical roles that magnesium plays a role in, one of them is that magnesium regulates your body's absorption and assimilation of calcium.
Dr. Carolyn Dean writes on HuffingtonPost ...
"Magnesium keeps calcium dissolved in the blood. Too much calcium along with too little magnesium can cause some forms of arthritis, kidney stones, osteoporosis and calcification of the arteries, leading to heart attack and cardiovascular disease."
Some of you may have heard the opposite notion of needing 2:1 ratio of calcium to magnesium. This is a myth as mentioned by Dr. Carolyn Dean who says ...
"Even the commonly agreed-upon ratio of 2:1 calcium to magnesium found in many supplements is a major stumbling block overcoming the overcalcification of our population. In fact, it's a myth. This so-called recommendation traces back to French scientist Jean Durlach who warned that the 2:1 ratio was a "never to be exceeded" level when considering calcium intake from all sources (food, water and supplements)."
She writes in her book The Magnesium Miracle that our bodies was most likely evolved to be optimized on a 1:1 ratio of calcium to magnesium...
"Research shows that the ratio of calcium to magnesium in the Paleolithic or caveman diet -- the ancient diet that evolved with our bodies -- was 1:1, compared with a 5:1 to 15:1 ratio in present-day diets" [page 21 -22]
Dr. Mercola recommends a 2:1 ratio of elemental magnesium relative to the elemental calcium for reduction in risk of kidney stones. [see reference]
Having adequate magnesium as well as potassium decreases the risk of stones because magnesium inhibit crystal formation. And potassium promotes urinary citrate excretion.
Many people are deficient in magnesium. Both magnesium and potassium tend to get "used up" or more depleted when under stress.
A study found that ...
"...for those stone vulnerable subjects having a high risk of potassium and magnesium depletion, to obtain the best therapeutic results, they should be provided supplementations of both potassium and magnesium together and also in the forms that would result in the delivery of an alkali loading effect."
Dr. Cannell writes that vitamin D along with calcium supplements in conjunction with a low consumption of potassium, magnesium, and fluid intake may increase risk of kidney stones. [reference] When vitamin D is excessive, it may result in high calcium levels which leads to increased risk of kidney stones. [reference]
In the book Real Cause, Real Cure it writes that real cause of kidney stones is nutritional deficiencies:
"Low levels of magnesium and vitamin B6 (pyridoxine) can increase the risk of kidney stone." [page 331]
The paper What Really Causes Kidney Stones lists a dozen ways to reduce risk of kidney stones. In particular it says that vitamin C is not a cause of kidney stones and that ...
"Magnesium is a pivotal treatment for kidney stones. If you don't have enough magnesium to help dissolve calcium, you will end up with various forms of calcification."
In one of his podcast (in regards to kidney stones), Chris also said ...
"...it’s fairly well established that ketogenic diets can contribute to kidney stones via other mechanisms. They do increase uric acid production, and low carb dieters, as Paul Jaminet has pointed out in his series on the dangers of zero-carb diets, typically can be inefficient at recycling vitamin C from its oxidized form. ... if there’s no compelling reason to be on a ketogenic or a very low carb diet, I would absolutely recommend balancing the diet macronutrient intake more, bringing some more carbohydrates back in, some fruit, some safe starches..."
Other news reports indicate that excessively high supplemental vitamin C raises risk of kidney stones in men. High supplemental vitamin D may also be a problem.
Lifeguards have higher incident of kidney stones (may be due to high vitamin D without enough K2).
Reducing Sugar Reducing kidney stone risk
As you now know, the proper balance of calcium and magnesium as well as other minerals is important. Excessive sugar can upset this balance and increase risk of kidney stones.
Sugar and high glycemic index foods tends to be acid-forming, and hence should be avoided to reduce risk of oxalate stones and uric acid stones.
Avoid soft drinks with phosphoric acid because these will reduce citrate levels in the urine.
Excessive sugar is one cause of obesity. Obesity is associated increased risk of kidney stones.
People with type 2 diabetics are more prone to have acidic urine and are at higher risk for developing uric-acid stones.
Purine Rich Foods, Proteins, and Uric Acid
Excessive excretion of uric acid may promote the formation of uric acid stones. Levels of uric acid in your blood rises during times of high cell turnover and increased cell breakdown. The kidneys are responsible for filtering the uric acid out of the blood.
Hyperuricosuria is when there is excessive excretion of uric acid due to either endogenous uric acid overproduction or excess dietary intake of purine-rich foods. Purine are metabolized into uric acid.
Purine rich foods are organ meats, kidney, mackerel, herring, sardines and mussels, and also yeast. New York Times writes that avoidance of the following foods may help prevent uric acid stones...
"Avoid alcohol, anchovies, sardines, oils, herring, organ meat (liver, kidney, and sweetbreads), legumes (dried beans and peas), gravies, mushrooms, spinach, asparagus, cauliflower, and baking or brewer's yeast."
This is not to say that these foods are bad or unhealthy. On the contrary, these are healthy foods for healthy people who have not had kidney stones and are not at risk for uric acid stones. It is normal for the body to break down purines into uric acid. The problem occurs when this metabolism is disrupted. For example, gout is an arthritic condition when uric acid builds up in the blood and causes joint inflammation -- in which case reducing purine-rich foods may be warranted under such conditions. That is why having gout is associated with increased risk of kidney stones.
Purines are found in animal proteins and animal products such as eggs. Excessive protein increases uric acid, calcium, and oxalate levels in the urine and therefore increase risk of stones. This is more true of meat protein (rather than plant protein) because meat protein has a higher sulfur content and produces more acid. Excessive protein makes the blood acidic and the body needs to restore pH balance by releasing calcium from the bones to the blood to alkalize it.
Although it is essential to consume adequate protein for your body's needs, excessive protein way beyond the body's need may not be so good.
Oxalates in Foods
Just because calcium oxalate stones are made from oxalate does not necessarily mean that one need to restrict all foods containing oxalates nor foods containing calcium. Sometimes yes and sometimes no. A urine test can determine one's oxalate level and help decide if one should go an a low-oxalate diet.
Some of the most healthy foods contains oxalates. And when consumed in the presence of calcium from food (not supplement), the oxalate binds with calcium in the intestine to reduce their individual absorption.
However, if doctor recommend a low-oxalate diet or if one want to take precautionary to limit the high-oxalate foods, here are the foods that are high in oxalate which you might want to avoid: spinach, rhubarb, beets, swiss chard, wheat germ, soybeans, peanuts, okra, chocolate, sweet potatoes, rice bran, bran flakes, almonds, miso soup, baked potato with skin, grits, bulgur, and navy beans. Here's is another list of high oxalate foods.
Moderate-oxalate foods include: grapes, celery, green pepper, red raspberries, strawberries, liver.[reference]
Note that the amount of oxalate content in food can vary considerably even in the same food depending on ripeness and location grown, etc. It also depends if the food is fermented or not. For example, unfermented soybeans are high in oxalate and increases the risk of stones. Unfermented soy that is used in many products is not a health food. Fermented soy is better in that it reduces the oxalate and phytic acid content.
One should also consume enough calcium in the form of foods (not as supplements) so that the calcium in the food binds and reduce the absorption of oxalate at the gut level. For certain individuals with leaky gut, the calcium oxalate may still leak through and into the blood system however. Many people with autoimmune conditions and autism has a leaky gut and an low-oxalate diet may be suitable for these sub-groups.
Although spinach contains a lot of oxalate, not all of that oxalate is absorbed because spinach also contains a significant amount of calcium that binds it.
You can learn more about low-oxalate diet in this Hawthorne University video.
Salt and other factors
Excessive salt can increase calcium in urine and increase risk of kidney stones. When kidneys excrete excessive sodium, calcium is also excreted as well.
New York Times article writes that ...
"The most important dietary recommendations for calcium stone risk are to increase fluid intake, restrict sodium, and reduce protein intake. Higher potassium intake can also lower the risk for calcium stones."
Urine contains natural inhibitors of kidney stones. These include citrate and magnesium which we mentioned previously as to how they are beneficial.
In general, fruits and vegetables provide elements that tend to inhibit stone formation. These inhibitors include citric acid, magnesium, potassium, fiber, and phytate. The phytate in certain high-fiber plant foods (as in grains and legumes) may help prevent calcium oxalate and calcium phosphate salts.
But high and excessive supplemental vitamin C may increase risk of kidney stones.[reference] But food sources of vitamin C is okay.
The following are controversial and debatable and studies have mixed results. Hence, no conclusion can be drawn as to how coffee, tea, and cranberry juice may affect the risk of stones. It may be that they have little or no effect.
- Some suggest that there is an association between stress and incident of kidney stones. Stress does deplete magnesium and potassium. Whether it is because stress causes the loss of vital minerals or from another mechanism is not clear. Association does not necessarily indicate a causation.
- Cranberry juice helps prevent urinary tract infections and may reduce struvite stones. However, cranberry juice increases amount of calcium and oxalate in the urine (increases risk of stones). But cranberry juice also increases the amount of citrate and magnesium (decreases risk of stones). Better to just drink water.
- Certain medications including possibly supplements may increase risk of stones. Some say that very high doses of vitamin C (more than 1000 mg/day) may increase risk of kidney stones because they can result in tiny oxalate that do not dissolve. However, article in Linus Pauling Institute says "the concern about the role of vitamin C in kidney stone formation, a source of speculation for several decades, appears to be no longer justified." [reference]. Others says the role of vitamin C in kidney stones is inconclusive. In any case, it is not a good idea for healthy people to extremely take high doses of any vitamin.
- Similarly, high doses of vitamin D (more than 4000 units per day) may increase calcium levels in the blood and increase risk of kidney stones. [reference WebMd]
- Although coffee and tea contains oxalate (increases risk of stones), they also have a diuretic effect which increases urine (decreases risk of stones). Some studies found that coffee/tea consumption is associated with lower risk. Other studies found that caffeine induces more calcium excretion in the urine. Better to just drink more water.
Natural Ways to Dissolve Kidney Stones
This article is only opinion at the time of writing. Author is not a medical profession and this is not a substitute for professional advice.