To understand how to reduce your risk of kidney stones, you must first understand a little bit about the function of the kidneys. The primary function of the kidneys is to eliminate toxins, and they also play an important role in the maintenance of the mineral, acid and water levels in our bodies.
Your kidneys maintain water levels in your body by either hanging onto water or releasing extra water into the urine. The same is true of minerals and acids; the kidneys can either hang onto them or release them into the urine. Problems like kidney stones occur because some minerals (salts) are not very soluble and will form crystals, and then stones, if the urine becomes too concentrated.
Fortunately, a few simple dietary changes can help you lower your risk of developing kidney stones.
Drink more water
Imagine if you were to boil seawater on a stove. When half of the water boiled away, insoluble salts would concentrate and fall to the bottom of the pot. This is essentially what happens in the kidney — if you are dehydrated, the kidneys can pull pure water out of your urine. Then, your urine becomes so concentrated that the low soluble salts fall out of solution as stones.
The converse is also true. If you are over hydrated, the kidneys can release pure water into the urine and it becomes very dilute. This keeps the low soluble salts dissolved.
So, decreasing your risk of developing kidney stones involves either increasing water in the urine or decreasing the insoluble substances (mostly calcium, oxalate, phosphate and uric acid) in the urine. It turns out it is a lot easier to increase water intake than decrease the ingredients that make a stone.
Much is written and said about the number of glasses of water a person should drink in a day. You’ve probably heard 8 cups, but in reality, it’s not that simple. You have to take into account your body, and your circumstances. People who are more prone to kidney stones need more water than other people, so 8 cups does not necessarily apply to everyone. Also, you need to drink more water in August than in January because there is more loss of water through heat and sweating in the summer.
Fortunately, there is an easy way to know if you are drinking enough water — just look at the color of your urine. The goal is to have pale yellow urine; it needs to almost look like water. If the urine is dark yellow, it’s time to go grab a glass of water.
A short note about water: all fluids count as water. Unsweetened iced tea is 99 percent water. Even milk is 90 percent water. In fact, pure water is not the best fluid for preventing stones. Fluids that are high in citrate are the best for people prone to forming kidney stones. These fluids include lemonade, iced tea with lemon and diet lemon-lime soda.
Put away the salt shaker
So, staying hydrated is the best way to reduce your risk of kidney stones because it adds more water to your urine. But what about reducing the insoluble substances in the urine that form stones? Calcium and oxalate are by far the most important substances to consider. 80 percent of stones are made of calcium oxalate.
So, it would stand to reason that one should consume less calcium and oxalate, right? Wrong, and sort of wrong.
Actually, reducing calcium causes a person to make more stones. This is because dietary calcium binds to dietary oxalate and keeps it from being absorbed. Pretty much everything we eat or drink contains oxalate, so if you take away the dietary calcium, there is nothing to keep the dietary oxalate from getting absorbed, and the kidneys eliminate it in urine. Then, there is so much oxalate in the urine that, you guessed it, a calcium oxalate stone forms.
Reducing dietary oxalate is beneficial — but it’s hard to do — and if you have plenty of dietary calcium, the presence of oxalate is not a problem.
One exception you should know if you’re prone to kidney stones is spinach. Spinach contains so much oxalate that the calcium cannot bind it all and the extra oxalate gets absorbed. So, if you’re trying to avoid forming kidney stones, stay away from spinach.
There a few other dietary endeavors that can reduce stone formation. Table salt (sodium chloride) is very soluble, so you would think that it would not form a stone, and technically that is true, as kidney stones are never made of sodium chloride.
But that doesn’t mean you should load up on salt. Excess sodium can cause high blood pressure, so the kidneys eliminate sodium into the urine if we consume too much. However, because sodium and calcium are similar atoms, calcium often gets accidentally eliminated with the sodium, thus increasing the calcium level in the urine — and causing calcium oxalate stones to form.
Bottom line: put away the salt shaker.
Watch your red meat intake
The last dietary risk factor for kidney stones is red meat. Red meat is high in uric acid and phosphates. It also increases acid levels, which increases your risk of stone formation. It is not necessary to eliminate red meat altogether, just consume in moderation and choose fish or white meats when possible.
In summary, in order to reduce your risk of forming kidney stones, drink lots of fluids, enough to make the urine very pale yellow. Make sure you have plenty of calcium in your diet. Don’t eat spinach. Don’t salt your food. Consume red meat in moderation. Follow these prevention tips to help you steer clear of future kidney stones.