So what are kidney stones, exactly? Kidney stones are hard little substances made from chemicals in the urine. As the Kidney Foundation explains, "the stone may stay in the kidney or travel down the urinary tract into the ureter. Sometimes, tiny stones move out of the body in the urine without causing too much pain. But stones that don't move may cause a back-up of urine in the kidney, ureter, bladder, or urethra. This is what causes the pain."
Anyone who's ever had a kidney stone knows how painful the experience can be. (Many compare it to childbirth!) Unfortunately, 1 in 10 people will have at least one kidney stone during their lifetime.
Certain things can increase your risk, such as having had weight-loss surgery or having a history of cystine stones in your family, for example. Not to mention, your chance of developing a second kidney stone goes up dramatically after your first one. This, of course, brings up an important question: Is there anything that people can do to ward off these painful little buggers?
We invited one of our wonderful physicians, Dr. Justin Gould, to weigh in on 6 easy ways to prevent kidney stones. An important caveat, though: Keep in mind that implementing the following tips doesn't guarantee you'll avoid developing a kidney stone.
And as with all content on our blog, the information provided in this article is meant to be educational in nature, not medical advice. Always consult a physician regarding your specific health needs, especially if you've had a previous experience with kidney stones.
Tip #1: Stay well-hydrated.
DR. GOULD: Staying well-hydrated has been shown to have a beneficial effect on decreasing kidney stone formation and decreasing the size of kidney stones that are already present. But what does "well-hydrated" mean? Let's discuss types of fluids and the amount of fluid that can influence hydration.
In terms of the type of fluid you should drink, you want to choose something that's truly hydrational. Water, by far, is your best option. Caffeinated beverages like coffee, tea, and soda don't keep you hydrated due to the caffeine, which acts as a diuretic. And sports drinks, like Gatorade, aren't a good option either due to the high sodium. (I'll talk more about sodium in a moment.)
So water is the best liquid to drink. I usually tell my patients to have a goal of drinking two to three litres of water a day. A lot of patients ask how many glasses or how many water bottles of Poland Spring that is. If you're drinking the typical bottle of Poland Spring—the one that's 500 mL—you'd want to be drinking about six of those a day.
Pay attention to the colour of your urine because that indicates how hydrated you are. If you're well-hydrated, your urine should be somewhere between a very light yellow to a light lemonade colour. If it's transparent, meaning colourless and no yellow hue at all, you're overdoing it on your fluid intake. On the flip side, if your urine is an amber or dark orange, you're dehydrated.
Certain foods, like watermelon and cucumber, are also hydrational. So adding those to your diet can be a good idea, especially if you're not a big drinker. Bored by water? You could try adding flavouring. One of the best options for that is lemons, which brings me to my next tip.
Tip #2: Add lemons to your diet.
DR. GOULD: Lemons have the highest concentration of citrate, which is a stone inhibitor. Citrate helps prevent new stones from forming, and it helps any existing stones from getting larger. Adding three ounces of lemon juice daily to your diet is an easy way to help ward off kidney stones, particularly calcium oxalate stones, which are the most common.
Three ounces of lemon juice is equal to six tablespoons, and you can typically squeeze that out of two medium-sized lemons. Keep in mind that you must have real lemon juice to get the benefit. So freshly squeezed or store-bought lemon juice is fine. You want to have a pure concentration of real lemon juice, not lemon flavouring. We're not talking Crystal Light lemonade or anything like that.
For people who don't like lemons or patients dealing with GERD (gastroesophageal reflux disease), we can prescribe citrate pills.
Tip #3: Consume less salt.
Dr. GOULD: So the issue with salt is that when people have high salt in their diet, it can change the acid-base metabolism in the kidneys, and that can sometimes lead to higher stone formation. So trying to have a standard amount of salt or, even better, a low-salt diet is going to help prevent kidney stones from forming. A normal amount of salt should be 1500 to 2000 milligrams per day.
Tip #4: Cut down on animal protein.
DR. GOULD: Animal protein is a big risk factor for getting stones. If you eat a lot of red meat or even a lot of chicken, it's going to get broken down into amino acids in your body. Those amino acids would cause you to have a more acidic load going to the kidneys. And that acid load can be a risk factor for stones.
People who have a more alkaline diet—meaning a diet rich in vegetables and more fruits—those patients seem to have less frequency of getting stones than those who have high acid and high animal-protein diet.
Tip #5: If you've had a kidney stone, talk to your urologist about getting a metabolic workup.
DR. GOULD: If you've had a kidney stone, you're at greater risk for having another one. Knowing what type of stone you had can help guide you and your doctor on lifestyle changes and treatment options if needed. Talking to your urologist and getting a metabolic workup can help us understand your stone-risk profile.
Tip #6: Don't let the word "calcium" fool you if you've had a calcium oxalate stone.
DR. GOULD: Calcium oxalate stones are the most common type of kidney stones. I would say they are 80 to 90% of all the stones that we see at Greater Boston Urology. The reason the stones form can be from a combination of things. It can be from too much calcium in the urine. It can be from too much oxalate in the diet. The thing I want to warn people of . . . often when patients hear the words "calcium oxalate kidney stones," they think they need to reduce the amount of calcium they eat, and actually that's not true.
So especially for a lot of females that get kidney stones, a lot of them are at risk for osteoporosis. So we tell them to maintain their normal calcium levels. And if your calcium levels are low, then you might even need to still get supplemented on a calcium supplement.
But again, for everyone who has stones who comes to see us, we can do a metabolic evaluation to check their electrolytes. We can actually see what the calcium level is in the blood, and we can see what the calcium level is in the urine. There can be a variety of reasons for having high calcium in the urine. For example, it can be due to something hormonal, like having a parathyroid gland lesion on a parathyroid gland in the neck, which is the gland that regulates calcium in the body.
Bottom line: Just because you have a calcium oxalate stone, don't assume you need to limit your calcium. Calcium is important to your diet.
In terms of the oxalate levels, most oxalate is from the diet. There are some very rare genetic diseases where oxalate is not metabolized in the liver correctly, and that can lead to having high oxalate levels. But the majority of people that we see, the oxalate is something that's from their diet.
The challenge is that oxalate-rich foods are also incredibly healthy foods, like spinach, beets, rhubarb, and nuts, just to name a few. We don't want people to eliminate healthful foods from their diet. Instead, you want to be mindful about how much oxalate-rich foods you eat every day. For example, having a spinach smoothie every day might not be the wisest decision.
Another tip is combining a calcium source with oxalate-rich food. Again, this might sound counterintuitive if you suffer from calcium-oxalate stones, but when you eat calcium-rich food and oxalate-rich food together, the calcium and oxalate bind together in the stomach and intestines before reaching the kidneys. This makes it less likely that stones will form in the urine. So, for example, you might eat walnuts—an oxalate-rich food—with calcium-rich food like yoghurt.
By the way, it's not just calcium-oxalate stones that are influenced by what you eat. The second most common stone we see is uric acid stones. And they're usually caused by foods rich in purines. Things like red wine, red meat, and sweetbreads, just to name a few examples. It's actually the same mechanism where gout comes from. So when you have crystals that form on your toe, that's gout. And when you have crystals that form in the kidney from uric acid, then that's called a uric acid stone.
Uric acid stones have to do with the acidity of a person's diet. So if you're eating a high animal protein diet, this can cause an acid-base disturbance and a high acid load going into the kidney, which would then predispose you to forming uric acid stones.
I know all of this can sound confusing or overwhelming. Talking to your doctor or a registered dietitian like we have at GBU can go a long way in helping you make the right dietary decisions based on your metabolic workup and stone-risk profile.
Interested in making an appointment with Dr. Gould or one of our other fabulous urologists?
Dr. Gould works out of our Milton, Dorchester, and Dedham locations. We also have Care Centers in Framingham, the south shore, and Cape Cod. Consider making an appointment with one of our urologists. You can also make an appointment with our registered dietitian, Elle Wittneben, who sees patients online or in Dedham.