a pitcher of iced tea being poured into a glass of ice

Warning! August is the cruelest month when it comes to kidney stones.

If you have not had a kidney stone, congratulations. You do NOT want to experience the pain that accompanies passage of one of these suckers. Women have told us that passing a kidney stone is far more painful than giving birth. Strong men cry because of the pain. Do not assume you will escape unscathed. Kidney stones are amazingly common. It is estimated that 13% of men and 7% of women will develop a kidney stone sometime in their lifetime.

If you have already had a kidney stone, there is a strong chance that you could have another. One study suggested that the likelihood of experiencing another kidney stone within five years is almost 50%. Ouch! And it’s not just pain and suffering. Kidney stone complications can lead to life-threatening infections and kidney damage.

So what is it about the summer and August in particular that makes you more vulnerable to kidney stones? Studies have shown that the hotter it gets the more likely people will be hospitalized because of kidney stones. Hospital admissions for kidney stone emergencies peak in August and Google searches of kidney stones also surge during the summer, peaking in August.

Guess where the kidney stone belt is? Right! The southern part of the U.S. and states where it is hot-hot hot like Arizona.

So what is it about the summer that makes people so vulnerable to kidney stones? Experts have blamed dehydration as risk factor number one and that could well be true. When your urine is concentrated (as when the volume of your pee is decreased and the color is strongly yellow) there is a greater chance you will make a stone. The most common advice to avoid kidney stones is to drink a LOT of water to keep urine dilute.

There may be another reason why kidney stones are more common in the summer, especially in the south. Consider iced tea. John Miller, MD, is an assistant professor of urology at Loyola University Chicago Stritch School of Medicine. He suggests that iced tea consumption could be associated with kidney stones because iced tea contains a substantial amount of oxalate, which turns out to be a common component of many stones. According to Dr. Miller, the more oxalate in the diet, the greater the risk of kidney stones, especially in susceptible individuals.

Now this is pure speculation, but where do people LOVE iced tea? Right again. The south! Now that’s not to say that people don’t love iced tea in New England or Oregon. But in the south, iced tea is to adults what mother’s milk is to babies. We know folks who could easily drink 5 to 10 glasses of iced tea in a day and not think twice. Although this is still association and not causation, you will see that the map of the south where kidney stones are so common (the kidney belt) is where iced tea is the drink of choice.

Other foods high in oxalates include:

  • Beets
  • Blueberries
  • Dark chocolate
  • Cocoa
  • Figs (dried)
  • Nuts
  • Rhubarb
  • Soy (milk, burgers, tofu, yogurt, etc)
  • Spinach
  • Sweet potatoes
  • Strawberries
  • Swiss chard
  • Wheat germ, wheat bran

So, what should you be drinking in August (and other months) to reduce your risk of getting a kidney stone (or having another one)? Think lemonade! Lemons are high in citrate, which grabs onto oxalates in the digestive tract and prevents their absorption into the blood stream so they are less likely to concentrate in the kidneys. In truth, there have been few well-controlled trials to prove that less oxalate equals fewer stones. But there are some data to suggest that lemonade is linked to less risk of kidney stone formation. Here are some links you may want to check out:





Here is some additional information about reducing kidney stone risk:

Q. I read a letter from someone who drank lemonade to prevent kidney stones. I’ve had kidney stones for six years. I’ve been through two lithotripsies and taken sodium bicarbonate for two years. One of the physician assistants told me a year ago to drink a shot glass of lemon juice right before bedtime. I’ve had two ultrasounds since then and no kidney stones show up. I just wish my urologist had told me this.

A. Kidney stones are extremely painful, so preventive measures are most welcome. Doctors sometimes prescribe potassium citrate to block the formation of kidney stones. Because lemon juice also contains citrate, doctors have considered lemonade therapy to prevent kidney stones (Journal of Urology, April 2007). This calls for one or two quarts of unsweetened or low-sugar lemonade per day.

Pure lemon juice before bedtime can be hard on tooth enamel. Be sure to rinse well!

Q. I have a friend who was told she probably got her kidney stones from taking vitamin C and calcium supplements. There isn’t a daily vitamin supplement out there that doesn’t contain one or the other, if not both. What’s the story on this?

A. The story is complicated, because the studies have given contradictory results. Calcium supplements appear to increase the risk of kidney stones (American Journal of Clinical Nutrition, Jul. 2011).
Some people make more kidney-stone forming oxalate after large doses (2,000 mg) of vitamin C (Journal of Nutrition, Jul. 2005). The amount you would get from a multi-vitamin, however, is not likely to cause problems.

Q. I am lactose intolerant and have to take calcium supplements since I don’t drink milk. I have heard that these can cause kidney stones. Someone told me I should take Tums with calcium instead of calcium carbonate. Will this make a difference?

A. An article in the Annals of Internal Medicine (April 1, 1997, p. 497) showed that foods high in calcium help protect against kidney stones while calcium supplements increase the risk of stones by about 20 percent.

Regardless of the risk, taking your supplement with meals may protect you from any purported problem. You can also lower your likelihood of a kidney stone by making sure your diet is rich in potassium and magnesium from fruits and green leafy vegetables. Drink lots of liquids for added protection, but stay away from grapefruit juice which may boost the danger.

The active ingredient in Tums is calcium carbonate, which is also
found in many calcium supplements. We don’t think there is a substantial difference. We would encourage you to keep your calcium intake from supplements below 800 mg per day to be on the safe side.

Menopausal hormone replacement therapy has come under a lot of scrutiny during the last ten years because of the Women’s Health Initiative. This government-funded research was designed to determine the benefits and risks of HRT. It made headlines when the data showed an increased risk of cardiovascular problems among women taking hormones. There was also an increased risk of breast cancer.

Additional data collected during this study now show that women on estrogen are more susceptible to kidney stones. Those who continued taking HRT throughout the study increased their risk of stones by 39 percent. Women’s average risk of kidney stones at this age is about 5 to 7 percent. With HRT that went up to 8.5 to 10 percent. The investigators urge women and their doctors to weigh this risk when making decisions about HRT use. 

[Archives of Internal Medicine, Oct. 11, 2010]

Bottom Line:

• Do not become dehydrated (Do not let your urine get too yellow)
• Keep iced tea consumption moderate, especially in the summer
• Avoid grapefruit juice (it too is linked to stone formation)
• Drink lemonade if you are at risk of developing a kidney stone
• When in doubt drink water!
• Keep calcium intake from supplements under 800 mg per day
• Increase calcium intake from vegetables and other foods
• Consider more magnesium from green leafy veggies or from a supplement
• Consider probiotics periodically

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  1. JEFF
    Orange Calf.

    Yes, i believe this, I lived in Oklahoma for a few years. Dr. Pepper and Sweet tea flow like water that they should be drinking. Horrible obesity problem and just generally not caring about health. A co-worker is having a 3rd trip to hospital to break down the kidney stones that are too big. Back to sonic after this passes he says.uggggg.

  2. PSS

    Hi, I just had a large kidney stone broken up and I mentioned to the doctor I have begun taking magnesium citrate and he said not only is it more easily absorbed, but the citrate would of course be beneficial! My understanding is that the glycinate kind is not as easily absorbed and may be harder to digest. Good luck!

  3. CDR

    Melanie-What kind of magnesium-there are so many to choose from. And what dosage? I’ve taken magnesium glycinate 400 mg but not sure if this also works.

  4. Melanie

    I have been having stones for the past 37 years; first one when I was pregnant (not unusual for women who are prone to stones, I’m told). This is the first time I’ve seen a possible explanation for the timing of my stones. I’m always on the alert from July – Sept. for stones, but never could figure the reason. I do live in the south and tend to drink more iced tea in summer.
    I have had 2 Lithotripsies but rest of stones have been small enough to pass. One interesting fact about my stones is that as I’ve gotten older (60+yrs) the pain isn’t as bad. Whereas in my younger days I had what doctors call “kidney colic,” extreme pain when stone leaves kidney and travels down the ureter, now I no longer have this type of pain. It is only painful when the stone is moving around in the kidney. Now once it leaves the kidney I have a slight pinching sensation as it travels down the ureter. I guess my point is…. hang in there, stone sufferers, as you get older it may get less painful. I do try to follow a low oxalate diet (obtained on-line) and also take magnesium supplements (per doctor orders). Thanks Peoples Pharmacy for shedding light on the late summer timing of most of my stones!

  5. CB

    HCTZ is Hydrochlorothizide. My MD prescribes it as a mild diuretic for moderate high blood pressure.

  6. Penny E.

    I have had a stone that needed to be removed, and while I don’t ever want to have another one, eliminating all of these good foods might lead to other painful and harmful effects. Maybe moderation is the key. I take calcium citrate. Does that solve the problem of getting calcium while also consuming citrate which helps prevent stones? Also, what about the recent research coming out of Asia that says that green tea might actually prevent stones?

  7. Penny E.

    I have had a stone that needed to be removed, and while I don’t ever want to have another one, eliminating all of these good foods might lead to other painful and harmful effects. Maybe moderation is the key. I take calcium citrate. Does that solve the problem of getting calcium while also consuming citrate which helps prevent stones? Also, what about the recent research coming out of Asia that says that green tea might actually prevent stones?

  8. pd

    I am female, always watched my diet, exercised and drank lots of water, never soda. When the menopause hot flashes became strong I wanted something besides water. According to available research flavored seltzer seemed to be the answer and I drank tons of it. After about 8 months, a kidney stone hit out of nowhere. The emergency room nurses and doctors told me it was the C02. Haven’t touched it since.

  9. ss

    I have been having kidney stones since I was about 7 or 8 years old. I had them about every 2 to 3 years. Finally, about 5 years ago, my urologist told me I could talk a pill the rest of my life or I could avoid oxalates. As I did not want to take a medication I chose to reduce my oxalate intake.
    I avoid all dark sodas, tea, spinach, etc. and am just experiencing my first stone in five years. I had never heard about the lemonade/juice solution before so I think I will incorporate that into my regiment. As I have been told I will probably always have them if a dietary change lengthens the time between occurrences…. I’m on board.
    I am interested in some insight with regards to green tea or alternative teas.

  10. LDH

    I am what’s known in our family as a “tea Jenny”, meaning I drink lots and lots of it – hot tea, that is. My nephrologist said I should stay away from all teas. However, when I asked him about Roiboos (South African redbush tea), he had never heard of it. He looked it up on the internet while I was in his office and discovered it is oxalate-free and also caffeine-free. So, it is my tea of choice now.
    I too love all the things on the foods-to-avoid list. I eat them anyway and drinks LOTS of water. I keep a water glass by my bed and drink the whole glass when I get up for my middle-of-the-night trip to the “loo”. If I get up a second time, I drink a second glass. I haven’t had another kidney stone since increasing my water intake. (I drink about 6-8 glasses of water a day, more when i work up a sweat.)
    For those who have never had a kidney stone, let me try to explain the pain. I have never given birth so I can’t make that comparison. However, I have heard of animals caught in leg-hold traps who have chewed off a leg rather than die in the trap. If I could have eliminated the pain of passing a kidney stone by gnawing off a limb, I would have tried to!!!!

  11. Robert

    Does the same concern apply to hot tea? Black tea vs. green tea?
    I read recently that green tea can actually reduce the chance of developing kidney stones.

  12. ace

    What is HCTZ?

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