Researchers have found a potential supplement and cause.
People who have passed a big kidney stone dread a second episode. New research may lead to more help.
A small stone may show up in your urine, and cause you little or no discomfort. But big stones are unpleasant, to say the least. Most are made of calcium oxalate crystals, although stones can form with other minerals. They may be as small as a grain of sand, or as large as a pearl or even a golf ball. Some are smooth and some are jagged, but they’re usually yellow or brown.
Repeating urinary tract infections, digestive problems, high blood pressure, diabetes, and obesity can increase your risk — and because those problems are more common, so are kidney stones. Up to 12 percent of men and 7 percent of women run into them.
The first symptom may be frequent or painful urination. Your urine may be cloudy or be suffused with blood, appearing pink, brown, or red. If a stone moves through your urinary tract, you may feel intense pain in your back, belly, or groin. Often the pain starts late at night or early in the morning, when your ureter tends to be constricted. The pain may stick, or come and go in waves, separated by about 10 minutes.
See a doctor if you have severe pain, trouble urinating, blood in your urine, or pain accompanied by nausea, vomiting, chills, or fever — which could indicate an infection.
Scarily, the chances of developing another stone may be around 50 percent. Drinking lots of water will help dissolve the crystals in your urine, and depending on the content of the stone, your doctor may advise you to change your diet.
Some doctors advise taking potassium citrate (CA), or citrate salts, which can slow crystal growth. Fredric Coe, MD, who heads the kidney stone program at the University of Chicago, reviewed several studies and concluded that among patients with a history of calcium and other kinds of kidney stones who were given citrate salts, beginning at dosages of 50 mg a day, less than 15 percent formed new stones or showed growth of retained fragments, compared to 52 percent of those given placebo.
Researchers have also found evidence that a natural fruit extract, hydroxycitrate (HCA), which is similar to potassium citrate, may do a better job.
In head-to-head studies of CA and HCA, researchers used special microscopes to determine that HCA formed a stronger bond with crystal surfaces, inducing a strain that seemed to push the crystal to dissolve. The researchers then gave seven people the supplement for three days, establishing that HCA is excreted through urine, a requirement to create a supplement to treat the problem. This research remains groundwork: further studies would need to establish a safe, effective dosage.
A lack of a particular bacterium, Oxalobacter formigenes, may be at the root of the problem that allows kidney stones to form. This bacterium helps ferry oxalate out of the body, and people who get kidney stones tend to harbor less of it. One 2016 study found that fewer than half of a sample of healthy young adults had enough of the bacterium in their bodies.
What can you do? The most important step is to drink lots of water. Ask your doctor about citrate salts and other specific advice. Don’t jump to the conclusion that having calcium oxalate stones means you need to eat less calcium — in fact, the opposite is true. Calcium in the digestive tract binds to oxalate from food and keeps it from entering the blood, and then the urinary tract, where it can form stones. You may need to eat more dairy or take calcium supplements and cut back on salt and protein. A meta-analysis from the prestigious Cochrane organization found that eating a normal amount of calcium, and a low-salt, low-protein diet over five years reduced calcium stones.
People who hear they’ve passed a calcium oxalate stone often go looking online for a list of foods to avoid, and try to tally up how much oxalate they’re eating. The trouble is that the lists vary widely in the reported oxalate content. Also, many foods that we eat when we’re being especially nutrition-conscious fall into the high-oxalate list, including spinach, almonds, cashews, avocados, tofu, soy milk, brown rice, yams, and millet.
You might try substituting low-oxalate foods for high ones. So, instead of raspberries, eat strawberries, blueberries, or cherries. Replace oranges and grapefruit with melon, mango, and cantaloupe. Eat kale rather than spinach. Choose a cream sauce rather than a tomato sauce on pasta.
An African folk remedy for calcium stones, a liquid extract from the plant Phyllanthus niruri, has some backing from Western science, but it didn’t show benefits in a 3-month study reviewed in the Cochrane analysis.
Stones can form that are not made of calcium oxalate, so if you pass a stone in your own toilet try to fish it out and take it to a lab (your doctor can also give you a screen to catch it from your urine stream), or be sure you find out what kind of stone you have before you leave a hospital. If you eat a lot of meat and fish you may form a stone from uric acid along with calcium, or uric acid alone. Kidney infections cause struvit” stones. Cystine stones are caused by a genetic disorder.
March 25, 2020
Janet O’Dell, RN