If you’ve ever had a kidney stone, you surely remember it. The pain can be unbearable, coming in waves until the tiny stone passes through your urinary plumbing and out of the body. For many, kidney stones aren’t a one-time thing: in about half of people who have had one, another appears within seven years without preventive measures. Preventing kidney stones isn’t complicated, but it does take some determination. Kidney stones form when certain chemicals become concentrated enough in the urine to form crystals. The crystals grow into larger masses (stones), which can make their way through the urinary tract. If the stone gets stuck somewhere and blocks the flow of urine, it causes pain. Most stones occur when calcium combines with one of two substances: oxalate or phosphorous. Stones can also form from uric acid, which forms as the body metabolizes protein. Preventing kidney stones means preventing the conditions that support their formation. I asked Dr. Melanie Hoenig, an assistant professor of medicine at Harvard-affiliated Beth Israel Deaconess Medical Center, for the top ways to prevent kidney stones.
Here are her recommendations: Drink plenty of water: Drinking extra water dilutes the substances in urine that lead to stones. Strive to drink enough fluids to pass 2 liters of urine a day, which is roughly eight standard 8-ounce cups. It may help to include some citrus beverages, like lemonade and orange juice. The citrate in these beverages helps block stone formation. Get the calcium you need: Getting too little calcium in your diet can cause oxalate levels to rise and cause kidney stones. To prevent this, make sure to take in an amount of calcium appropriate to your age. Ideally, obtain calcium from foods, since some studies have linked taking calcium supplements to kidney stones. Men 50 and older should get 1,000 milligrams (mg) of calcium per day, along with 800 to 1,000 international units (IU) of vitamin D to help the body absorb the calcium. Reduce sodium: A high-sodium diet can trigger kidney stones because it increases the amount of calcium in your urine. So a low-sodium diet is recommended for the stone prone.
Current guidelines suggest limiting total daily sodium intake to 2,300 mg. If sodium has contributed to kidney stones in the past, try to reduce your daily intake to 1,500 mg. This will also be good for your blood pressure and heart. Limit animal protein: Eating too much animal protein, such as red meat, poultry, eggs, and seafood, boosts the level of uric acid and could lead to kidney stones. A high-protein diet also reduces levels of citrate, the chemical in urine that helps prevent stones from forming. If you’re prone to stones, limit your daily meat intake to a quantity that is no bigger than a pack of playing cards. This is also a heart-healthy portion. Avoid stone-forming foods: Beets, chocolate, spinach, rhubarb, tea, and most nuts are rich in oxalate, and colas are rich in phosphate, both of which can contribute to kidney stones. If you suffer from stones, your doctor may advise you to avoid these foods or to consume them in smaller amounts. For everyone else, particular foods and drinks are unlikely to trigger kidney stones unless consumed in extremely high amounts.
Some studies have shown that men who take high doses of vitamin C in the form of supplements are at slightly higher risk of kidney stones. That may be because the body converts vitamin C into oxalate. Related Information: Eat, Drink, and Be HealthyVitamins & Supplements Home Related to Vitamins & Supplements Diet & Weight Management Study: Vitamin D Supplements May Not Raise Risk for Kidney Stones However, researchers found age, weight and gender are factors By Mary Elizabeth Dallas THURSDAY, Oct. 17 (HealthDay News) -- If fear of kidney stones is preventing you from using vitamin D supplements, a new study could ease your mind. Taking vitamin D does not increase the risk for kidney stones, the study found. People's age, gender and weight, however, may play a role in developing the condition. Previous research suggested that adequate levels of vitamin D might help protect against a number of diseases, including certain forms of cancer. "Our results may lessen concerns by individuals about taking vitamin D supplements, as no link was shown between such supplementation and an increased risk for kidney stones," study leader Cedric Garland, of the University of California, San Diego School of Medicine, said in a university news release.
The new study used data on more than 2,000 adults of all ages. After following the participants for 19 months, researchers found that only 13 people reported being diagnosed with a kidney stone during that time. The study, which appears Oct. 17 in the American Journal of Public Health, did show that being older or having a higher body-mass index (BMI) were both risk factors for this condition. BMI is a measurement of body fat based on height and weight. Men also are at greater risk for kidney stones than women, the study found. But vitamin D users are not, it suggested. "Mounting evidence indicates that a vitamin D serum level in the therapeutic range of 40 to 50 [nanograms per milliliter] is needed for substantial reduction in risk of many diseases, including breast and colorectal cancer," said Garland, an adjunct professor with the division of epidemiology in the department of family and preventive medicine. Garland added that supplements typically are needed to achieve this blood level of vitamin D.
They found that the prevalence of vitamin D deficiency (< 20 ng/ml) was 56% in stone formers and 44% in controls (P <.001), with median vitamin D levels of 18 ng/mL versus 23 ng/mL. After a fully adjusted analysis, those with vitamin D deficiency were more than twice as likely to develop a kidney stone. In April of 2016, Dr. Girón-Prieto and colleagues did a case control study of 366 subjects, 239 of which had a history of kidney stones. They also found that those with low 25(OH)D levels were more likely to develop kidney stones. This goes to show that face validity (sounds right) can be wrong, sometimes with significant consequences. The cholesterol/fat theory of heart disease had face validity, so we started eating low cholesterol/fat diets. However, such diets did not reduce heart attacks; instead, they contributed to the obesity epidemic. It just goes to show why one has to be careful of assumptions. Vitamin D may sound like it will cause kidney stones, but the opposite is actually true.