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UCI-led study: Alkaline water doesn’t help prevent kidney stones

Researchers find that levels are too low to offer benefit

January 19, 2024
uci health urologist and kidney stone expert dr. roshan patel in an operating room wearing blue scrubs
UCI Health kidney stone expert Dr. Roshan Patel says the team's
findings may help consumers choose other treatments that can
help prevent kidney stones. Credit:Steve Zylius/UCI

Orange, Calif. — Bottled water marketed as "alkaline water" is unlikely to be an effective alternative for prevention of recurrent urinary stones, according to a UCI-led study.

"While alkaline water products have a higher pH than regular water, they have a negligible alkali content, which suggests that they can't raise urine pH enough to affect the development of kidney and other urinary stones," says UCI Health urologist Dr. Roshan M. Patel, the paper’s senior author. 

The paper was published in the January issue of The Journal of Urology®.

Popular alternative to pills

Consumption and sales of alkaline water, also called high pH water, have increased sharply in recent years. Proponents claim various health benefits, including improved hydration and increased urinary pH.

Tap water has a typical pH of around 7.5. Alkaline water is manufactured to have a pH in the range of 8 to 10.

Raising pH is a key strategy to prevent kidney stones in patients who have previously had them.

The recommended treatment — potassium citrate tablets — is often not followed because it requires taking large pills several times daily. Raising urinary pH by consuming alkaline water could be an attractive alternative to preventing kidney stones, says the study’s authors.

‘Trivial’ alkali content

Patel's team measured the pH of five commercially available alkaline water products. The team also reviewed published data on other types of drinks and over-the-counter products with the potential to raise urinary pH.

The five brands tested had a pH of around 10.

One product contained a small amount of citrate, which was not listed on the product label. Otherwise, the tested alkaline waters had no organic anions that could be metabolized into alkali by the body.

At a pH of 10, the tested products would have an alkali content of just 0.1 milliequivalent per liter (mEq/L). That's a "trivial" concentration compared to the body's typical metabolic acid production of 40 to 100 mEq/L per day, according to the authors.

More effective, less costly alternatives

In contrast, some other commercially available products do have the potential to increase pH — notably including orange juice, which has an alkali content of up to 15 mEq/L. Orange juice also has the lowest estimated cost to achieve the target alkali concentration of 30 mEq per day.

Baking soda was one of the most effective and cost-efficient alternatives, although there are concerns related to its high sodium content.

Newer products dissolvable in water also appeared to provide useful and affordable options. The article includes a graphic table comparing the alkali content of various products and their costs in reaching target alkali levels.

"Our findings may help to guide the selection of other treatments, including beverages and over-the-counter products, for preventing recurrent urinary stones," adds Patel, who is the director of the UCI Health Kidney Stone Center. He’s also an assistant professor and chief of Endourology at the UCI School of Medicine Department of Urology.

The researchers note the limitations of their laboratory study and emphasize the need for clinical trials of the options for raising urinary pH.

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UCI Health is the clinical enterprise of the University of California, Irvine, and the only academic health system in Orange County. Patients can access UCI Health at primary and specialty care offices across Orange County and at its main campus, UCI Medical Center in Orange, Calif. The 459-bed, acute care hospital, listed among America’s Best Hospitals by U.S. News & World Report for 23 consecutive years, provides tertiary and quaternary care, ambulatory and specialty medical clinics, behavioral health and rehabilitation services. UCI Medical Center is home to Orange County’s only National Cancer Institute-designated comprehensive cancer center, high-risk perinatal/neonatal program and American College of Surgeons-verified Level I adult and Level II pediatric trauma center, gold level 1 geriatric emergency department and regional burn center. UCI Health serves a region of nearly 4 million people in Orange County, western Riverside County and southeast Los Angeles County. Follow us on Facebook, Instagram, LinkedIn and Twitter.