Alkaline Water

What is alkaline water?

Alkaline water has a pH above 7, usually between 8 and 9.5. It can occur naturally when water picks up minerals like calcium, magnesium, and bicarbonate from rock formations. It can also be produced artificially through electrolysis, where an electrical current splits water into alkaline and acidic streams. Bottled alkaline water is one of the fastest-growing beverage categories, driven by claims that it neutralizes acid in the body, slows aging, and prevents disease.

But how much of that holds up under scientific scrutiny? The answer is: not as much as the marketing suggests, though the picture isn't entirely black and white.

What the research actually shows

Your body maintains blood pH between 7.35 and 7.45 through tightly regulated buffering systems involving the lungs, kidneys, and bicarbonate buffers. Drinking alkaline water doesn't change blood pH. What you eat and drink changes urine pH, not blood pH ^[1]. This is the central problem with the "alkaline diet" theory: healthy bodies don't become systemically acidic from food or water.

A 2023 systematic review comparing alkaline, oxygenated, and demineralized water to regular mineral water found no significant differences in gut microbiota, urine pH, blood parameters, or fitness markers in healthy people ^[2]. The authors concluded that current evidence does not support health claims for alkaline water over ordinary mineral water.

That said, a few narrow applications do have some evidence behind them.

Acid reflux and pepsin inactivation

A 2012 in vitro study by Koufman and Johnston found that water at pH 8.8 irreversibly inactivated pepsin, the enzyme responsible for tissue damage in reflux disease ^[3]. This doesn't mean alkaline water cures GERD, but it suggests a possible adjunct role for people with laryngopharyngeal reflux. The study was conducted in a lab, not in patients, so real-world benefits remain unconfirmed.

Exercise-induced acidosis

A randomized controlled trial in combat sport athletes found that three weeks of alkaline water consumption (compared to table water) improved hydration status, buffered exercise-induced metabolic acidosis, and enhanced anaerobic performance ^[4]. The sample size was small (16 athletes), and results may not generalize to recreational exercisers.

Bone metabolism

Bicarbonate-rich alkaline mineral water has been shown to reduce bone resorption markers and parathyroid hormone levels, even in people with adequate calcium intake ^[5]. A study of 100 postmenopausal women with osteoporosis found that daily consumption of calcium- and magnesium-enriched alkaline water (pH 8.6) improved spinal bone density over 24 weeks ^[6]. However, researchers noted these effects may relate more to the mineral content than to the pH itself.

Animal longevity data

A three-year murine study of 150 mice found that those given alkaline water (pH 8.5) showed better survival rates starting from the second year of life compared to controls ^[7]. Histological examination of organs showed no pathology from long-term alkaline water consumption. Mouse studies don't directly translate to humans, but they suggest alkaline water is at least safe for long-term use.

Alkaline water vs. hydrogen-rich water

Many electrolysis devices produce water that is both alkaline and hydrogen-rich, which creates confusion about which component is responsible for observed effects. Molecular hydrogen (H2) has its own growing body of research: it acts as a selective antioxidant, neutralizing hydroxyl radicals without interfering with beneficial reactive oxygen species ^[8]. A pilot RCT in adults over 70 found that six months of hydrogen-rich water intake favorably affected telomere length, lower body strength, pain levels, and brain metabolism markers ^[8]. These benefits may have nothing to do with pH and everything to do with dissolved hydrogen.

The bottom line for healthspan

Alkaline water won't transform your health, and claims about cancer prevention or systemic pH shifts are not supported by current evidence. But it isn't harmful, and there are a few specific scenarios where it may offer marginal benefits: acid reflux symptom management, post-exercise recovery for high-intensity athletes, and possibly bone health through mineral content. If you're spending premium prices on alkaline water, you're likely overpaying for benefits you could get from adequate hydration with mineral-rich tap or filtered water. The minerals matter more than the pH.