Bottled alkaline water has become extremely popular, with sales of around $1 billion worldwide. But what is alkaline water exactly…and what does it do for you?

Alkaline Water Benefits

Every chemical compound in water sits somewhere along the pH scale from 0 to 14. Neutral compounds have a pH of 7. Anything lower is acidic…anything higher is alkaline. Most tap water hovers around neutral, with a pH of 6.5 to 8.5.

Bottled-water vendors now sell water that has been alkalinized artificially through a process called electrolysis, giving it a pH of 8 to 10. Numerous health claims have been made regarding alkaline water, but there is little evidence supporting most of the following claims…

  • Superior hydration: An oft-cited paper claiming that alkaline water is twice as hydrating as regular water ignores a widely accepted measure of hydration in favor of one made up for the purpose of the study.
  • Bone mineral density maintenance: There are no studies that show drinking alkaline water improves bone health or density.
  • Longevity: Some people try to extend lifespan by alkalinizing their blood, but your body has built-in mechanisms to maintain a pH of 7.4. No matter how much alkaline water you drink, your blood will revert to its normal pH.
  • Fighting cancer: One theory holds that cancer cells thrive in acidic environments and that alkaline water can help destroy this acidity—but there is no evidence to support this.
  • Aiding digestion: Some consumers believe alkaline water neutralizes the stomach acid that causes heartburn—but commercial alkaline water products are not strong enough to do this and are quickly neutralized when they encounter stomach acid, which is a strong acid.
  • Relieving gout: A 2024 Chinese study conducted at Guangzhou University of Chinese Medicine claimed that alkaline water eased gout symptoms…but the study was retracted due to data problems and fudged numbers.
  • Preventing cavities: Alkaline water won’t neutralize the acids associated with tooth decay unless you keep your mouth filled with it all day. And in fact, it is possible that keeping your mouth filled with alkaline water might be harmful to teeth, but this hasn’t been studied.

The only health benefit backed by science: Some commercial alkaline water may help prevent certain types of kidney stones. Cystine kidney stones form when the amino acid cystine builds up in urine. If your doctor identifies your kidney stone as cystine, you may benefit from alkalinizing your urine. But this alkalinization typically is done using potassium citrate tablets, which many patients get tired of taking. It may be possible to use alkaline water, but commercially bottled waters are not strong enough.

Alkaline Water Side Effects

Alkaline water has no direct harmful medical effects. But someone with cystine kidney stones who eschews potassium citrate in favor of weak alkaline water may fail to prevent new stones.

And there are moral harms—some purveyors of home electrolysis machines, which can be used to make water more alkaline, are marketed to cancer patients, giving them false hope…and selling alkaline water in the name of unsubstantiated health claims only parts people from their money.

Reality: If you really want to drink alkaline water, you likely have what you need to make it at home. One-quarter teaspoon of baking soda stirred into a glass of water has 20 times the amount of alkaline as bottled alkaline water. A month’s supply would cost you less than $1. Caution: Consuming too much sodium bicarbonate may affect electrolyte levels and lead to negative health consequences, including hypokalemia (low blood potassium), hypernatremia (high blood sodium) or worsening chronic kidney disease.

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