Question: A lot of people are talking about alkaline water. Does it help with all the things I have heard, like preventing cancer?

Answer: Claims about the benefits of alkaline water include effectiveness in treating heartburn as well as preventing cancer and cardiovascular disease. The theory goes that consuming water with a higher pH will balance the pH of your body, negating the effects of acidifying diets that, according to the theory, lead to a variety of health problems.

Remember the pH scale from 1–14, where 7 is neutral, below 7 is acidic and above 7 is alkaline or basic? If so, congratulations—you stayed awake through high-school chemistry! The problem with the theory that drinking alkaline water will balance your pH is that your body balances pH on its own, maintaining especially tight control over the pH of the blood.

The pH of different parts of the body varies for important reasons. Your stomach is highly acidic so that you can digest protein; your skin and mucous membranes are mildly acidic to prevent microbial growth; and so on (Schwalfenberg 2012). Ironically, many of the same websites that tout alkaline water for health also recommend consuming acidic apple cider vinegar and hot lemon water.

Very little quality research has been done on the role of diet pH in heart disease or cancer prevention (Fenton & Huang 2016), and claims that acidifying diets lead to osteoporosis aren’t supported by research (Fenton et al. 2009). We do know that alkaline water may be useful in treating acid reflux disease (Campagnolo et al. 2014), and that mineral water with higher pH can contribute important minerals like calcium and magnesium to the diet (Galan et al. 2002).

Alkaline water and alkaline diet promoters generally suggest consuming more fruits, vegetables, nuts and legumes, and eating less meat. So while alkaline water may not have the wide range of health effects it is purported to, adding more fruits, vegetables, nuts and legumes to your diet is definitely a good thing, and is associated with lower risk for heart disease and some cancers, whether or not it affects your body’s pH.