Dear Dr. Benzi,

What is the deal with alkaline foods? What are people even talking about?

– R

Dear R,

This is a great question and one that I’ve often wondered about myself. I’ve broken down this question into three chunks.

First, what does alkaline mean? 

If you recall your high school chemistry, alkaline is the opposite of acidic and both are measured based on the concentration of hydrogen ions (pH). 7 is considered a neutral pH. A solution with a high concentration of hydrogen (pH less than 7) is an acid and solutions with low concentrations (pH greater than 7) are called a base or alkaline. Strong acids (think battery acid) and bases (think concentrated chlorine bleach) are reactive chemicals that are toxic to cells and will burn skin. Human blood is normally very slightly alkaline (pH 7.4) with a very narrow range (7.35-7.45). Even small deviations outside of this range can affect cellular function and be a sign of illness. Normally, the kidneys and lungs work to maintain blood pH within this range. Being alkaline outside of this range is not a good thing. As an experiment you can raise your pH by hyperventilating. Chances are you won’t feel healthy – you’ll feel dizzy, tingly and might pass out.

Second, what is an alkaline food?

This is where things start to get weird. You can measure the pH of any beverage or food, but this IS NOT what matters for the alkaline diet. The alkaline diet is based on the so-called “alkaline ash” hypothesis. This hypothesis proposes that foods that create alkaline ashes after they are combusted in a bomb calorimeter can reduce blood acidity and improve certain health conditions including osteoporosis. This is how orange juice (an acidic solution) can be considered an “alkaline food” according to the alkaline diet. The alkaline ash hypothesis is based on several big assumptions including:  a) that your body’s metabolism is similar to combustion in a bomb calorimeter; and  b) that the pH of food however metabolized will influence blood pH. 

Third, is there any evidence that alkaline diets improve health?

The assumptions behind the alkaline diet have been studied and have been proven false.  Specifically eating “alkaline foods” will not influence your blood pH and the alkaline diet does not cure any health condition.  That being said, the “alkaline diet” is a generally healthy diet and can lead to weight loss as it promotes fresh fruits and vegetables and prohibits processed foods and sugar. There is nothing magical, however, about this diet; most supplements marketed to enhance alkalinity have little to no evidence behind them. It may be easier to simply make decisions based on calories and caloric density (which does matter) rather than acidity/alkalinity (which does not).

Some takeaway tips to help you measure wellness fads on the bullshit-o-meter:

  1. There are many alternative medicine practices and diets that use sciencey words to market themselves. A little reading about the theory may convince you that it does not make sense physiologically (in terms of how the body works) or logically (in terms of, well, thinking and reason).
  2. While a lot of “science” and “theory” can be presented to support a health practice, the only scientific answer that really matters is: has it been proven to work in people?
  3. Almost any diet that has you restrict certain foods, particularly high calorie foods, will work to produce weight loss. This does not mean the magical theory behind the diet works.
  4. Supplements tied to magical diets are a good sign someone is after your money more than your health.


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