Question: What is the deal with alkaline foods? What are people even talking about? – R
Reply: Hello, 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 get interesting. And confusing.
You can measure the pH of any beverage or food, but this IS NOT what matters for most alkaline diets. The original alkaline diet was based on the “alkaline ash” hypothesis. This hypothesis proposes that foods that create alkaline ashes after they are combusted in a bomb calorimeter can reduce blood acidity. This is not considered a meaningful measure of alkalinity by most nutritionists. The current system used by nutritionists ranks foods on their “Potential Renal Acid Load” (PRAL), a measure based on how food is actually metabolized by the body. In general, meats and cheeses tend to be high PRAL foods based on how these proteins are metabolized. There are also many bullshit systems put forward by many pseudo-experts that have no connection with reality.
Here are a few examples to help clarify what these systems look like:
- Orange Juice: If you measure the pH of orange juice it is acidic. If you are trying to avoid acidic foods because of acid reflux, avoid orange juice. However, if you are trying to follow an alkaline diet, orange juice is OK because it does not contribute acid to the blood when it is metabolized (it actually has a negative PRAL meaning it contributes base).
- Meats and cheeses: If you are following a true alkaline diet, you will eat more fruits and vegetables (low PRAL) and less meats and cheeses (high PRAL).
- Sugar: If an “expert” advises you to avoid sugar because it is acidic, this could be a sign that they don’t understand real alkaline diets and are not a reliable expert. White sugar actually has a neutral PRAL. There are other reasons to minimize sugar in your diet, but acidity is not one of them.
Third, is there any evidence that alkaline diets improve health?
There is some evidence that alkaline diets (which also tend to be plant-based diets) may be good for slowing the progression and reducing complications of chronic kidney disease.1-4 Almost all other claims made for the alkaline diet are not based on any evidence. That being said, the “alkaline diet” is a generally healthy diet and can lead to weight loss as it promotes fresh fruits and vegetables. Most supplements marketed to enhance alkalinity have little to no evidence behind them.
Some takeaway tips so that you can answer questions like these yourself in the future:
- There are many alternative medicine practices and diets that use sciencey words to market themselves. Many of these have a grain of truth in them (e.g. alkaline diets may actually be good for people with kidney disease) but this does not mean the whole package is true.
- While a lot of “science” and “theory” can be presented to support a health practice. The only science that really matters is has it been proven to work in people.
- 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. Supplements tied to magical diets are usually a good sign someone is after your money more than your health.
1. Carrero JJ, Gonzalez-Ortiz A, Avesani CM, et al. Plant-based diets to manage the risks and complications of chronic kidney disease. Nat Rev Nephrol. 2020;16(9):525-542.
2. Adair KE, Bowden RG. Ameliorating Chronic Kidney Disease Using a Whole Food Plant-Based Diet. Nutrients. 2020;12(4).
3. Rodrigues Neto Angeloco L, Arces de Souza GC, Almeida Romao E, Garcia Chiarello P. Alkaline Diet and Metabolic Acidosis: Practical Approaches to the Nutritional Management of Chronic Kidney Disease. J Ren Nutr. 2018;28(3):215-220.
4. Passey C. Reducing the Dietary Acid Load: How a More Alkaline Diet Benefits Patients With Chronic Kidney Disease. J Ren Nutr. 2017;27(3):151-160.