An explanation by a Long Island Registered Dietitian Nutritionist

Alkaline Diet

There are many diet fads and trends, most of which are based upon junk science rather than evidence-based science. Over the past several years, there’s been a lot of buzz about alkaline diets and how they lead to weight loss while reducing your risk of cancer, diabetes, and chronic disease. 

What is the alkaline diet, and does it work? As an RDN working with individuals to develop personalized nutrition plans for health promotion and disease prevention, science-based education is a foundation of nutrition therapy and diet counseling.  

The alkaline diet is based upon theory that by limiting acid-forming foods and eating more alkaline foods you will manage the pH of your blood which in turn will produce health benefits. Proponents of this plan state this diet can decrease the risk of medical conditions that include osteoporosis, arthritis, and cancer. There are now books, courses, supplements, and even alkaline water to help implement the diet. The question is… is there any value to an alkaline diet?

Though the idea is appealing, the reality is that the pH (the level of acidity or alkalinity) in the blood is tightly regulated and can’t be change through diet. When you eat, food is metabolized by the body and a residue of metabolic waste (ash) is left behind. This waste can be alkaline, neutral, or acidic. The proponents of an alkaline diet say that this ash can have a negative effect on your health.  

But this is theory, not fact or science. The fact is that different parts of your body have different pH levels, none of which can be changed by diet. For example, your stomach is highly acidic to enable you to break down food. But what is in your stomach is self-contained and doesn’t affect the pH of your blood. The liver has a neutral pH and the pancreas an alkaline pH. Saliva ranges from neutral to acidic.  

If, in fact, you could change the pH of your blood, it could be fatal. To be clear, our blood is always slightly alkaline, and if it were to fall out of its normal pH range, it could be fatal. That is exactly what happens to some people with poorly regulated diabetes when their blood becomes too acidic (ketoacidosis). This potentially deadly change in the pH is due to diabetes, not an acidic diet. As a Long Island Registered Dietitian and Certified Nutritionist, I must expose the falseness of the statement that diet will change the pH of your blood, and that changes in blood pH are healthful.

Here are the facts:

  • Meat, poultry, fish, dairy, and eggs leave behind an acidic ash
  • Starches and sugars leave behind a neutral ash
  • Fruits, nuts, vegetables, and legumes leave behind an alkaline ash

To sum it all up:  to follow an alkaline diet you need to reduce the intake of animal products and while increasing the intake of fruits, vegetables, nuts, and legumes, essentially a plant forward plan, exactly what is recommended for a healthful diet, sustainable weight loss, management of many chronic conditions, and overall wellness. 

More information on alkaline diets:
Webb, Densie PhD, RD. August 2021. Are There Any Health Benefits to Following an Alkaline Diet, Environmental Nutrition, p 3.