The Cooper Institute

Founded in 1970 by the "Father of Aerobics"
Kenneth H. Cooper MD, MPH


The Alkaline Diet: Help or Hype?

Posted in

Friday, Mar 26, 2021

How is it measured  |  Effects  |  Takeaway

As Americans, we sometimes take our liberties for granted. For example, the First Amendment to the U.S. Constitution guarantees all legal citizens the right of free speech. This privilege applies not only to the spoken word, but also to printed materials as well. Thus, anyone can write a diet book or have a nutrition website and make whatever claims that they wish to make. You may be surprised to learn that many of the best-selling diet books over the past several decades have been written by individuals who have little or no training in nutrition. During this time, rates of obesity have soared worldwide, which suggests that most of these diets do not result in long-term weight control.

What is the Alkaline Diet?

Because there are an endless number of diet programs available, one must have a gimmick in order for their diet to stand out from all the rest. For example, one diet might urge us to ‘eat like a caveman’, while another may emphasize avoiding high glycemic index or processed foods. One of the latest dietary fads is The Alkaline Diet. This approach is based on the acid/alkali theory regarding disease. When our body breaks down the foods we eat, the waste products are sometimes called ‘ash.’ The ash can be acidic or alkaline. The pitch is that by consuming more foods that produce alkaline ash and fewer foods that produce acidic ash, you can change the pH of your body. This in turn will lead to weight loss, increased energy, and a decreased risk of chronic conditions such as cancer, arthritis, osteoporosis, kidney and gall stones, etc. These claims should remind us of a wise old saying: “If it sounds too good to be true, it probably is.”

Before continuing, lets discuss a bit of chemistry?

The pH continuum is a numerical scale between 0 and 14. Numbers at the lower end of the scale indicate strong acids, while numbers at the upper end represent strong bases (alkaline). For example, tap water has a pH of 7.0, which is neutral (neither acidic nor alkaline). It is important to note that pH levels vary throughout the body. Blood normally has a pH of 7.4, while the pH of muscle tissue at rest is 7.2. Bile and pancreatic juices typically have a pH of about 8.0, while our stomach is always very acidic with a pH of approximately 1.7. The very low pH value in the stomach is due to hydrochloric acid, which helps to break down food during the digestive process. None of these pH values are the least bit controversial; in fact you will find this information in all standard medical textbooks. It is also well-established that some foods are a bit more on the acidic end of the continuum, while other foods are more alkaline. 

The major premise behind The Alkaline Diet is that our body is too acidic because we consume too many acidic ash-producing foods, and that this condition increases the risk of chronic disease. By limiting acidic foods and emphasizing alkaline foods, proponents of the diet claim that this shift will make the body less acidic, which will in turn decrease the risk of disease. In particular, the Alkaline Diet claims to change the pH of the blood. At this point, a review of human physiology is in order! One of the major functions of the kidneys is to regulate the acid-base balance of the body. This includes keeping blood pH at a constant level of 7.4. Despite what proponents of the diet claim, there is no scientific evidence that what you eat or drink will change the pH of your blood (or anything else in your body). Another misconception supported by this dietary approach is that you can test your body’s overall pH by testing the pH of your urine. Any board-certified urologist will tell you that the pH of urine is not an indicator of pH in the rest of your body. Regardless of the pH of your urine, if your kidneys are functioning normally, the pH of your blood will always be 7.4. In fact, any licensed health-care professional will tell you that a significant deviation from this number is quite lethal!

What are the effects of the Alkaline Diet?

At this point, you may be wondering about the effects of the Alkaline Diet on weight loss. Here’s where the gimmick comes into play. By limiting the countless ‘acidic-forming’ foods in your diet, and by eating more ‘alkaline-forming’ plant-based foods, you will automatically cut down on calorie intake. What happens when you cut down on calories? You lose weight! The problem is that by limiting or eliminating so many foods, we are missing out on a wealth of essential nutrients. The Cooper Institute would be the first to agree that most people should cut back on soda, energy drinks, processed meats, and other foods that might exist closer to the acidic end of the continuum. However, other somewhat acidic foods such as fish, citrus fruits, and whole grains are great sources of protein, vitamins, minerals, and antioxidants. Plus, don’t forget about all the fiber in fruits and whole grains!

Another disadvantage of the Alkaline Diet is that it does not promote the concept of regular exercise for good health and weight control. We have known for decades that diet by itself is simply not very effective for long-term weight control, and that regular exercise along with a prudent reduced-calorie diet is much more likely to result in long-term weight control than either one by itself.

Does it really work? 

Some individuals claim that there is proof that the Alkaline Diet prevents cancer and a host of other diseases. Actually, there is no proof of this at all. If there was, it would likely be the lead story on the national news, on the front page of every newspaper and magazine, and be featured prominently on the American Cancer Society, American Diabetes Association, and American Heart Association websites. The fact is that not a single evidence-based health organization endorses The Alkaline Diet.    

When a diet sounds too good to be true, it’s wise to be skeptical. An endorsement from a Hollywood celebrity or a great NFL quarterback is typically not based on good science. As a nation, we would do well to follow the current public health guidelines for dietary intake: Consume more fruits, vegetables, legumes (beans and peas), whole grains, low-fat dairy (or fortified soy), raw nuts, and fatty fish.  Consume less added sugar, saturated fat, processed meats, and sodium, and be sure to get at least 150 minutes per week of moderate intensity aerobic exercise. Don’t forget to do your strength training at least twice a week as well.

What about the expensive ‘alkaline water’ products on the market today? Save your money! Drinking alkaline water will not result in any change whatsoever in your body’s pH.