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We know in the cancer world there is a lot of misinformation, particularly related to nutritional advice. One of the most widespread myths revolves around the alkaline diet.

Before diving deeper into the alkaline diet theory, it is helpful to remember anyone can post information online regardless of their credentials. At first glance, what appears to be cancer information may actually be a sales pitch, opinion, or a personal testimonial advocating for a product from which they may even be getting an incentive. A vast amount of cancer information is available on the internet from a variety of sources including government agencies like the National Cancer Institute, expert health organizations, universities, non-profit organizations, as well merchants selling products, the general public, and unfortunately, even scam artists. 

The Theory

The alkaline diet theory is based on a single statement that cancer thrives in an acidic (low pH) environment. Therefore, the way to prevent and even cure cancer is to alkalize the body or create a high pH environment. Having spent more than 20 years as a cancer nurse, whenever I read something claiming one thing has the ability to cure (or even prevent) cancer, a huge red flag of suspicion raises.

As we know, cancer is not simply one disease. Instead, it is a category of more than 100 different diseases, of which many have various sub-types, as well. There is not one thing able to cure all of those variations of cancer. We know different cancers behave differently. For example, some cancer cells may have too many markers on them continuously signaling the cell to grow and multiply. A diet does not change the markers on a tumor.

The Diet

Foods including fruits (lemons, lime, grapes, kiwi, blueberries, etc.), vegetables (spinach, broccoli, cabbage, carrots, green beans, etc.), avocado, almonds, dates, and figs are all among the list of alkaline-promoting foods, which are allowed in the diet. Meat, dairy, eggs, grain, and alcohol are strictly excluded as they promote acidity. Interestingly, sugar is thought to be neutral as far as pH goes, which means the alkaline diet is one of the only “cancer diets” to not fervently oppose sugar. (Sugar is a whole topic for another day!)

Nevertheless, nearly all can agree eating a lot of refined sugars, those found in many junk foods, desserts, sodas, juices, etc. has been linked to a variety of health problems. Thus, it seems a bit surprising sugar is considered neutral on any diet specifically promoted for those with cancer.

The Science

The best and most widely spread rumors often have at least pieces of science in them, which make them more believable. Sometimes the bits of science are extorted to further the cause by claiming “proof.” Proponents of the alkaline diet proclaim some studies have shown an acidic environment helps cancer cells grow. Hence, you should eat certain foods in order to change the pH in your body, so it is inhospitable to cancer. Advocates of the diet claim by simply making this change, you can prevent or even cure cancer, if you already have it. They may add additional “proof” stating acidity promotes various diseases and illnesses, therefore clearly the smart choice is to make your body more alkaline.

The studies referenced for showing cancer cells like acidic environments were observed in the lab or in other words, in a petri dish. Proponents do not reference any studies conducted demonstrating how tumors actually behave in the human body. Why?

Well, it would be nearly impossible to alter the cell environment to create a less acidic environment in our bodies. For example, the stomach is very acidic. In fact, it needs to be for proper digestion. We would not want the stomach to be more alkaline, as this will make it harder to do its job. The alkaline diet also does not consider how pH in the body is actually maintained.

Here’s the spoiler alert: Food cannot change the pH of your blood. The body’s pH is tightly regulated by the kidneys within a fairly narrow range, in fact. If your kidneys are healthy, they are maintaining the balance. Eating an alkaline diet is not going to change the pH of your blood. Drinking alkaline water, in particular (this is a big part of the diet), can honestly do more harm than good.

Remember the stomach? Alkaline water is going to be neutralized when it meets stomach acid. If you are pouring large amounts of alkaline water into your body, you are forcing your stomach and your kidneys to work harder. Feel free to picture them working overtime.

Stomach acid is good. It helps us digest food and it also defends against invading pathogens. Neutralizing acid and trying to make the body more alkaline is not a good idea. The alkaline diet calls for monitoring of the body with pH strips as well, to test the saliva and urine. This testing is where proponents climb to the proverbial rooftops to shout, “We have proof, it works!” Those following an alkaline diet test their saliva and urine regularly to “ensure” they are staying in the right pH range.

And guess what? (No drum roll required.) After switching to eating more alkaline foods and drinking alkaline water, low and behold, the test strip shows it has become more alkaline. Supporters exchange high-fives in celebration of their efforts with confirmation from their test strips. (Spoiler alert: Don’t pop the champagne, just yet.)

The Reality Check

Here is what is actually going on in your body. Seeing your pH strips change to more alkaline, does not mean you are achieving a more alkaline environment in your body. It does reflect the body trying to do its job and get rid of all the excess alkalinity to maintain the blood pH in the body. Remember the kidneys, controlling acid-base balance in a tight range? So, the body is excreting it. It is working overtime to get rid of it while trying to maintain homeostasis, so the body can function as it should. This diet is causing your body to work a lot harder to get rid of all the excess alkalinity you are pouring in just to function properly.

Nothing you eat will actually change the pH of your blood, which would be the mark of making your body more alkaline. Diet does not have this effect. We can see it being excreted in the saliva and urine, but this reflects the excess waste products due to your newfound diet, not a true change in the environment of your body.

Research has shown alkaline diets and alkaline water are not supported in being promoted as being able to treat or prevent cancer. Anyone claiming otherwise is misunderstanding how pH is maintained in the body or they might possibly be manipulating those bits of science mentioned above. Consider this cancer myth busted.

Certainly, changing your diet to healthier choices like more fruits, vegetables, nuts, and beans over processed foods can have a benefit to your health. However, it is due to the nutritional content, not their alkalinity. Staying hydrated, focusing on a plant-based and minimally processed diet, ensuring your get adequate sleep, maintaining light to moderate activity, and learning how to cope with and minimize stress will help give your body exactly what it needs to best fight cancer.