Can Alkaline Diets Cure Cancer?

The Short Answer

Eating plenty of vegetables, fruits, legumes and other plant foods can be part of a healthy diet. But that is very different from claiming those foods cure cancer because they are “alkaline.”

Your body regulates blood pH within a very narrow range through systems involving the lungs, kidneys and chemical buffers. What you eat can affect the pH of your urine, but it does not make your blood—or your entire body—meaningfully more alkaline.

Cancer can also create an acidic environment immediately around a tumor. That is real cancer biology. But it does not mean the patient’s entire body has become acidic, nor does it show that alkaline foods can reverse the process.

Can Alkaline Diets Cure Cancer? What the Evidence Shows

A systematic review published in BMJ Open examined the evidence linking dietary acid load, alkaline water and cancer. After searching thousands of records, the researchers found very little relevant human evidence and no randomized trials showing that an alkaline diet or alkaline water treats cancer.

The researchers concluded that promoting alkaline diets or alkaline water for cancer prevention or treatment was not justified by the available evidence.

Cancer Research UK similarly explains that there is no evidence that an alkaline diet can cure cancer. The American Institute for Cancer Research also notes that changing what you eat does not substantially change blood pH and that alkaline diets have not been shown to cure cancer.

Why doesn’t an alkaline diet change your body’s pH?

Different parts of the body naturally have different levels of acidity. The stomach, for example, is highly acidic because acid is necessary for digestion. Blood, on the other hand, is maintained within a narrow pH range.

If blood pH moves substantially outside that range, it can become a medical emergency. The body therefore regulates it continuously rather than allowing individual foods to determine it.

This is why someone eating an “alkaline” diet may see changes in urine pH without meaningfully changing blood pH.

Where Does the Alkaline Diet Cancer Claim Come From?

Part of the confusion comes from a genuine feature of cancer biology: many tumors develop an acidic microenvironment.

Cancer cells can have altered metabolism, and poorly organized blood flow within tumors can also contribute to local acidity. Researchers study this environment because it may influence how tumors grow, spread and respond to treatment.

But the direction of the argument matters.

The existence of acidity around a tumor does not demonstrate that an “acidic body” caused the cancer. And it does not demonstrate that eating alkaline foods can change the tumor environment enough to cure it.

But aren’t many alkaline-diet foods healthy?

Yes. This is one reason the claim can sound convincing.

Many versions of an alkaline diet encourage vegetables, fruits, beans and other minimally processed plant foods. These foods can absolutely form part of a nutritious diet.

Their potential health benefits, however, do not come from making the blood alkaline or creating an environment in which cancer cannot survive.

A healthy dietary pattern and an unproven cancer treatment are not the same thing.

Could Following an Alkaline Diet Be Harmful?

Eating more vegetables and other nutritious plant foods is not inherently dangerous for most people. The concern is what happens when the alkaline theory becomes restrictive or is treated as cancer therapy.

During cancer treatment, maintaining adequate calories, protein and nutrients can be particularly important. Strict diets that eliminate large groups of foods may make this harder for some patients, especially those already experiencing appetite loss, nausea, weight loss or difficulty eating.

The greatest risk occurs when someone delays, refuses or stops evidence-based cancer treatment because they believe changing their body’s pH can cure the disease.

What We Still Don’t Know

Tumor metabolism and the acidic tumor microenvironment remain active areas of cancer research. Scientists are investigating whether features of this environment can be targeted therapeutically.

That research should not be confused with the alkaline-diet claim. Developing treatments that interfere with tumor metabolism or the local tumor environment is fundamentally different from attempting to alter whole-body pH through food.

There is currently no established clinical evidence that an alkaline diet can shrink tumors, prevent recurrence, improve cancer survival or cure cancer.

Sources

Fenton TR, Huang T. Systematic review of the association between dietary acid load, alkaline water and cancer. BMJ Open. 2016;6:e010438. DOI: 10.1136/bmjopen-2015-010438.

Cancer Research UK. Alternative cancer diets. Evidence-based patient information addressing alkaline diets and cancer.

American Institute for Cancer Research. Does the Alkaline Diet Cure Cancer? Evidence-based explanation of alkaline diets, body pH and cancer.

Questions for Your Doctor

• Are there any foods or diets I should avoid during my treatment?
• Am I getting enough calories and protein during treatment?
• Could any supplements or alkaline products interfere with my treatment?
• Would speaking with an oncology dietitian be useful for me?