An alkaline diet cures cancer

An alkaline diet cures cancer
	FALSE
	"Cancer is caused by an acidic body, and eating alkaline foods, drinking alkaline water or taking alkalizing supplements can change the body's pH and cure or prevent cancer."
Domain	Health & Medicine
Tactic	Pseudoscience / Junk Science; Fraud or Scam;
Era	Current
First seen	1990s
Origin	Alternative health promoters including Robert O. Young, author of The pH Miracle (2002), drawing on a misreading of Otto Warburg's research on tumor metabolism
Last reviewed	2026-10-27
	Further reading: books on Health & Medicine

The claim that an alkaline diet cures cancer is promoted in books, websites, social media and wellness products. It holds that an "acidic" body causes cancer and other diseases, and that changing the body's pH through food, water or supplements can cure them. The claim is false. The pH of the blood is tightly controlled by the lungs and kidneys within a narrow range, regardless of diet; food can change the acidity of urine but not of the blood or tissues in any way that affects cancer. The acidic environment around tumors is a result of how cancer cells use energy, not a cause of cancer. One of the most prominent promoters of the alkaline theory was convicted of practicing medicine without a license and ordered by a civil jury to pay damages to a cancer patient.

The claim

Promoters divide foods into "acid-forming" and "alkaline-forming" categories and advise eating mostly vegetables, fruits and certain other foods while avoiding meat, dairy, sugar, coffee and processed foods. They sell alkaline water, pH test strips, supplements and programs. They often say that cancer cannot survive in an alkaline environment.

Origin

The idea draws partly on the work of German scientist Otto Warburg, who won the Nobel Prize in 1931 and observed that cancer cells often produce energy through a process that generates lactic acid even when oxygen is available, now called the Warburg effect. Alternative health promoters misinterpreted this as evidence that acidity causes cancer. Robert O. Young popularized the alkaline approach in The pH Miracle and other books, and promoted treatments at his ranch in California, including intravenous infusions of baking soda solution.

What the evidence shows

Blood pH is tightly regulated. The body keeps blood pH between about 7.35 and 7.45. Significant departures, called acidosis or alkalosis, are medical emergencies, usually caused by serious illness, not diet. The lungs and kidneys adjust continuously to maintain balance.
Urine is not the body. Diet can change the pH of urine, which is how promoters appear to demonstrate the effect with test strips. That shows the kidneys are doing their job of removing excess acid or base.
Tumors cause acidity. Tumors create an acidic microenvironment because of their metabolism. This does not mean that acidity causes cancer, and changing diet cannot alter the microenvironment of a tumor.
No clinical evidence. A 2016 systematic review published in BMJ Open by Tanis Fenton and Tian Huang found no evidence supporting an alkaline diet for treating or preventing cancer.
Cancers in alkaline tissue. Cancer can develop in many parts of the body, including tissues with naturally alkaline conditions.

Diets rich in vegetables and fruit are healthy for other reasons and are associated with lower risk of some cancers. But that has nothing to do with changing the body's pH.

Harms

The main danger is that people with cancer delay or refuse effective treatment. In 2016 Robert O. Young was convicted in California of practicing medicine without a license. In 2018 a civil jury in San Diego ordered him to pay more than $100 million to a woman with breast cancer who had followed his treatments instead of conventional care and whose cancer had advanced. Other patients who followed his advice and refused standard treatment died of their cancers. Intravenous baking soda and extreme diets can also cause direct harm.

Why it persists

The alkaline theory offers a simple explanation for a frightening disease and a sense of control over it. It is linked to diets that include genuinely healthy foods, so followers may feel better. Test strips provide apparent proof. And it fits wider distrust of conventional cancer treatment, which can be grueling.

Lessons for readers

Be wary of claims that one simple cause explains all cancers.
A measurable change, such as in urine pH, does not prove a claimed health effect.
Correlation between tumors and acidity does not mean acidity causes cancer.
Never replace evidence-based cancer treatment with an unproven diet.
Check whether promoters have faced regulatory or legal action.

Sources

Tanis R. Fenton and Tian Huang, "Systematic review of the association between dietary acid load, alkaline water and cancer," BMJ Open 6, no. 6 (2016).
American Institute for Cancer Research, guidance on alkaline diets and cancer.
Reporting on the 2016 criminal conviction of Robert O. Young and the 2018 civil verdict against him in San Diego (San Diego Union-Tribune and others).
Otto Warburg, "On the Origin of Cancer Cells," Science 123, no. 3191 (1956).