Is Cancer caused by a fungus that baking soda can treat?

The claim

A long-running online claim says two things at once. First, that cancer is really a fungal infection, usually named as Candida. Second, that because baking soda is alkaline, it kills the fungus and therefore treats the cancer.

The claim spreads well because it is simple, cheap, and sounds mechanical. It is also wrong on both halves.

The short verdict

Cancer is not a fungal infection. Sodium bicarbonate is not a cancer treatment.

Full Fact reviewed one popular version of this claim in January 2023 and found no evidence that sodium bicarbonate can cure cancer. It also noted that Cancer Research UK is not aware of any published clinical trial of sodium bicarbonate as a cancer treatment.

What cancer actually is

NCI puts it in one line: cancer is a genetic disease, caused by changes to the genes that control how cells grow and divide.

Those changes come from three routes. Copying errors when cells divide. Damage from things in the environment, such as chemicals in tobacco smoke or ultraviolet light. Or a change inherited from a parent.

NCI adds a detail that matters here. Each person's cancer carries its own combination of genetic changes, and even different cells inside one tumor can carry different ones. That is the opposite of an infection, where one organism is doing the same thing everywhere.

Our page on what cancer is walks through that biology in more detail.

Some infections do raise cancer risk. None of them is a fungus.

This is the part the claim distorts, so it is worth being exact.

Certain infections genuinely do raise cancer risk. NCI lists them: Epstein-Barr virus, hepatitis B and hepatitis C, HIV, human papillomaviruses, HTLV-1, Kaposi sarcoma-associated herpesvirus, Merkel cell polyomavirus, the bacterium Helicobacter pylori, and two parasites.

Look at that list again. Viruses, bacteria, parasites. No fungus appears on it.

The mechanisms are also specific rather than general. Some viruses disrupt the signals that keep cell growth in check. Some infections weaken the immune system. Some cause long-running inflammation that eventually damages tissue. In every case the cancer that follows is still a disease of altered genes. The infection is a cause upstream, not the tumor itself.

This is why HPV vaccination and hepatitis B vaccination prevent cancers. Removing a real cause works. Our overview of cancer risk factors covers which exposures have solid evidence behind them.

Where the acid idea came from

There is a real observation buried under this claim, and it has been stretched past recognition.

Tumors often sit in a more acidic local environment than normal tissue. Researchers have asked whether reducing that acidity might make some treatments work better. Full Fact notes that laboratory and mouse work has looked at sodium bicarbonate as a way to buffer tumor acidity, and that a 2020 review cautioned there is not enough clinical evidence to replace standard treatment with bicarbonate in water.

An interesting question in a mouse is not a treatment in a person. The gap between the two is exactly what clinical trials exist to close, and for this idea that work has not been done.

What sodium bicarbonate actually is, and what it does to you

MedlinePlus describes sodium bicarbonate as an antacid, used for heartburn and indigestion, and sometimes prescribed to make blood or urine less acidic in specific conditions.

Its guidance also sets limits that the online recipes ignore. Do not use it for longer than two weeks unless a doctor says so. Do not give it to children under 12 without medical advice. Tell your doctor if you have high blood pressure, heart failure, kidney disease, or recent bleeding in the stomach or intestine. It raises the sodium in your body, which matters on a sodium-restricted diet.

MedlinePlus lists warning signs that mean stopping the drug and calling a doctor immediately: severe headache, nausea, vomit that looks like coffee grounds, loss of appetite, irritability, weakness, needing to urinate often, slow breathing, swelling of the feet or lower legs, black or tarry stools, or blood in the urine.

Vomit that looks like coffee grounds and black stools are signs of bleeding in the gut. That is not a theoretical risk of large repeated doses. It is on the label.

Why this one is worth taking seriously

The FDA is direct about products sold as cancer cures. They may look harmless, but they can cause harm by delaying or interfering with treatment that works, and without review they can contain dangerous ingredients.

The FDA also lists the phrases that should make you stop reading. Treats all forms of cancer. Selectively kills cancer cells. More effective than chemotherapy. Attacks cancer cells while leaving healthy cells intact. The fungus-and-baking-soda claim uses nearly all of them.

What this story cannot tell you

• Ruling out this claim says nothing about the value of research into tumor acidity, which continues in laboratories.
• "No good evidence" describes what is known now. It is not a prediction about every future study.
• This page is about a claim, not about your treatment. Decisions belong with your care team.
• If you are already taking sodium bicarbonate for indigestion, nothing here says to stop. It says it is not a cancer treatment.

Sources

• Full Fact: Sodium bicarbonate is not 'lethal' to all cancers
• NCI: What Is Cancer?
• NCI: Infectious Agents and Cancer Risk
• MedlinePlus: Sodium Bicarbonate
• FDA: Products Claiming to "Cure" Cancer Are a Cruel Deception

How this page was made

An AI-assisted editorial system helped prepare this page. No named medical reviewer has reviewed it unless one is listed.

Cancer Explained is published by the National Cancer Information Foundation. It is not medical advice and does not suggest a test or treatment.

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