Cancer Education

Do alkaline diets stop cancer?

sliced lemons and limes

Some people believe that eating foods that make the body’s pH more alkaline can help prevent cancer, help with cancer treatment and slow the growth of cancer cells. Is there any truth to these claims?

The short answer is no. There is no scientific evidence to support these claims. We’ve enlisted the help of Katelynn Maniatis, a dietitian at Sunnybrook’s Odette Cancer Centre and Program in Toronto, to help us learn more about some of the common myths and questions related to alkaline diets.

What is an alkaline diet?

An alkaline diet is one that is composed of 80% alkaline and 20% acidic foods. This diet is primarily plant-based and includes a diet rich in roots and tubers, nuts, seeds, dried beans, lentils, quinoa, spelt, soybeans, and brown rice. Other alkaline foods include green vegetables, vegetable juice and various fresh fruits.

What are some examples of acidic foods?

Foods that are considered acidic (and should be limited on an alkaline diet) are animal proteins, fish, eggs, shellfish, sugar, dairy, wheat products and gluten grains. Other foods that are highly acidic include vegetable oil, butter, margarine and processed and canned foods. You can also have a highly acidic diet if you eat large amounts of fruit, dried fruit or drink large amounts of unsweetened fruit juice, alcohol and caffeine.

Why do people think alkaline diets affect cancer cells?

Cancer cells have a very narrow pH range, between 6.5 and 7.5. This means that cancer cells can’t actually grow and spread outside of this range. The alkaline diet claims that by raising pH to an alkaline level (above 7.5), you can stop the growth of cancer cells.

Can eating an alkaline diet increase my body’s pH and stop cancer cell growth?

There is no evidence to support this claim. An alkaline diet cannot increase your body’s pH and stop cancer cell growth.


An alkaline diet may shift pH slightly after eating certain foods, but the body will always bring itself back to normal. Our bodies are extremely well tuned machines and perform many balancing acts every day to keep the internal pH between 7.35-7.45 (just slightly alkaline) at all times. Even if we eat an extremely alkaline diet, our body has natural mechanisms to bring the pH back to the normal range.

Is it dangerous to eat a high alkaline diet?

Alkaline diets leave out dairy products, poultry, eggs fish and most grains, making it difficult for people who have cancer to get the right amount of energy and protein in their diets. Alkaline diets may also cause vitamin and mineral deficiencies that can lead to a weakened immune system. The diet may be low in calcium, iron, zinc and vitamin D. It is also possible to miss out on many potential anti-cancer benefits from “acidic” foods that contain essential fatty acids, phytonutrients and fibre.

The bottom line

There is no scientific evidence to support the claim that eating an alkaline diet will reduce the spread of cancer cells, prevent cancer and help make cancer treatments work better. It is not recommended that individuals follow an alkaline diet. Instead, eat a healthy, balanced diet and speak with one of our Registered Dietitians at 416-480-5000, ext. 3438 if you have any nutritional concerns during any stage of cancer treatment and recovery.

Brought to you by the Patient & Family Education Program at the Odette Cancer Centre. This article was researched and written by Giovanni Poggenpoel, BSc, MBA Administrative Resident, Odette Cancer Centre. Content was provided by Marci Capland, RD, Amy O’Connor, MSc, RD and Katelynn Maniatis, MHSc, RD, CNSC.

About the author

Patient & Family Education, Cancer

Blog posts from Patient & Family Education team at Sunnybrook’s Odette Cancer Centre. Visit the Patient & Family Education website for more resources, workshops and information.

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