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Ketogenic Diets, Sugar, & Cancer

Posted: November 10, 2021



By: Daniel Rodgers, RD

During my time as an Oncology Dietician/Nutritionist, I have received many questions from our patients with cancer diagnoses regarding Ketogenic diets along with the potential roll of sugar in cancer. I would like to take some time today to address both topics.


Ketogenic Diet:

There has been growing interest in the use of Ketogenic diets as complimentary support to proven cancer treatments. 

A Ketogenic Diet is a very high-fat, very low-carb, adequate protein diet that promotes ketosisKetosis refers to a state when dietary carbohydrate is restricted and replaced with dietary fat.  The body then produces ketones (by-products of fat metabolism) which can be used as an alternate primary fuel source in the body.  High levels of ketones in the body equals a state of ketosis.

Absent dietary carbohydrates, the body can and will continue to make glucose (sugar) from protein we eat or from protein scavenged from muscle tissue.  With a proper Ketogenic diet, circulating glucose levels are going to be significantly lower but still present.

Some studies have shown potential benefits of ketosis in certain forms of cancer by possibly enhancing effects of chemotherapy/radiation. Other studies have shown potential pro-tumor growth in certain forms of cancer with high levels of ketones

The lack of robust controlled studies paired with the variable outcomes in current research (some negative, some positive) leaves the question of when or if a Ketogenic diet is going to be either helpful or harmful in cancer treatment.  

Starting a Ketogenic diet with just any cancer diagnosis is not warranted at this time based on available data.   A medical professional specifically trained in cancer treatment can help determine if use of a Ketogenic diet is an appropriate compliment to proven treatments. 


Sugar, Cancer, and Health:

A topic that pairs well with this discussion is the idea of “sugar feeding cancer” and the overall impact of excess sugar intake on our health.

Cancer cells, like most healthy cells, use glucose (the most basic form of sugar) for energy.  Based on where the cancerous cells are located, those cells may utilize more or less glucose as a primary fuel source.  This does not automatically mean sugar will promote or accelerate cancer growth.

The vast majority of studies showing a potential link between sugar intake and cancer risk have clearly pointed a finger at excess simple sugars from refined and concentrated sources.  Think: soft drinks, juices, candy, cookies, ice cream, pastries, etc.  High intakes of these foods are associated with increases in body weight and inflammation, both of which are certainly associated with increased cancer risk.

Is avoiding the “apple a day” going to prevent or slow cancer growth?  Highly unlikely.  Is cutting out the daily soft drink or sugary coffee drink likely to improve your overall health?  Absolutely.

Without knowing if a specific form of cancer will respond to any specific diet, avoiding certain foods that are generally considered healthy may be more detrimental than helpful.

Arbitrarily, eliminating entire food groups can create its own set of problems especially if someone is experiencing common side effects of cancer treatment like nausea, food intolerances, and changes in taste.  Narrowing food options when appetite is already impacted can lead to even more stress, food aversions, and poor nutrition overall.

It is very easy to “major in the minors” and focus on minute details when we need to step back, look at the big picture, and focus on total body health first.  People undergoing cancer treatment often suffer from nausea, lack of appetite, dry mouth, and taste changes.  Just maintaining adequate nutrition is often our primary goal.  Any diet that is complex and requires major food restrictions can worsen quality of life and overall nutrition while offering little or no proven benefit.  Team up with your healthcare providers to find out what is best for you

If you would like to schedule a consult with me to discuss your individualized nutrition needs and concerns, please contact Cancer Care Northwest at (509) 288-1000.


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