Skip to main content

In your health research online, you may have come across the idea that sugar feeds cancer, but if not, it’s time to pay attention. While some oncologists and primary care doctors may tell patients that diet has little or nothing to do with cancer, nothing could be farther from the truth. Research suggests that lifestyle and environment contribute significantly to 90-95% of cancer cases. Many people think cancer is genetic, but that’s only 5-10% of cases. [1] Having your blood sugar too high for too long promotes cancer growth. If you’ve been diagnosed with cancer or want to avoid a cancer diagnosis in the future, it’s best to limit this compound that contributes to high blood sugar levels day after day.

Sugar Feeds Cancer

The fact that sugar feeds cancer is even confirmed by the tests used to diagnose cancer. You can see in the test how much cancer loves glucose, a simple sugar. If you go to the Cancer Treatment Centers of America website, they explain how a PET scan works for identifying cancer. During a PET scan, they inject a glucose solution with a radioactive tracer into the patient. They also take computerized pictures of the organs and tissues inside the body. The cancer eats up all the glucose with the radioactive tracer, which makes the image light up where the cancer is. This is because cancer cells use more glucose than normal cells. [2]

The metabolism is different for cancer cells than normal ones. Cancer cells can take in 10 times more glucose than healthy cells. [3] Cancer cells feed off a glycolytic pathway, meaning they require sugar for energy metabolism. Instead of simply using oxygen, like healthy cells, cancer cells need glucose. Dr. Warburg, from way back in the day (1883-1970), discovered this relationship and called it the “Warburg Effect.” [4] The more glucose you take in, the more you feed cancer. You may hear from doctors that cancer patients need their strength, so sugary foods can help them get enough calories. It’s time to rethink that.

Eating sugar suppresses the immune-response process of phagocytosis. That’s when cells called phagocytes go around absorbing or eating up bacteria, dying cells, and other debris. They get rid of pathogens, which is essential. So, you don’t want to suppress your immune response, but that’s what many Americans are doing. The average American eats 32 teaspoons of sugar a day. That’s a lot! Consuming only 10 teaspoons of sugar suppresses phagocytosis by 50%. [5] Now, that’s cutting down your immune response.

You might be surprised how easily (and early in the day) sugar sneaks in. Breakfast cereals, granola bars, and fruit juices have staggering amounts of added sugar. Yes, even the whole grain cereals promoted by the American Heart Association.

Make No Mistake: The Sugar-Cancer Link is NOT Debunked

Mayo Clinic and other authorities have written that the link between sugar and cancer is a misconception. Even the American Institute for Cancer Research (AICR) says there’s no strong evidence directly linking sugar to an increased risk of cancer. Renowned cancer research centers like MD Anderson and the Memorial Sloan Kettering Cancer Center (MKCC) downplay the idea that sugar feeds cancer. [6][7] They instead point to obesity and diabetes as more important risk factors. But isn’t it possible that the same thing that leads to diabetes also leads to cancer? Here’s some research on sugar and its effects on cancer:

Study #1

A 2020 clinical trial published in the American Journal of Clinical Nutrition reported the results of the French NutriNet-Santé prospective cohort study that went from 2009 to 2019. It looked for associations between sugar and cancer for over 100,000 participants. Researchers concluded that “Total sugar intake was associated with higher overall cancer risk.” They also reported that “significant associations with cancer risk were also observed for added sugars, free sugars, sucrose, sugars from milk-based desserts, dairy products, and sugary drinks.” As a result, the researchers determined that sugar may be a modifiable risk factor for cancer prevention– especially the risk of breast cancer. [8]

Study #2

A 2021 observational study published in Clinical Nutrition looked at sugar intake and cancer based on a cohort from the PREDIMED trial. Out of 7056 individuals, there were 534 incidences of cancer and 152 cancer deaths at the 6-year follow-up. Researchers found that for every 5-gram increase in liquid sugars, the risk of cancer increased. It was dose-related for all liquid sugars. [9]

Study #3

A 2022 study published in the peer-reviewed open-access journal Cancer also explored the link between sugar and cancer. In the opening summary, the researchers were careful to mention that “excess sugar consumption can lead to development of cancer and progression of disease for those with cancer independent of the association between sugar and obesity.” This paper reviewed 24 studies published between 1946 and 2022 and used search terms concerning sugar, cancers, and the immune system. They specifically looked for links between obesity and cancer. They couldn’t find an association between obesity alone and cancer. They explain that the faulty reasoning linking sucrose and cancer only in the context of obesity was confirmed by their own animal research. [10]

Does sugar feed cancer? It certainly sounds like it. And surely more research on the sugar-cancer link is on the horizon.

Sugar Increases Cancer Risk Through Several Risk Factors

Excessive sugar intake can also impact the body in other ways that may increase cancer risk. Here are a few examples:

Obesity and Insulin Resistance

Diets high in sugar can contribute to weight gain and obesity. Obesity, especially around the middle (“visceral adiposity”), is linked to an increased risk of tumors and developing certain types of cancer, including colorectal, endometrial, and pancreatic cancers. [11][12] Visceral adiposity is often a sign of insulin resistance, where cells become less responsive to insulin. Then it becomes a vicious cycle of high blood sugar and high insulin levels. Over time, insulin resistance could affect other hormone levels in ways that could promote cancer growth. Adipose (fat) tissue itself produces hormones and signaling molecules called adipokines. When someone is obese, he or she has an imbalance in adipokine secretion, which again can contribute to cancer development. [13]


Adipokines include leptin, adiponectin, and others, which research suggests likely promote cancer by contributing to a pro-inflammatory internal environment. [13] However, high sugar consumption can also trigger inflammation, promoting cellular changes that could set the stage for cancer. It may not take long for a sugar binge to create problems. A randomized controlled trial of 29 healthy young men found that adding a sugar-sweetened beverage of 600 ml a day for only 3 weeks increased inflammatory markers. It also led to insulin resistance and weight gain. [14]

Promotion of Growth Factors

Some studies suggest that a high sugar intake could also contribute to increased levels of insulin-like growth factor-1 (IGF-1). Insulin and IGF-1 are growth-promoting hormones, and elevated levels can stimulate cell proliferation and survival while inhibiting apoptosis (programmed cell death). This increased cell activity may contribute to the development and progression of cancer. [15]

Altered Gut Microbiota

Excessive sugar consumption can disrupt the balance of gut bacteria, increasing proteobacteria and decreasing Bacteroidetes. This imbalance in the gut microbiota is more pro-inflammatory and may lead to metabolic syndrome, diabetes, and, potentially, cancer. [16] A French study published in 2015 explains that environmental factors impact the gut microbiome, creating dysbiosis and increasing the risk of cancer. [17]

Of course, cancer is a multifaceted disease. It’s not just sugar intake but a combination of genetics, environmental factors, emotional stress, and lifestyle choices that influence whether or not a person develops cancer. Maintaining a healthy diet, regular physical activity, and a healthy lifestyle are all crucial for reducing cancer risk.

Don’t Feed The Weeds

We all have cancer cells in our bodies. Those cells are like weeds in a garden. If you continue feeding the weeds, they’re going to take over the garden and strangle the good plants out. The same thing can happen with the body. If the cancer cells are kept in check, then everything’s fine. We have natural defense mechanisms, including natural killer (NK) cells, that defend the body against cancer. However, if we continue to create more cancer cells because we’re feeding them like crazy, our NK cells can’t get it under control.

Focus on cultivating a healthier environment that promotes healthy cells over cancer cells. This includes avoiding dietary sugar. Sugar-sweetened beverages like soft drinks are one of the major culprits. Take a good look at the labels sometime! You’ll see high fructose corn syrup, disguised sugars like maltose or dextrose, or horrible artificial sweeteners. Sucralose, aspartame, acesulfame K, and others come with their own set of problems. A diet soda habit contributes to dysbiosis and obesity, increasing the risk of cancer and other chronic illnesses. Aspartame, for example, has links to diabetes, Alzheimer’s, multiple sclerosis, and cancer. [18]

Avoid Added Sugar and Make Healthy Swaps

There are plenty of other options that can satisfy your sweet tooth while not feeding cancer. Instead of sugar, try stevia, monk fruit, erythritol, or xylitol. These sweeteners don’t increase your blood sugar and go through your system without creating damage. Xylitol is a great Wellness Way-approved option that also has health benefits. If giving up sugar sounds overwhelming, think how overwhelming cancer could be! Sugar feeds cancer, helping it spread. You’re either promoting cancer or supporting your body in its defense against cancer. Which would you rather do?

To learn more about The Wellness Way approach, tune in to A Different Perspective each Saturday morning LIVE to get cutting-edge training directly from Dr. Patrick Flynn. Then, set up a no-obligation health consult with one of our doctors. You can also reach out to a Wellness Way clinic near you. Get started on The Wellness Way to health today! 

Originally posted July 11, 2018. Updated April 10, 2024.


  1. Cancer is a Preventable Disease that Requires Major Lifestyle Changes – PMC (
  2. CT Scan (Cat Scan) for Cancer Detection & Treatment (
  3. The Warburg Effect: How Does it Benefit Cancer Cells? – PMC (
  4. Understanding the Warburg Effect: The Metabolic Requirements of Cell Proliferation – PMC (
  5. 5 Reasons Cancer Cells and Sugar Are Best Friends – Beat Cancer: Beat Cancer
  6. Diet & Cancer Risk | MD Anderson Cancer Center
  7. No Sugar, No Cancer? A Look at the Evidence | Memorial Sloan Kettering Cancer Center (
  8. Total and added sugar intakes, sugar types, and cancer risk: results from the prospective NutriNet-Santé cohort – PubMed (
  9. Simple sugar intake and cancer incidence, cancer mortality and all-cause mortality: A cohort study from the PREDIMED trial – PubMed (
  10. Understanding the Link between Sugar and Cancer: An Examination of the Preclinical and Clinical Evidence – PMC (
  11. Visceral Adiposity and Cancer: Role in Pathogenesis and Prognosis – PMC (
  12. Visceral obesity and incident cancer and cardiovascular disease: An integrative review of the epidemiological evidence – PubMed (
  13. Adipose tissue, obesity and adipokines: role in cancer promotion – PubMed (
  14. Low to moderate sugar-sweetened beverage consumption impairs glucose and lipid metabolism and promotes inflammation in healthy young men: a randomized controlled trial – PubMed (
  15. Sugar sweetened beverages, natural fruit juices, and cancer: what we know and what still needs to be assessed – PMC (
  16. High Intake of Sugar and the Balance between Pro- and Anti-Inflammatory Gut Bacteria – PMC (
  17. Cancer and the gut microbiota: An unexpected link – PMC (
  18. Aspartame—True or False? Narrative Review of Safety Analysis of General Use in Products – PMC (


Subscribe to our newsletter for health tips & updates.

Join the community

Disclaimer: This content is for educational purposes only. It’s not intended as a substitute for the advice provided by your Wellness Way clinic or personal physician, especially if currently taking prescription or over-the-counter medications. Pregnant women, in particular, should seek the advice of a physician before trying any herb or supplement listed on this website. Always speak with your individual clinic before adding any medication, herb, or nutritional supplement to your health protocol. Information and statements regarding dietary supplements have not been evaluated by the FDA and are not intended to diagnose, treat, cure, or prevent any disease.


  • Linda frye says:

    Thank you for this information. I have stage IV metastatic breast cancer. I have changed my diet a whole lot and continues to change it more with more exercise and diet.

    • Betsy Schroeder says:

      Hi, Linda! Thanks for sharing about your health journey. We wish you all the best! Please reach out if you need support from one of our doctors.

Leave a Reply