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Sugar and Cancer: The Truth

Humans need sugar, but not too much!

Sugar is sweet, full of calories, and a very simple form of a carbohydrate that is quite easily digested and used efficiently by the body for it’s important metabolic needs.  Too much, however, is unnecessary.  Yet in todays world, getting too much is becoming too easy. 

Sugar is hidden within numerous packaged food products to promote shelf life and increase the bliss felt after eating something so sweet.  Sugar is delicious.  From an evolutionary perspective, we have an innate taste for sugar, that proves full of pleasure.  At times of famine, this calorie rich nutrient was essential for survival, and due to our biological makeup, we still feel this need.  Sugar causes the chemical called dopamine to be released in the brain and can be addictive. 

Maintaining normal blood sugar levels is critical for muscular energy and to sustain a healthy brain.  If you are active, having a good supply of stored energy, called glycogen, is important for the muscles to tap into.  Sugar makes up this energy supply within our skeletal muscles and liver.  When it’s depleted, our bodies will find alternate pathways to create sugar through the breakdown of our own fats and proteins in our muscles.  To prevent this, eating carbs are necessary.


Simple or Complex?

Carbohydrates come in two “flavors”: simple and complex.

Simple carbohydrates are found in foods like white rice, cookies, and candies. They tend to have a sweeter taste and are rapidly absorbed into the bloodstream after being consumed, causing sharp spikes in insulin.  They are best eaten in moderation, or just prior to moderate to intense work outs lasting longer than 30 minutes.

Complex carbohydrates include whole grains, vegetables, and fruits, and they are higher in fiber, take longer to digest, and include vitamins and minerals essential to your overall health.  Insulin spikes are slower and steadier due to the progressive absorption by the intestines.  The essential fibers help to feed the healthy bacteria in the large intestine, and promote satiety to help avoid excessive calorie intake.  These should constitute the majority of the 45-60% of carbohydrates that are eaten per day within a persons caloric needs.  


The research behind cancer and sugar

When it comes to the possible relationship between sugar and cancer, the research is interesting.  Population based studies have shown that people with the highest sugar consumption have the highest prevalence of cancer.  But is there more to this?

Since sugar is calorically dense and can easily cause weight gain, and obesity is correlated with cancer due to a myriad of reasons that include increased systemic inflammation, there could be a possible link as a result[i].

Researchers have been investigating several mechanisms that may uncover a potential connection behind sugar and cancer.  Lets explore some of the more promising theories.



One of the relationships between sugar and cancer has to do with Advanced Glycation End Products or AGES. AGES are highly unstable molecules. They are linked to oxidation and inflammation, creating unstable cellular environments, possibly conducive to the propagation of cancer cells.  We all form AGES as a normal part of aging, but since simple sugars serve as the backbone of AGE molecules, people who consume more simple sugars in their diets may have higher rates of AGE formation.  


Insulin resistance

When a cell is insulin resistant, the insulin transporter does not work to allow insulin to latch onto a cell to transport sugar from the blood into storage.  Thus, glucose remains in the blood, driving the body to release even more insulin. This is insulin resistance, and it’s this propogation that is detrimental to health, and leads to diabetes, and now perhaps cancer. 

Insulin resistance has a number of inflammatory implications in the body which include high levels of growth factors, adipokines, and reactive oxygen species that are ultimately creating a pro-inflammatory state associated with the initiation and proliferation of cancer cells.


Cancers Possibly Associated with Sugar

  1. Breast Cancer – In the case of breast cancer, the relationship seems to manifest through hormonal changes. There only seems to be a relationship with estrogen receptor-positive breast cancer.  Insulin and insulin growth factor-1 (IGF-1) associated with sugar intake lead to elevated levels of estrogen and other hormones that may contribute to tumor progression. Once diagnosed, insulin resistance may lead to a worse prognosis and a more challenging journey.  Since genetics in large part determines the risk for breast cancer, those who are genetically inclined and tend to have more IGF -1 in the blood may be at the greatest risk.
  2. Pancreatic cancer – It is unknown if insulin resistance causes pancreatic cancer, or vice versa.  A 2017 review article determined that diabetes increased risk of pancreatic cancer[ii].
  3. Lung, liver, and endometrial cancer – Recently, a certain common tumor type of lung cancer called squamous cell carcinoma has been shown to be made up of high levels of GLUT1 receptors, which have a vital connection to sugar!  Glut 1 is a main transporter of glucose into the cell, essentially the gatekeeper that allows sugar to enter.  It was discovered that these particular tumor types can survive and grow more readily, within a healthy environment of sugar, essentially feeding on the sweet stuff as it’s available.  This finding leads the researchers to assume that a lower sugar diet will help to slow the progression of this tumor, and may in fact have a direct association with sugar[iii].  


Take Home Advice

Research continues to solve the riddle of cancer, and in the case of sugar, we know too much is bad for your health, but the direct cause of cancer by sugar is still under investigation and no sincere claims can be made just yet.  However, the research is compelling, and it may be in the best interest to limit your sugar intake. 

Keep it complex! Focus your intake on the nutrient rich complex carbohydrates that include whole grains, fruits, vegetables and beans and legumes.  And if you will be having sweet treats, cereal or any other more simple form of carbohydrate, take control of your health and eat them strategically.  Consume in the beginning of the day or prior to more intense workouts, so that your body can use the sugar as fuel instead of storing it as sugar and spiking that insulin unnecessarily high.

And focus on the label.  Since the new and improved nutrition facts label is rolling into the market, the “added sugars” will be listed as a subcategory of “sugars” which will help to clarify which type of sugar is most prevalent in the food you are eating.  Keep total added sugars around 50grams or less for the day, which turns out to be about 10% or less of your total calories.  


[i] Zheng Y, Manson JE, Yuan C, et al. Associations of weight gain from early to middle adulthood with major health outcomes later in life. JAMA. 2017;318(3):255-269
[ii] Shafqet M., Sharzehi K. Diabetes and the Pancreatobiliary Diseases. (2017) Curr Treat Options Gastroenterol. 15(4): 508-519
[iii] Goodwin, J; Neugent ML et al. The distinct metabolic phenotype of lung squamous cell carcinoma defines selective vulnerability to glycolytic inhibition. (2017). Nat Commun. 8:15503
Hillary Sachs, MS, RD, CSO, CDN

Hillary is a Registered Dietitian and Board Certified Specialist in Oncology Nutrition (CSO). She received her BS in Nutritional Sciences at Cornell University and MS in Clinical Nutrition at New York University, and completed her dietetic internship at the James J. Peters Bronx VA Medical Center. Hillary works as an outpatient dietitian at the North Shore-LIJ’s Cancer Institute, where she counsels patients and their families before, during and after cancer treatment. Additionally, Hillary counsels clients on nutrition through her private practice, Recipe for Health, L.L.C., and has been invited to present at several nutrition-related events including the Breast Cancer Update Symposium at North Shore-LIJ (2013) and Adelphi University’s Farm to Table lecture (2014). Hillary strives to translate the science behind health, nutrition and prevention into practical and easy-to-follow recommendations.

    1. Thanks for the feedback! It is a really interesting topic that I think we learn more about through further research as time elapses.

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