Biopsychology of Sugar, Cells, and Cancer


Physical & Sexual Health
hero symbol

 28% of Americans believe sugar directly feeds cancer.

We interviewed Melissa Phelps, RD, CSO to learn more. Melissa Phelps is a registered dietitian and certified specialist in oncology. She received her Bachelor’s degree in Nutritional Sciences from Rutgers University and completed the Sodexo NY/Philadelphia Dietetic Internship with a medical nutrition therapy emphasis.

According to the 2017 AICR Cancer Risk Awareness Survey, which included 1,004 adult respondents in the U.S., 28% of Americans believe sugar directly feeds cancer. However, research shows that sugar is only indirectly linked to cancer since too much sugar in the diet can lead to excess body fat and unintended weight gain. Per the CDC, being overweight or obese increases the risk for 13 different cancers, including colon and rectal cancer. There are several reasons why excess body fat, particularly belly fat, can increase the risk for cancer.

To understand the biophysiology, the basic building block of sugar is glucose. All of our cells need glucose to survive.

In fact, when blood glucose is too low, you could pass out. The human body has unique pathways to convert non-glucose sources of energy into glucose to prevent you from passing out. Therefore, cutting out grains and fruits and any other sources of food that turn into glucose (sugar) will not necessarily be helpful, and, in fact, may be harmful.

What should you do?

With regards to a cancer-protective diet, the quality and quantity of carbohydrate in the diet is important. Complex carbohydrate is preferable to simple carbohydrate for general, overall health.

Simple Carbohydrate

Simple carbohydrate is found in foods that are processed. For grains, during processing, the outer layer of the grain (the bran layer) is removed, stripping the grain of most of its dietary fiber. Foods that are high in simple carbohydrate due to this processing include: white rice, white pasta, white bread, and any other grain product where the first ingredient listed is “wheat flour” (even if the wheat flour is noted to be enriched, unbleached or bleached).

Other dietary sources of simple carbohydrate include sugar-sweetened beverages, fruit juices, and sugary desserts. Too much simple carbohydrate in the diet can cause significant blood sugar spikes, which can increase risk for diabetes. When consumed in excess, it can also contribute to unintended weight gain.

Complex Carbohydrate

Complex carbohydrate is high in dietary fiber. Foods rich in complex carbohydrate can prevent constipation and induce satiety (the feeling of fullness and suppression of hunger after eating). In other words, complex carbohydrate makes you feel fuller and satisfied longer, decreasing the likelihood of overeating.

To increase your intake of complex carbohydrate and decrease your intake of simple carbohydrate, choose whole grains, such as brown rice, unsweetened oatmeal, bean-based or whole wheat pasta, whole wheat bread, faro, and barely.

With foods derived from wheat, the key word is “whole” in the ingredient list, such as “whole wheat” or “whole grain”. A good rule of thumb is to make at least half grain intake each day whole grains. Avoid processed grains like white rice, white pasta, and white pasta. Avoid cereals made from processed grains and cereals with added sugar. Limit or avoid sugar-sweetened beverages and fruit juices. Choose a variety of fruits in the diet, instead of fruit juice.  

Portion sizes

Portion sizes are also important. For meals, limit grains and starchy vegetables to one-quarter of your food plate, rather than being the main part of your meal. Fill half your plate with fruits and non-starchy vegetables and the last quarter with lean protein (such as baked chicken or fish) to satisfy recommendations for a well-balanced meal. If you are having a sugary snack, like cookies, stick with the suggested serving size on the nutrition label.

It is okay to have some foods high in simple carbohydrate as long as you are practicing portion control.

Get the latest issue of Beyond Blue!

Food. We can't live without it, but for many in the colorectal cancer community, it's hard to live with it. Yet as doctors, nutritionists, and research data all say: Diet and nutrition play an essential role in cancer prevention and treatment. Food is a topic we can't ignore.