Sugar and the immune system

By Erin Cazel, guest contributor

This article was originally published in November 2022

woman cutting apples

Whether you take pride in a top-secret family cookie recipe or enjoy experimenting with new desserts, sharing sweet treats is a favorite tradition in the festive lineup of holiday parties and family gatherings. Unfortunately, we often share sickness as well at this time of year, with seasonal reports of colds and other illnesses spreading predictably among communities.

Many environmental and individual factors influence whether someone gets sick, including the amount of time spent in close contact, the ventilation of the space, the virulence of the specific viral or bacterial strain, and the susceptibility of the individual. But what if sugar adds to that equation? Could our uptick in eating sweets also contribute to a higher risk of getting sick? 

We know that consistent high sugar consumption over the long term can lead to the development of chronic diseases such as type 2 diabetes, metabolic syndrome and cardiovascular disease. Emerging research shows that those extra seasonal servings of your aunt’s pumpkin pie may also increase your odds of being under the weather short-term. The reason for this has to do with a molecular process called glycation. But let’s zoom out for a moment before we focus on the molecular level. 

Your body is a very busy place: each body system responds to and influences every other system through an intricate web of communication. Their collective goal is to make moment-by-moment, fine-tuned adjustments in order to stabilize your body in the midst of an ever-changing environment. In the immune system, specialized dendritic cells are stationed at key points of entry throughout the body, such as your skin, and the linings of your nose, lungs, stomach and intestines. Dendritic cells sample the foreign substances they encounter and present pieces of those substances (called antigens) to other types of immune cells. These immune cells respond by increasing their numbers and building up an arsenal of antibodies to target the foreign intruders. Dendritic cells therefore are key players that initiate and strengthen your body’s immune defense system. 

As you eat foods that are high in sugar, sticky sugar molecules enter the body. Some of these sugar molecules bump into and stick onto proteins on the surface of the dendritic cells. This unintentional process is known as glycation and impairs the ability of dendritic cells to either sample foreign substances, present the antigens to other immune cells, or both. Decreased function of dendritic cells is what researchers believe causes the immune suppression associated with high sugar consumption. 

Fortunately, your amazing body has built-in mechanisms for removing these unwanted sugar molecules. But reversing glycation takes time, and the immune system can remain suppressed for several hours after consuming high-sugar treats. During this time, you may be more susceptible to the opportunistic bacteria and viruses lurking at the holiday buffet. 

But wait! Before you throw up your hands (or throw out this paper) and despair of participating in your neighborhood cookie exchange, there are some simple ways you can mitigate the impact of sugar. 

  • Moderate sugar intake. The higher the influx of sugar, the more opportunity for glycation, and the longer it will take your immune system to recover. Let yourself luxuriate in the sweet experience: notice the colors and aroma, the texture of the bite in your mouth, and the complexity of the mingled flavors. When you gift yourself the time and space to savor your dessert, you may find your sweet tooth more readily satiated than if you were to quickly consume multiple servings. 
  • Reduce or replace sugars in your recipes. It’s possible to simply reduce the amount of sugar used in most recipes without dramatically affecting its taste or structure. If you’re feeling more experimental, unsweetened applesauce, puréed bananas, or softened and puréed medjool dates can be used to sweeten baked treats. The sugars naturally occurring in these whole foods are bound with fibers and absorbed more slowly through the digestive tract. This slows the rate of sugar exposure to dendritic cells, reducing the rate of glycation. Fruits also contain vitamins and minerals that actually support your immune response. In contrast, refined and processed sugars such as cane sugar, agave nectar or high fructose corn syrup are stripped of fiber and other supportive nutrients, and are absorbed rapidly into the body, resulting in a spike in blood sugar. Maple syrup, raw honey and coconut sugar are popularly used as replacements for refined sugars. These sweeteners are minimally processed and do contain some beneficial vitamins and minerals. However, because they lack the fiber of whole food options, they can also result in a blood sugar spike and are best consumed in moderation. Similarly, the sugars contained in refined grains such as white flour are more rapidly absorbed than those in whole grains. Try replacing a portion of the white flour in your holiday baked goods with 100% whole grain flour. Whole wheat is a great standby, but other whole grain options include teff, sorghum and rye flours. 
  • Add a healthy immunity boost. We nourish our bodies not by what we restrict but through what we consume. Vitamins C, E, A and folate are particularly important for supporting immune cell growth and function, as are the minerals zinc and magnesium. Good sources of these nutrients include brightly colored whole foods (such as sweet potatoes, oranges, strawberries, red bell peppers, dark leafy greens), nuts, seeds and legumes. Spices such as turmeric and ginger contain phytonutrients that help reduce inflammation and encourage immune health. Consider the balance of your whole plate at the holiday buffet and think creatively about adding some immune-supporting seeds or spices to dessert time. Perhaps it’s a sprinkle of hemp seeds mixed into your baked treat, or maybe you pair your dessert with a turmeric-infused tea. 

Each person processes sugar differently depending on a multitude of factors that may shift seasonally, and even from day to day. Keep in tune with your body to gauge your own response in the moment. Whatever way you slice it, may you delight in the sweetness of connection this season, and may your celebrations be nourishing in body, spirit and soul. Who knows, the experimental dessert you test out this year may become the cherished family recipe for years to come. 


Erin Cazel is pursuing a master’s in Nutrition at Bastyr University. Radical hospitality is Erin’s life passion—she loves gathering community around a table filled with food and conversation, and cares deeply about using foods to nurture the body, heart and mind.

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