The practice of reaching for a comforting sugary drink or treat when feeling unwell is common. People often associate simple sugars, from flat soda to honey-sweetened tea, with feeling better or having the energy to fight off illness. Determining if this habit is truly beneficial or simply psychological comfort requires examining the body’s biology during active infection. This exploration covers the metabolic demands of sickness and the cellular effects of sugar consumption on the immune response.
The Body’s Increased Energy Demand During Illness
Fighting off an illness is a metabolically expensive process that significantly increases the body’s energy requirements. When the immune system activates, the body releases stress hormones, such as cortisol, which prompt the liver to increase glucose production and raise blood sugar levels. This natural response ensures that energy is readily available to the cells that need it most.
Immune cells, including lymphocytes and phagocytes, undergo a rapid metabolic shift to meet the demands of proliferation and function. T cells dramatically increase their uptake of glucose to fuel glycolysis, which provides both energy and the building blocks necessary for rapid cell division. A steady supply of fuel is necessary to sustain the immune response and the general metabolic rate, which is often elevated by symptoms like fever and inflammation.
How High Sugar Consumption Affects Immune Cell Function
While the immune system requires glucose, consuming large amounts of refined sugar at once can have a temporary, negative impact on immune function. A rapid spike in blood glucose levels following the consumption of simple carbohydrates can inhibit the efficiency of neutrophils, a type of white blood cell. Neutrophils are a primary line of defense, responsible for engulfing and destroying invading bacteria through phagocytosis.
Studies show that high sugar intake can reduce the ability of neutrophils to perform phagocytosis, with the suppressive effect potentially lasting for several hours. Elevated blood sugar also contributes to the production of inflammatory markers, which can exacerbate the existing inflammatory state caused by the infection. An excessive and sudden influx of sugar can hinder the immediate ability of the immune system to fight pathogens.
Hydration and Electrolytes
Often, the perceived benefit of a sugary drink when sick is the liquid and electrolyte content, not the sugar itself. Hydration is paramount during illness, especially if a fever is present or if the person is experiencing fluid loss from vomiting or diarrhea. Dehydration can quickly worsen symptoms and slow recovery.
A small amount of glucose is integral to effective rehydration by activating the Sodium-Glucose Co-Transporter 1 (SGLT1) mechanism in the small intestine. This mechanism requires both sodium and glucose to efficiently pull water into the bloodstream, which is the biological principle behind oral rehydration solutions (ORS). However, a beverage with an excessively high sugar concentration, such as standard soda, can be counterproductive. High sugar content creates a hypertonic solution in the gut, which can osmotically draw water out of the body’s cells and into the intestine. This effect can delay fluid absorption and may even worsen gastrointestinal discomfort.
Practical Guidance for Sugars When You Are Sick
The nuanced role of sugar during illness suggests that the type and amount of carbohydrate consumed are the most important factors. For sustained energy to support the immune system, the focus should be on complex carbohydrates and whole foods that release glucose slowly into the bloodstream. This approach provides the necessary fuel without creating sharp blood glucose spikes that can temporarily impair immune cell function.
If a person is unable to tolerate solid food, consuming easily digestible sources of carbohydrates is necessary to prevent energy depletion. Small, controlled amounts of natural sugars from sources like diluted fruit juice or unsweetened applesauce are preferable to maintain stable blood sugar levels. Refined white sugar, high-fructose corn syrup, and highly processed sweets should be limited due to their potential to suppress the immune response and contribute to inflammation.
For rehydration, it is best to choose specific oral rehydration solutions or dilute sugary liquids to ensure the optimal glucose-to-sodium ratio for efficient water absorption. A small teaspoon of honey in tea may help soothe a cough, but it should not be viewed as a replacement for nutrient-dense foods or balanced hydration.