What Sugars Cause Inflammation in the Body?

October 21, 2025 •

3 min read

According to a 2024 review, high consumption of added sugars like sucrose and fructose is linked to increased inflammation, with some studies showing a significant rise in inflammatory markers like C-reactive protein (CRP) shortly after intake. This article explores what sugars cause inflammation in the body, detailing how they trigger an immune response and contribute to chronic disease.

Quick Summary

Excessive intake of refined and added sugars, particularly fructose and sucrose, can trigger systemic inflammation. Key mechanisms include the promotion of pro-inflammatory cytokines, oxidative stress, and gut microbiome dysbiosis. Understanding the different types of sugar and their metabolic pathways is crucial for managing inflammation and supporting overall health.

Key Points

Fructose Overload: Excess dietary fructose overwhelms the liver, which converts it into fat and increases uric acid, both of which can trigger inflammatory responses.
Blood Sugar Spikes: High-glycemic sugars like glucose cause rapid blood sugar and insulin spikes, which can lead to insulin resistance and chronic inflammation.
AGE Formation: When sugar levels are high, harmful Advanced Glycation End-products (AGEs) form, promoting oxidative stress and inflammation throughout the body.
Gut Dysbiosis: Added sugars disrupt the gut microbiome balance, potentially increasing intestinal permeability and causing a systemic inflammatory reaction.
Distinguish Sugar Types: The key to managing inflammation is distinguishing between natural sugars in whole foods and the added, processed sugars that are the primary inflammatory culprits.
Read Labels: Learning to identify added sugars, which go by many different names, is critical for making informed dietary decisions to reduce inflammation.

The Pro-Inflammatory Effect of Added Sugars

Refined and added sugars are the primary culprits behind diet-induced inflammation. Unlike sugars naturally found in whole foods like fruits, which are accompanied by fiber and nutrients that slow absorption, added sugars are rapidly absorbed and can overwhelm the body's metabolic pathways. This rapid intake is what triggers a cascade of pro-inflammatory responses.

Fructose: The Liver's Overload

Excessive fructose consumption is particularly problematic because it is almost exclusively metabolized by the liver. The liver can only process a certain amount of fructose at a time; when it is overloaded, the excess is converted into fat. This leads to several inflammatory consequences:

Free Fatty Acid Production: The liver's processing of excess fructose increases the production of free fatty acids, which can trigger inflammatory pathways. This can contribute to non-alcoholic fatty liver disease (NAFLD), a condition characterized by fat accumulation and inflammation in the liver.
Uric Acid Release: A byproduct of fructose metabolism is uric acid. High levels of uric acid can trigger inflammation by activating the NLRP3 inflammasome, a multiprotein complex that plays a crucial role in immune response.

Glucose and the Glycemic Index

While glucose is the body's main energy source, an overabundance can also fuel inflammation. Refined carbohydrates and simple sugars cause rapid spikes in blood sugar levels, measured by their high glycemic index. This triggers the pancreas to release high levels of insulin. Over time, high blood sugar and insulin can lead to:

Insulin Resistance: Constant high insulin levels can lead to insulin resistance, a state where cells become less responsive to insulin. This metabolic dysfunction is strongly associated with chronic, low-grade inflammation.
Advanced Glycation End-products (AGEs): Excess sugar in the bloodstream can react with proteins and fats to form AGEs. These compounds are highly inflammatory and are linked to oxidative stress, which further damages cells and promotes inflammation.

The Gut Microbiome and Inflammation

High-sugar diets disrupt the delicate balance of the gut microbiome, a community of trillions of microorganisms that play a vital role in health. This disruption, known as dysbiosis, is a key driver of inflammation.

Leaky Gut: High sugar intake can increase the permeability of the intestinal wall, a condition sometimes called "leaky gut". This allows bacteria and their toxins to leak into the bloodstream, triggering a systemic inflammatory response.
Altered Bacterial Balance: Inflammatory sugars can alter the composition of gut bacteria, favoring pro-inflammatory species and reducing the population of beneficial bacteria that produce anti-inflammatory short-chain fatty acids.

How to Identify and Limit Inflammatory Sugars

To reduce sugar-induced inflammation, it is vital to recognize the many different names for added sugar on food labels. Reading ingredient lists is essential for making informed dietary choices. Many processed foods, sweetened beverages, and baked goods are major sources of these inflammatory culprits.

Common Names for Added Sugars to Watch For:

Fructose
Sucrose
Glucose
High-fructose corn syrup (HFCS)
Dextrose
Maltose
Corn sugar
Cane sugar
Honey, maple syrup, and agave syrup (while natural, are still added sugars when processed and put into other foods)

Comparison Table: Natural vs. Added Sugars


Feature	Natural Sugars (in Whole Foods)	Added Sugars (in Processed Foods)
Source	Fruits, vegetables, dairy	Processed foods, sweets, sugary drinks
Metabolism	Slow and steady due to fiber and other nutrients	Rapid absorption, leading to blood sugar spikes
Associated Nutrients	Accompanied by fiber, vitamins, and antioxidants	None; provides only empty calories
Impact on Insulin	Mild, steady insulin response	Large, rapid insulin spike
Risk of Inflammation	Low; whole foods often contain anti-inflammatory compounds	High; promotes chronic, low-grade inflammation
Metabolic Health	Supports healthy metabolic function	Linked to insulin resistance, weight gain, and metabolic syndrome

Conclusion: Making Smarter Choices for Less Inflammation

Excessive intake of refined and added sugars, specifically fructose and sucrose, is a major dietary driver of chronic inflammation. This inflammation is initiated through multiple pathways, including the overtaxing of the liver, rapid blood sugar fluctuations, the formation of damaging AGEs, and the disruption of the gut microbiome. The good news is that by focusing on whole foods rich in natural sugars, fiber, and antioxidants, and by actively reducing your consumption of processed and sugary products, you can significantly mitigate sugar's inflammatory effects on your body. Cultivating a diet rich in fruits, vegetables, and whole grains and reading food labels carefully are powerful steps toward managing inflammation and promoting long-term health. For more information on dietary choices, consult resources like the Arthritis Foundation.

Frequently Asked Questions

You should be most concerned about added and refined sugars, particularly fructose (often found in high-fructose corn syrup) and sucrose (table sugar), which are linked to systemic inflammation when consumed in excess.

The liver is the primary organ that metabolizes fructose. When you consume too much, the liver gets overwhelmed, turning the excess into fat and producing high levels of uric acid, both of which trigger inflammatory pathways.

No, the sugar naturally present in whole fruits is not linked to inflammation. The fiber and other nutrients in fruit slow down sugar absorption, preventing the rapid blood sugar spikes caused by added sugars.

Yes, research indicates that high sugar intake can alter the gut microbiome and increase intestinal permeability, allowing inflammatory substances to leak into the bloodstream, a phenomenon associated with "leaky gut".

Advanced Glycation End-products (AGEs) are compounds formed when excess sugar in the bloodstream binds to proteins and fats. They are highly inflammatory and contribute to oxidative stress, which can damage tissues over time.

When consumed in processed products, natural sweeteners like honey, agave, and maple syrup are still considered added sugars. It is their overconsumption in processed forms, not their natural state, that contributes to inflammatory effects.

Reducing or eliminating processed foods and sugary drinks, reading food labels to identify hidden sugars, and increasing your intake of whole foods like fruits, vegetables, nuts, and healthy fats are effective strategies.