- A new study suggests that eating a high-fructose diet can cause inflammation of the immune system.
- This process produces more reactive molecules, which are also associated with inflammation.
- Inflammation can damage cells and tissues and cause disease.
A new study suggests that a diet high in sugar fructose may prevent the immune system from functioning properly.
Fructose is a natural sugar that is present in fruits, honey and certain vegetables, such as asparagus and pumpkin. These types of fructose sugars can contribute to a healthy diet, as fruits and vegetables often contain less sugar than processed foods sweetened with sugar.
High fructose corn syrup (HFCS), on the other hand, is a manufactured sweetener made from corn starch. In the latter part of the last century, many manufacturers of processed foods and soft drinks, mainly in the United States, quickly began to choose HFCS to sweeten their products due to its low cost.
Health experts disagree about whether HFCS is more harmful than other sugars.
The Food and Drug Administration (FDA) declares that it has seen no evidence that foods that contain HFCS are less safe than foods that incorporate other sweeteners. The 2020–2025 Dietary Guidelines for Americans also do not highlight HFCS, recommending that people limit consumption of all added sugars.
Even so, research has consistently shown links between consuming large amounts of HFCS and various conditions, such as obesity, diabetes and non-alcoholic fatty liver disease.
One problem with HFCS is that it is present in a number of processed foods, including some that people may not expect, such as frozen pizza and salad dressing.
A 2019 study found that culturing human dendritic cells – which play a role in the immune system – in fructose led to an increase in inflammation. However, the researchers did not investigate the metabolic mechanism behind this occurrence.
For the new study, which appears in the journal Nature Communications, researchers from the School of Medicine at Swansea University, the University of Bristol and the Francis Crick Institute in London, all in the UK, examined how human and mouse cells responded to fructose exposure.
Their work indicates that a diet rich in fructose can impair the functioning of the immune system.
The researchers found that fructose causes inflammation of the immune system. This process, in turn, produces more reactive molecules, which are associated with inflammation.
Specifically, this sugar adjusts cellular metabolic pathways to promote the production of more reactive inflammatory cytokines.
As the authors note in their article, “fructose reprograms cellular metabolic pathways to favor glutaminolysis and oxidative metabolism, which are necessary to support increased production of inflammatory cytokines”.
This type of inflammation can damage cells and tissues, contribute to organs and systems not working well and lead to disease.
“Our study is exciting because it takes us a step further to understand why some diets can lead to health problems,” said Dr. Emma Vincent, study author and researcher at Bristol Medical School.
The research also clarifies how fructose can be associated with obesity, since inflammation is usually associated with this condition.
In addition, the researchers found that fructose leaves cells vulnerable to “new metabolic challenges”. This finding suggests that individuals on diets high in fructose may be at increased risk of poor results when fighting infections or facing other “metabolically challenging environments”.
In the study, the researchers emphasized that it is especially important to understand the effects of fructose on cell function, as humans have increased consumption of HFCS worldwide.
The researchers hope that their findings will lead to new studies that could help scientists develop treatments for a variety of conditions, including cancer and infectious diseases.
“Research on the different components of our diet can help us understand what can contribute to inflammation and disease and what can be better used to improve health and well-being,” said Dr. Nick Jones, one of the study authors and immunologist at Swansea University Medical School.