A new UC Irvine study may have finally uncovered how dietary fiber protects the body from sugar’s damage, and how protecting yourself starts in the gut.

Researchers at the UCI School of Medicine found that inulin, a naturally occurring fiber found in vegetables like onions, garlic and artichokes, can reshape the bacteria living in your gut to stop fructose before it hits your liver.

“We found that consuming a type of dietary fiber called inulin… changes the bacteria in the gut to promote the consumption of harmful dietary fructose,” said lead researcher Cholsoon Jang, PhD, of UCI’s Nutrient Metabolism & Disease Lab. 

The findings, published in Nature Metabolism, reveal a new level of protection offered by fiber, not just in digestion, but in how the body handles sugar at the molecular level.

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Jang and his team discovered that when people eat fructose (a common sugar in fruit and sweetened foods) gut bacteria in the small intestine can metabolize it before it reaches the liver. But without enough fiber, too much fructose “spills over,” overwhelming the liver and triggering fat buildup.

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Fructose is a sugar found in fruit that can ‘spill’ into the liver, leading to liver disease. (iStock)

By feeding gut bacteria with inulin, researchers found that the microbes essentially burn through fructose early, preventing that cascade of damage. 

Even more striking, once these bacteria were “primed” by inulin, they were able to reverse signs of fatty liver disease, reducing fat accumulation and boosting the liver’s natural antioxidants.

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Jang says the research proves not all calories are created equal.

He says their work gives “insight into how fiber protects our health from harmful nutrients like fructose.”

The Nature Metabolism study identified how specific gut bacteria metabolize sugar before it reaches the liver. (iStock)

The study focused on non-obese participants: people who might otherwise slip under the radar yet still face hidden risks from high-sugar diets. 

Jang noted that metabolic damage isn’t limited to those who are overweight. Even people who appear healthy can experience liver stress and insulin resistance if their gut microbes aren’t equipped to handle excess fructose.

“By identifying specific gut bacteria and metabolic pathways involved, our findings can guide personalized nutrition strategies,” Jang said.

Vegetables like garlic, artichokes and onions can be a good source of inulin, the helpful fiber studied by the research team. (iStock)

He added that future research will explore whether other common fibers beyond inulin can trigger similar protective effects.

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The implications stretch far beyond the lab. If certain fibers can train gut microbes to neutralize sugar before it harms the liver, it could open the door to new treatments for fatty liver disease, diabetes, obesity and even cancer.

For now, researchers explain that the findings indicate that fiber not only aids digestion but can be a defender of metabolic health.

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As Jang put it: “For example, by checking how well someone’s gut bacteria clears fructose before the body absorbs it, we can choose the right prebiotic or probiotic supplement for that person to improve results and reduce side effects.”

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Swapping your regular soda for a diet version may not be any healthier for the liver, new research suggests.

A study of UK Biobank data found that both sugary drinks and artificially sweetened ones, even those labeled zero sugar, are linked to a higher risk of liver disease.

Th findings were presented this week at United European Gastroenterology Week in Berlin, Germany.

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The study followed more than 120,000 adults over 10 years. None of them had liver disease when the research began. 

Over time, scientists tracked what the participants drank and also assessed their liver health. 

People who drank a lot of sugar-sweetened beverages (SSBs) — like soda, sweet tea or energy drinks — had about a 50% higher risk of developing a serious liver condition called metabolic dysfunction-associated steatotic liver disease (MASLD), also known as fatty liver disease not caused by alcohol.

“SSBs have long been under scrutiny, while their diet alternatives are often seen as the healthier choice,” lead author Lihe Liu, a graduate student in the Department of Gastroenterology at the First Affiliated Hospital of Soochow University, Suzhou, China, said in a press release.

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However, those who drank diet drinks — low- or non-sugar-sweetened beverages (or LNSSBs) — had an even higher risk of liver disease, at around 60%. 

That implies that switching from regular to diet soda didn’t protect their livers — and might have made things even worse.

Replacing either beverage with water reduced liver disease risk by as much as 15%, while substitution between the two types of beverages offered no risk reduction. (iStock)

People who regularly drank artificially sweetened drinks were also more likely to die from liver-related causes, the research suggested.

“Our study shows that LNSSBs were actually linked to a higher risk of MASLD, even at modest intake levels such as a single can per day,” Liu said.

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“These findings challenge the common perception that these drinks are harmless and highlight the need to reconsider their role in diet and liver health,” she added.

As to why zero-sugar might be harmful, scientists think it may have to do with how artificial sweeteners affect the body. 

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They have been shown to alter gut bacteria, increase cravings for sweets and confuse the brain’s hunger and fullness signals, for example.

Some research even suggests they may still trigger insulin spikes, something that is usually blamed on sugar.

Some research suggests that diet drinks may still trigger insulin spikes, something that is usually blamed on sugar. (iStock)

Liu said the safest approach is to limit both sugar-sweetened and artificially-sweetened drinks.

Swapping sugary or diet soda for water was shown to reduce liver disease risk by as much as 15%, while substitution between the two types of beverages offered no risk reduction.

“Water remains the best choice, as it removes the metabolic burden and prevents fat accumulation in the liver, whilst hydrating the body,” the researcher noted.

Liver disease is already one of the fastest-growing health problems worldwide, affecting approximately 4.5 million U.S. adults, according to CDC data.

As the full study had not yet been published in a peer-reviewed journal, potential limitations of the study were not available.

“Water remains the best choice, as it removes the metabolic burden and prevents fat accumulation in the liver, whilst hydrating the body,” the researcher said. (iStock)

Some experts, however, pointed out that the beverage consumption was self-reported and may have some inaccuracies. The observational study also identifies an association, but does not prove that the beverages caused liver issues.

The Calorie Control Council, the international association representing the low- and reduced-calorie food and beverage industry, echoed these potential limitations.

“The public should demand science-bas‎ed findings, ‎especially those intended to inform their food and beverage choices,” said Carla Saunders, president of the Calorie Control Council in Washington, D.C., in a statement to Fox News Digital. “One such peer-‎reviewed long-term clinical trial published in the International Journal of Obesity proved that ‎low- and no calorie sweetened beverages are just as effective as water in terms of safety ‎and efficacy.”

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Fox News Digital reached out to the American Beverage Association and to the study researchers requesting comment.