Another potential warning sign for diets high in ultra-processed foods: It can lead to arthritis.
Researchers at the University of California, San Francisco, studied the MRI scans of the thighs of 666 participants in the National Institutes of Health’s Osteoarthritis Initiative and found those who had diets higher in ultra-processed foods – mass-produced breads, cereals, prepackaged meals and sweetened drinks – were likely to have more fat in their thigh muscles.
Intramuscular fat in the thigh can raise the risk of osteoarthritis in the knee, which is a major health concern, researchers said.
These patients had not yet developed osteoarthritis, but the researchers found that the more ultra-processed foods people said they ate, the more intramuscular fat they had in their thigh muscles, regardless of how many calories they consumed.
“In an adult population at risk for but without knee or hip osteoarthritis, consuming ultra-processed foods is linked to increased fat within the thigh muscles,” said the study’s author Dr. Zehra Akkaya, a researcher and former Fulbright Scholar in the UCSF department of radiology and biomedical imaging in a press release about the research, which was presented earlier this month at the annual meeting of the Radiological Society of North America.
Participants in this study were age 60, on average, and were overweight with a a body mass index (BMI) of 27. About 40% of the foods they had eaten in the past year were ultra-processed foods, she said.
This study suggests how the consumption of ultra-processed food impacts the body’s muscles. Ultra-processed foods led to increased fat in the thighs, regardless of a person’s exercise regimen or calorie intake, researchers found.
“These findings held true regardless of dietary energy content, BMI, sociodemographic factors or physical activity levels,” Akkaya said.
The UCSF study is relatively small, but is the first one using magnetic resonance imaging (MRIs) to investigate the relationship between skeletal muscle quality and the diet, Akkaya said.
But previous studies have also suggested the health risks of ultra-processed foods. A June 2024 study in the journal Neurology looked at the health data of more than 14,000 participants and found an increased intake of ultra-processed foods by just 10% was linked to a greater risk of cognitive impairment and strokes.
A 2023 study suggested women who consumed a lot of ultra-processed food and drinks could be at a higher risk of developing depression.
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What are ultra-processed foods?
Ultra-processed foods are often ready-to-eat foods produced by high-pressure shaping or chemical alteration to appear a certain way or have a longer shelf life. Low in fiber, protein and vitamins, they are usually high in sugar, fat and salt, and often contain artificial colors and additives.
Examples, according to the Harvard Medical School, include snacks such as potato chips, industrial breads and pastries, candy packaged sweets and candy, sugar-sweetened and diet sodas, breakfast cereals, margarines and spreads, instant noodles and soups, frozen pizzas and dinners, ready-to-eat meals and processed meats such as hot dogs and bologna.
These convenient foods usually contain sugar, fat, salt and carbohydrates which affect the brain’s reward system and make it hard to stop eating, the UCSF researchers said.
A reduction in ultra-processed food consumption can help fight off obesity, which helps avoid osteoarthritis of the knees, Akkaya said.
“Osteoarthritis is an increasingly prevalent and costly global health issue. It is the largest contributor to non-cancer related health care costs in the U.S. and around the world,” she said. “Since this condition is highly linked to obesity and unhealthy lifestyle choices, there are potential avenues for lifestyle modification and disease management.”
Contributing: Katie Camero.
Follow Mike Snider on X and Threads: @mikesnider & mikegsnider.
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