Ultra-processed foods linked to worse muscle health in new study

As noted in this research, ultra-processed foods contain additives as well as high levels of sugar and salt. How ultra-processed foods relate to muscle quality hasn’t been a major focus of research.

This analysis was a cross-sectional secondary analysis that used baseline information from a long-term study called the Osteoarthritis Initiative.

For the current analysis, participants were at risk for knee osteoarthritis, a condition where there can also be muscle problems.

Participants did not have hip or knee osteoarthritis, or other conditions like rheumatoid arthritis or diabetes. However, some participants had radiographic data that could indicate early osteoarthritis.

The average age of participants was just under 60, and researchers included 615 participants. Almost two-thirds of participants had overweight, and just under one-fourth had obesity, based on body mass index (BMI) data.

Researchers looked at participants’ reports about their diets and evaluated the consumption of ultra-processed foods. They looked at thigh MRIs to assess fat infiltration into the muscle, focusing on 10 different muscles in the thigh.

Researchers found that overall, higher intake of ultra-processed food was associated with higher levels of fat infiltration in the thigh muscles.

Speaking to Medical News Today, study author Zehra Akkaya, MD, associate professor of radiology at Ankara University Faculty of Medicine, in Turkey, and researcher, consultant, and former Fulbright Scholar at the UCSF Department of Radiology and Biomedical Imaging, Clinical & Translational Musculoskeletal Imaging Research Group, summarized the main findings this way:

“In a study of over 600 adults at risk of developing knee osteoarthritis, we found that diet quality plays an important role in muscle health. Specifically, independent of total calorie intake or overall fat consumption, a higher intake of ultra-processed foods was associated with greater fat accumulation within the thigh muscles, as seen on MRI scans.”

When looking at individual muscle groups, those with the strongest relationship to ultra-processed food consumption were the adductor muscles in the model that adjusted for abdominal circumference.

Overall, women had greater levels of fat infiltration into the thigh muscles than men. However, the relationship between ultra-processed foods and fat infiltration into the thigh muscles did not appear to be affected by sex.

Sensitivity analyses adjusting for dietary fat intake still found a significant relationship between ultra-processed food consumption and fat infiltration for all thigh muscles as well as the adductor and flexor muscle groups.

The findings for the extensor muscles remained significant in the model that adjusted for abdominal circumference.

Additionally, the relationship between eating ultra-processed foods and fat infiltration into muscle was stronger for participants who had worse damage on knee images.

This research specifically focused on an older population already at risk for knee osteoarthritis, which limits generalizability to other groups.

Researchers also note that people in this group may have a greater risk for frailty and disability. In their paper, they conclude that “the findings may not be fully generalizable to populations outside the age range and characteristics of the OAI [Osteoarthritis Initiative] participants.”

They also acknowledge that there could be confounders that they missed.

Additionally, most participants were non-Hispanic and white. The research also focused on fat infiltration in thigh muscles, so it is unclear if the results would be the same in other muscle groups.

Furthermore, some of the data — for instance, regarding diet — was self-reported, which can lead to errors.

The study authors also emphasized that the percentage of the annual diet made up of ultra-processed foods is increasing and is even higher in the modern American diet than it was in their research.

Finally, this research did not evaluate long-term data. Akkaya told MNT:

“We would also like to note that this study was cross-sectional in design, which means we cannot draw conclusions about cause and effect. Future research should therefore use longitudinal approaches to better understand potential causal relationships, particularly across different age groups and diverse populations, given how widespread ultra-processed foods have become.”

Future research could further explore how diet affects individuals who already have osteoarthritis, based on the differences observed here between participants who had worse radiographic images and those who had normal ones.

It could also look at how the use of glucagon peptide-1 receptor agonists (GLP-1s), such as semaglutide medication, may affect outcomes in this area of research.

Though this is only the beginning of research in this area, these findings indicate another component to possibly target when it comes to muscle health.

Patrick Kee, MD, PhD, a cardiologist at Vital Heart & Vein, who was not involved in this research, commented on the finidngs for MNT.

“Since muscle quality is essential for joint stability, the UPF [ultra-processed food]-induced fatty degeneration in thigh muscles may accelerate the onset and progression of knee osteoarthritis, a leading cause of global disability,“ Kee told us.

According to him, “these findings suggest that clinical management of musculoskeletal and metabolic health must go beyond simple caloric restriction and weight loss.“

“Instead,“ he emphasized, “it requires targeted public health and clinical interventions that emphasize dietary quality, specifically reducing the consumption of ultra-processed foods and favoring minimally processed options. This approach aims to preserve skeletal muscle integrity and mitigate ectopic visceral adiposity.”

The study results also more broadly point to another possible reason to limit consumption of ultra-processed foods. Ultra-processed foods are also linked to other health concerns, such as a higher risk of death related to cardiovascular disease and all-cause mortality.

Mir Ali, MD, a bariatric surgeon and medical director of MemorialCare Surgical Weight Loss Center at Orange Coast Medical Center in Fountain Valley, CA, likewise not involved in the recent study, told MNT that “these findings provide further evidence to advise patients to reduce their intake of ultra-processed foods.“

“While it is not yet clear from this specific study if increased thigh muscle fat accelerates joint damage, numerous studies have established that ultra-processed foods increase the risk of diabetes, heart disease, and cancer. Limiting these foods is essential for improving overall health,” Ali concluded.