Could Ultra-Processed Foods Make Your MS Worse?

A new study found that, for people with early MS, a diet high in ultra-processed foods appeared to worsen disease activity.

By Becky Upham — Published on October 1, 2025

Key Takeaways

• People with early multiple sclerosis who ate more ultra-processed foods had more relapses and brain lesions than people who ate very little of these foods.
• These foods did not increase participants’ risk of developing advanced MS, but it did worsen disease activity once symptoms began.
• Ultra-processed foods may fuel inflammation in the brain by disrupting the gut, altering nerve cell membranes, and putting stress on brain cells.

Higher consumption of ultra-processed foods appeared to accelerate the onset of multiple sclerosis symptoms among adults who were being monitored for potential diagnosis, a new study has found.

[1]

Before some people are diagnosed with multiple sclerosis (MS), they experience what experts call clinically isolated syndrome (CIS): a single episode of symptoms — including vision problems, numbness, or weakness, that lasts at least a day — caused by inflammation in the nervous system. Some people with CIS will go on to develop multiple sclerosis, while others may never have another episode.

[2]

The new study has found that among people monitored after a CIS episode, those who ate more ultra-processed foods had more relapses and increases in brain lesions over time than those who ate less of these unhealthy foods. 

The study results were presented at the 2025 Congress of the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS) and have not yet been peer reviewed.

Researchers found that although a diet with more ultra-processed food didn’t ultimately affect whether someone with CIS went on to develop MS, it did appear to worsen disease activity among those who were already showing other early signs of the disease.

What this suggests is that ultra-processed foods seem to act as a chronic inflammatory accelerant, rather than a disease trigger, says the lead author, Gloria Dalla Costa, PhD, a research scientist in nutrition at the Harvard T.H. Chan School of Public Health in Boston.

“Eating more of these types of foods clearly exacerbated disease activity in people with clinically isolated syndrome,” says Dr. Dalla Costa.

Ultra-processed foods are products that go through multiple steps of industrial processing and often include additives such as preservatives, emulsifiers, and flavor enhancers.

Examples include packaged snacks, soft drinks, instant noodles, frozen meals, and processed meats like hot dogs.

[3]

Biomarkers in the Blood Can Say a Lot About Diet

The research team analyzed data from 451 people enrolled in the BENEFIT trial, which began in 2002 and followed individuals with clinical isolated syndrome for five years. Instead of relying on food diaries, the researchers used a validated “metabolomic signature” — a panel of 39 blood markers from participant samples — to estimate how much ultra-processed food each person ate.

This study is one of the first to use a blood analysis for this assessment rather than relying on self-reported food questionnaires.

“This methodology is important because diet questionnaires can be inaccurate,” says Rob Bermel, MD, the director of the Mellen Center for MS Treatment and Research at Cleveland Clinic.

Ultra-processed Foods Increase Risk of MS Relapses

Over the five-year study period, 208 participants were diagnosed with clinically definite multiple sclerosis. 

By combining blood data with magnetic resonance imaging (MRI) scans and participant health outcomes, the researchers could see how dietary exposure was linked to the progression of early MS over time.

Participants who consumed the most ultra-processed foods had about 30 percent more relapses over five years than those who ate the least.

Participants in the high-consumption group also had:

• More active inflammatory lesions on MRI by year two
• Greater lesion volumes over the five-year follow-up
• Lower neurological function scores

“These findings were independent of other factors such as age, sex, body weight, vitamin D, smoking, or treatment assignment,” says Dalla Costa.

“By using blood-based metabolic markers, the study provides stronger evidence that ultra-processed foods are linked to increased inflammation in early multiple sclerosis,” says Dr. Bermel, who was not involved in the research.

Unhealthier Diets Didn’t Increase the Risk of Developing MS

A diet full of highly processed foods did not increase a participant’s risk of going from CIS to clinically definite multiple sclerosis. Instead, diet appeared to influence the severity and frequency of disease activity once symptoms had already begun.

READ MORE