Probiotics and MS: What a New Trial Says About Fatigue (and What It Can’t)

On this page

1. 01Key Takeaways
2. 02What Did the New Trial on Probiotics and MS Actually Find?
3. 03Why Can’t This Trial Prove Probiotics Help MS?
4. 04What Does the Wider Evidence on Probiotics and MS Show?
5. 05Why Might Fatigue Be the Symptom That Responds?
6. 06Should You Try Probiotics or Change Your MS Diet?
7. 07What About Omega-3s for MS?
8. 08Where Does a Naturopath Fit Alongside Your Neurologist?
9. 09Frequently Asked Questions
10. 10References

By Adrian Stone, BHSc (Nutritional Medicine), BHSc (Naturopathy), Living Holistic Health. Probiotics and MS are back in the news: here’s what a new trial actually found, and what it can’t tell you yet.

If you’ve seen this month’s headlines saying probiotics “reduce fatigue and disability” in MS, this post is for you. In fact, the study behind them is more interesting than that. It’s also more limited, and both halves of that matter if you’re living with MS.

It follows on from Part 1 of my gut series, where I made the case that your gut is not like Las Vegas: what happens there doesn’t stay there. If you missed it, start with what the gut microbiome says about multiple sclerosis.

Key Takeaways

How I weigh the evidence here. Fermented foods have a long traditional history, so where they come up, I set the traditional layer beside the trial layer and label each one. Probiotic capsules and omega-3 supplements are modern products with no traditional-use history, so for those it’s trial evidence only.

What Did the New Trial on Probiotics and MS Actually Find?

Researchers in Cairo randomly split 60 adults with relapsing-remitting MS into two groups. Importantly, everyone stayed on their usual MS medication. Half also had two cups of probiotic yoghurt and a probiotic yeast tablet every day for three months. That group reported less fatigue, lower depression scores and better quality of life, and their disability scores fell.

Meanwhile, on blood tests, IL-6, an inflammatory signal, fell in the yoghurt group, while IL-10, the body’s “stand down” signal, rose. The trial was published in September 2026 in The Egyptian Journal of Neurology, Psychiatry and Neurosurgery.

A few details are worth knowing:

• Who took part. Adults aged 20 to 60 with relapsing-remitting MS, the form with flare-ups followed by recovery, and mild disability, clinically stable for the year before they joined. About four in five were women.
• Fatigue was the main measure. All three parts of the fatigue scale improved: physical, cognitive and psychosocial.
• A neurologist who didn’t know the groups scored disability. That’s the strongest part of the design, because expectation can’t easily move a blinded score.
• IL-6 explained about 15% of the differences in fatigue between people at three months.
• Nobody dropped out, and the authors reported no adverse effects.

Why Can’t This Trial Prove Probiotics Help MS?

There was no placebo, and everyone knew who was eating the yoghurt (an “open-label” design). Only that group got reminder calls and extra attention. Fatigue, mood and quality of life are self-reported, so expectation alone can move them. Moreover, the yoghurt and yeast came together, and nobody measured gut bacteria, so the trial can’t show the microbiome changed.

The authors say much of this themselves, too. In fact, they describe their findings as preliminary associations, not proof that probiotics themselves made the difference. That’s the honest reading, and it’s to their credit.

Two more things temper the result. First, the trial was registered after it was finished. Registering first locks in what you’ll measure, so a late registration makes it harder to rule out a shift in focus. Second, the team tested many outcomes without adjusting for multiple comparisons, which raises the odds that a chance result looks real.

That’s not me being dismissive, but disability scores moving within three months, in a group stable for a year, would be a surprising result. So treat it as a signal worth testing in a blinded trial, not a finding to act on.

What Does the Wider Evidence on Probiotics and MS Show?

In contrast, a 2026 meta-analysis pooled six placebo-controlled trials with 282 people. Probiotics improved fatigue and pain, and lowered inflammatory markers, mainly C-reactive protein. However, they didn’t change disability scores, and they had no significant effect on depression. On mood, that’s the opposite of the new Cairo trial, which is exactly why placebos matter.

I covered the retraction story in Part 1, so briefly: a 2017 Iranian trial was cited for years as proof that a probiotic capsule improved disability and mood in MS. However, it was retracted in 2025. An older pooled analysis from 2021 reported mood and disability benefits, rated “very low certainty”, and it was written before that retraction.

A separate 2026 update re-examined the inflammatory-marker evidence with the retracted trials in view. I haven’t been able to read its full results, so I’m noting it here rather than summarising it.

The pattern on probiotics and MS is fairly clear so far. Fatigue has the most consistent signal across trials, while disability and mood don’t, at least not yet.

Why Might Fatigue Be the Symptom That Responds?

The trial’s own clue is IL-6, an inflammatory signal that tracked with fatigue. Gut bacteria and the compounds they make help set the body’s inflammatory tone. Researchers have long linked inflammatory signalling to MS fatigue. Similarly, inflammation and fatigue improved together in the pooled trials. Even so, it’s a plausible link, not a proven one.

Two of the four root drivers I see in almost every case in clinic matter here: chronic inflammation and a stress-dominant nervous system. A body stuck in stress mode struggles to rest properly, and fatigue is often where that shows.

Of course, fatigue in MS rarely has one cause. Sleep, pain, mood, heat and how much you’re moving all feed into it. That’s why a single probiotic was never going to be the whole answer. Fatigue also fluctuates from week to week. As I often tell my patients, the path to progress is never linear.

Should You Try Probiotics or Change Your MS Diet?

Food first. Notably, the trial’s main vehicle was a fermented food, yoghurt, not a capsule. In a Stanford randomised study, a diet high in fermented foods raised gut diversity and lowered inflammatory markers in healthy adults. Similarly, in MS, higher diet quality is linked with less disability and depression. Any supplement is a conversation with your neurologist first.

Here are both layers of evidence for fermented foods.

Traditional usePeople have made and eaten fermented foods for thousands of years. In Ayurveda, the classical texts list buttermilk (takra) among the pathya, or wholesome, foods, and describe it as light and easy to digest. That’s a statement about digestion within the tradition, though, not about MS.

What the trials showIn the Stanford study, 18 healthy adults ate more yoghurt, kefir, kimchi and other fermented vegetables. Over the study, their gut diversity rose and 19 inflammatory proteins fell, IL-6 among them. Unlike the fermented-food group, a comparison group on a high-fibre diet didn’t show the same drop. Admittedly, nobody in it had MS.

SafetyFermented foods are generally well tolerated, though dairy doesn’t suit everyone. However, live microbes are a different matter if your immune system is suppressed, which some MS medicines do. Rare bloodstream infections from probiotic organisms, yeasts included, have been reported in very unwell or immunocompromised people. So before adding a probiotic supplement, ask your neurologist whether your medication is one of them.

As for an MS diet, no single eating pattern has earned the title. Still, the pattern with the most support is familiar: plenty of vegetables, legumes and wholegrains, less added sugar and less processed meat. I covered that evidence in Part 1, and you’ll also find more on diets for autoimmune conditions here.

What About Omega-3s for MS?

The evidence is weaker than its reputation. A meta-analysis of four placebo-controlled trials found omega-3 supplements didn’t change disability scores in MS, although one inflammatory marker, TNF-α, fell. Furthermore, a 2024 review with genetic analysis found no consistent causal link between omega-3s and MS. Even so, oily fish as part of a good diet is reasonable.

The authors concluded omega-3s may not make a clinically meaningful difference to disability or inflammation in MS, and called for more trials.

The 2024 review is especially interesting because it went beyond trials. It also used genetic data to test whether higher omega-3 levels could cause a change in disease risk. For rheumatoid arthritis and lupus, the answer leaned yes. For MS, however, it didn’t hold up consistently.

Where Does a Naturopath Fit Alongside Your Neurologist?

Beside them, not instead of them. Your neurologist leads your MS care. Our part is the nutritional and lifestyle work that sits alongside it: diet quality, digestive symptoms, fatigue, sleep and stress. That’s the everyday ground a specialist appointment isn’t designed to cover.

In practice, that starts with a long first appointment. We build a timeline of when things started and what changes them, take a system-by-system history, and go through your diet and stress load. I also read every report you bring. Importantly, anything new you’re considering, a probiotic included, gets raised with your MS team before it starts.

Nothing here is a reason to change a medication. So if this post raises a question, take it to your neurologist.

We want the body to do most of the work. We just want to create the right conditions for it.

Frequently Asked Questions

Do probiotics help MS fatigue?

Possibly, modestly. A 2026 meta-analysis of six placebo-controlled trials found probiotics improved fatigue in MS. The new Cairo trial also linked probiotic yoghurt with less fatigue, but without a placebo. Still, the effect isn’t certain yet, so discuss it with your neurologist before trying a supplement.

Can probiotics reduce MS disability?

Not on current evidence. When six placebo-controlled trials were pooled in 2026, probiotics made no difference to disability scores. The new Cairo trial reported lower scores after three months, but it had no placebo and needs repeating in a blinded trial.

Do probiotics help depression in MS?

The evidence conflicts. The new Cairo trial, which had no placebo, reported lower depression scores, but pooled placebo-controlled trials found no significant effect on depression. If mood is a concern, raise it with your GP or neurologist, because depression in MS deserves proper care of its own.

Are fermented foods or probiotics better for MS?

So far, nobody has compared them head to head in MS. The new trial used a fermented food, yoghurt, together with a yeast tablet. Fermented foods are the lower-risk starting point and fit within a good diet. Supplements, though, are a conversation with your neurologist.

Can I take probiotics with my MS medication?

Ask your neurologist or pharmacist first. The trials reported no serious problems, but some MS medicines suppress the immune system. In immunocompromised people, however, live microbes have rarely caused bloodstream infections. Your MS team knows your treatment and can advise you.

What is the best diet for MS?

No single MS diet has the evidence to be called the best. In a large survey of people with MS, higher-quality diets with more vegetables, legumes and wholegrains and less added sugar and processed meat were linked with less disability and depression. It was observational, so it can’t prove cause.

References

General information only, not individual medical advice. Always discuss supplements and herbal medicines with your treating practitioner.