Living Well with Multiple Sclerosis

Webinar Highlights – Diet in MS: What the Evidence Tells Us | S7E24

Date: November 19, 2025
Host: Overcoming MS (Geoff Allix)
Guests: Dr. Jonny White (OMS Medical Advisor), Dr. Steve Simpson-Yap (Senior Research Fellow, Neuroepidemiology Unit, Univ. of Melbourne)

Episode Overview

This special episode shares highlights from the Overcoming MS (OMS) 10th Anniversary webinar series, focusing on the critical question: What does the evidence tell us about diet in MS? Dr. Jonny White interviews Dr. Steve Simpson-Yap, an epidemiologist specializing in lifestyle and diet factors in autoimmune diseases, particularly MS. The discussion explores the complexity of studying diet in MS, the different diets people try, research methodologies, and the current state of evidence on whether dietary choices can influence the course of MS.

Key Discussion Points & Insights

1. Why Study Diet in MS?

• Biological plausibility:

  • Diet impacts factors linked to MS (body mass, fat/vitamin levels, gut microbes).
  • Healthy diets often correlate with other positive lifestyle habits (exercise, not smoking, supplementation).
  • Quote (A) [00:00]:

    “People that have a good diet are potentially more likely to have better physical activity, to take more supplements, to not smoke... All of these things could comprise a healthy lifestyle set of behaviors which can positively affect their disease...there's strong potential for diet-based intervention to improve MS risk and modulate disease.”

• Motivation within the MS community:

  • Nearly half of people with MS report following a specific diet to improve their MS.
  • Quote (A) [06:00]:

    “…People with MS are motivated, they want to take charge, they want to take action that's going to help their disease and not just wait on, you know, taking the drug, whatever the neurologist tells them.”

2. Complexity of Diet Research in MS

• Different Diets Recommended:

  • OMS diet (plant-based + seafood; no meat/dairy)
  • McDougall diet (plant-based, no seafood)
  • Wahls Elimination diet (hunter-gatherer/paleolithic)
  • Other popular diets: Mediterranean, low-carb, ketogenic, vegetarian, vegan, intermittent fasting
  • These diets often conflict; they cannot “all be right.”
  • Quote (A) [04:00]:

    "...these programs are idiosyncratic and varied. And importantly, they're not complementary per se. Some of them actually are quite distinct....so those can't both be right..."

• Challenges in Conducting Studies:

  • Randomized controlled trials (RCTs) are far more complex for diet than for drugs.
  • Issues include adherence, recall bias, accurately measuring intake, and the lengthy timescales needed to assess progression.
  • Objective dietary measurement (e.g., food diaries, detailed questionnaires) is burdensome for participants.
  • Quote (A) [13:52]:

    “I wish there was a way I could just give everybody in a clinical trial a pill. And I say, this has all the food and nutrition you need on it… Unfortunately, our diet is not like that.”

3. Research Methodology: Observational vs Clinical Trials

• Observational studies are the foundation:

  • Cross-sectional: Measure exposure and outcome at a single point in time.
  • Longitudinal/prospective: Track people’s exposures (diet) and outcomes over time (5–10 years ideal for disability progression).
  • Quote (A) [16:30]:

    “A cross-sectional study just measures your exposure and your outcome at one point in time... you don't know... is it because the better exposure causes them to have a better outcome, or is it...the outcome causing the exposure? ...The way you can better assess this is doing a longitudinal study..."

• Measurement approaches:

  • Short questionnaires vs detailed food frequency surveys vs food diaries vs (impractical) lab measurement.
  • Trade-off between accuracy/detail and participant burden.

4. What Does the Current Evidence Show?

• Disability Progression:

  • Higher overall diet quality is associated with less disability progression and reduced risk of accumulating disability (Holosom study: 7.5-year data).
    • Example finding: Top diet quality: 0.3 points less disability accrual, ~40% less risk of increasing disability.
  • Quote (A) [23:13]:

    “We found that those in the top two levels of diet quality had 0.3 points less disability accrual and those same people also had 41, 36% less risk of increasing their disability over time...”

• Quality of Life:

  • Better diet quality tracks with higher QoL (physical and mental), ~0.5 points better in those at highest diet quality.

• Fatigue and Depression:

  • No strong association demonstrated prospectively between diet and fatigue (i.e., clinical trials focusing on fatigue may not be worthwhile based on current evidence).
  • Some evidence for links with improved depression and QoL.

• Limitations of Evidence:

  • Most studies are small, cross-sectional, or with short follow-up.
  • Diverse populations and heterogeneous methods make comparison and conclusions tricky.
  • No single “diet” emerges with robust, indisputable evidence—most findings point to overall healthy diet quality as beneficial.

5. The UK MS Register Study: Looking Ahead

• UKMS Register:
  • National, longitudinal survey (England, Wales, Scotland; >10,000 people since 2011).
  • Repeat comprehensive diet questionnaires (2015–16, again recently with additional 3,000 participants).
  • Statistical approach: Index analysis (aligns reported diet to OMS, Mediterranean, Wahls, etc.).
  • Goals: Determine which diet indices predict MS progression, relapse, fatigue, mood, and correlate with MRI data over a 10-year span.
  • Internal and external validation (cross-checking UK results using Australian Longitudinal Study for replication).
  • Quote (A) [26:10]:

    “…my hope that the studies that we do will give guidance to people living with Ms. Whether and how diet can really predict their Ms. Progression and how they can improve their diet to improve their life.”

6. Translating Epidemiology to Clinical Practice

• Doctors hesitant to recommend diet due to higher standard of proof expected (ideally RCTs, lacking in diet research).

• Caution needed not to overpromise on diet’s effects in absence of definitive causal trials.

• Encouragement: Evidence is mounting, but until it’s rock-solid, focus should be on overall diet quality and core healthy behaviors (e.g., quitting smoking, staying active).

  • Quote (A) [28:15]:

    “...in terms of why a neurologist...doesn't recommend diet for ms, is they really, they have a level of evidence...they don't believe... the evidence is not there for them to make that same claim to their patient.”

• Quote (A) [41:01]:

  “The evidence is there definitely that if you follow a good diet it will improve your heart health and your...longevity. But the thing we just want to make sure is that the evidence is also there for their MS...if we can show that diet is something that you can modify to improve your disease, then that is a very powerful thing...”

• Recent Neurology editorial: “There is sufficient evidence now to recommend diet quality for people with MS.” (C [41:43])

7. Outlook: The Next 5–10 Years

• Large, prospective, collaborative studies are underway and will increase the robustness and detail of evidence.
• Stopping smoking remains the most proven modifiable lifestyle factor for MS risk/progression.
• Hope for stronger, specific evidence on the roles of diet and physical activity.
• Quote (A) [39:35]:

  “...I hope in five or 10 years...people have a much greater idea of whether and how diet can potentially modify their disease.”

Notable Quotes & Memorable Moments (with Timestamps)

• On the value—but limitations—of current diet evidence:

  "There’s increasing evidence to suggest that a healthy diet may have some beneficial health effects, but unfortunately, they don't necessarily know if that translates to MS, whether it will reduce your disability progression or your relapse risk."
  — Dr. Steve Simpson-Yap (A) [30:43]

• On why “diet trials” are uniquely difficult:

  "I wish there was a way I could just give everybody in a clinical trial a pill...you just take this every morning. Unfortunately, our diet is not like that. This isn’t the Jetsons yet."
  — Dr. Steve Simpson-Yap (A) [13:52]

• On the hope for personalizing feedback from big studies:

  "...if someone was accidentally closely following the Overcoming MS Program, but they'd never actually heard of the organization, we were able to say, actually, do you realize what you're doing is pretty much overcoming ms?"
  — Dr. Jonny White (C) [36:03]

• On taking charge in MS:

  “...people with MS are savvy and active...the first thing they do is go on Google and say, what can I do to improve my...What lifestyle can I follow? ...What we want to do with our data is just to make sure that what they follow is best for them and...the outcomes they want to realize.”
  — Dr. Steve Simpson-Yap (A) [36:27]

• On clinical measurement of quality of life:

  "Quality of life is inherently subjective...there is no objective measure...it's scored as per an algorithm to give the scores that we then use for analyses."
  — Dr. Steve Simpson-Yap (A) [37:41]

Highlighted Timestamps for Key Segments

• 00:00–04:00 — Introduction: Biological plausibility, healthy lifestyle behaviors, why study diet in MS.
• 06:00–07:50 — Motivation in the MS community; overview of popular MS diets and potential pitfalls.
• 13:50–17:00 — Why clinical “diet trials” are challenging; importance of observational studies.
• 23:13–26:00 — Holosom and other evidence: Diet quality linked to reduced disability progression and improved QoL.
• 26:00–29:00 — UK MS Register and planned analysis approaches.
• 31:50–33:23 — Importance of study duration; minimum years of follow-up for robust results.
• 39:35–41:43 — Hopes for future research; advice on current best practice while evidence matures.

Takeaway Messages

• There is growing, but not yet definitive evidence that a healthy diet is beneficial for MS—particularly for long-term disability and quality of life.
• No single “MS diet” is proven above all others; however, general diet quality seems to matter most.
• Ongoing (and future) long-term, large-scale studies (like the UK MS Register) are vital and will shape future guidance on diet for people with MS.
• Doctors require high standards of evidence before making recommendations but may soon have enough data to confidently recommend dietary changes for MS based on robust, replicated findings.
• For now: Focus on a generally healthy diet, physical activity, and not smoking—these are beneficial for overall health, and evidence is mounting for specific benefits in MS.