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22 September 2021

Understanding the recent study into Swank and Wahls

"The focus for future research should be the similarities in the diets, not their differences." Read on for our thoughts on this recent study.

Some eagle-eyed OMSers might have noticed recent publicity around the upcoming publication of Impact of the Swank and Wahls elimination dietary interventions on fatigue and quality of life in relapsing-remitting multiple sclerosis: The WAVES randomized parallel-arm clinical trial” in “Multiple Sclerosis Journal – Experimental, Translational and Clinical”. We thought it was important to set the scene and explain the findings of the paper, with some additional context.

Wahls Protocol

As you may be aware, despite the ever-increasing evidence base for the role of diet and lifestyle in the management of MS, and recent findings that higher diet quality is associated with better MS outcomes, no one dietary program is definitively recommended over another, much to the consternation of us OMSers!  One such intervention is the “Wahls Protocol” devised by Dr Terry Wahls, a U.S. physician with MS, who advocates a modified Paleolithic diet that eliminates specific dietary components such as gluten, casein, and lectins. There are similarities with the OMS Program in that both eliminate dairy, processed meats and refined or modified oils. However, whereas OMS advocates a plant-based, wholefood diet plus seafood if so desired, Wahls promotes a diet rich in:

  • Meat and fish
  • Vegetables, especially green, leafy ones
  • Brightly coloured fruit, like berries
  • Fat from animal and plant sources (beef, coconut etc) especially omega-3 fatty acids

And excludes:

  • Dairy products and eggs
  • Grains (including wheat, rice, and oatmeal)
  • Legumes (beans and lentils)
  • Nightshade vegetables, including tomatoes, potatoes, and peppers
  • Sugar

Dr Wahls lives with secondary progressive MS, and has reported that this protocol has allowed her to go from using a wheelchair to walking and being able to cycle for miles. Whilst there have been some small studies of this dietary approach that demonstrate improvements in fatigue levels and quality of life, it should be remembered that the protocol also calls for regular stress reduction techniques and exercise, both of which may be at least partly responsible for its positive effects. It also eliminates many beneficial micronutrients from the diet, and comes at a financial cost to the subscriber.

Indeed, Dr Wahls’ own published research shows that the Wahls’ diet results in several nutritional shortfalls compared to a healthy US eating pattern, that require careful food selection and medical monitoring of nutritional status.

Swank diet

The Swank diet was one of the original building blocks of Professor Jelinek’s research, and ultimately led to the OMS Program as we know it today.  Whilst there are many similarities, the Swank diet has some significant differences to OMS, owing to the level of nutritional research at the time of its inception in the 1950s.  It allowed low-fat dairy, small amounts of red meat and white poultry, with supplementary cod-liver oil and vitamins and less focus on generally high quality diet.

The OMS Program-recommended diet is of considerably higher quality than Swank’s, due to its focus on plant-based eating and wholefoods. Nevertheless, Wahls’ published research on the nutritional adequacy of the Swank diet did not reveal any nutritional shortfalls.

Recent study

In this latest study, 77 patients with relapsing-remitting MS (RRMS) were randomised to either the Wahls or Swank diet and followed-up over a total of 36 weeks. Both groups had similar characteristics (age, sex, BMI, smoking, disability levels etc.) and clinically significant levels of fatigue. All participants had a 12 week introductory period before  randomisation, and were then assessed at baseline, 12 weeks and 24 weeks. 

The main focus of the study (primary endpoint) was any change in perceived fatigue level from baseline to 12 weeks, as assessed by the Fatigue Severity Scale (FSS).  Additional outcomes (secondary endpoints) included perceived fatigue assessed by the Modified Fatigue Impact Scale (MFIS), mental and physical quality of life (QoL) assessed by the Multiple Sclerosis Quality of Life-54 (MSQoL-54), and the 6-minute walk test (6MWT).  There was also an additional 12-week follow-up period to see if the observed results persisted.

Primary outcomes

In terms of the primary outcome, statistically significant reductions were found in fatigue levels (FSS) at both 12 and 24 weeks for both the Swank and Wahls diets.  Both diet groups also showed significant reductions in the secondary endpoint of fatigue measured by MFIS, with the scores at 24 weeks significantly lower in the Wahls group.

In terms of the other secondary endpoint (quality of life), for mental and physical quality of life scores at 24 weeks, both the Swank (47.4% and 50.0% respectively) and Wahls (68.4% and 60.5% respectively) groups demonstrated a clinically significant improvement, with the scores in the Wahls group significantly higher in both areas.  The improvements in walking speed weren’t significant in either group at 24 weeks, but did reach significance in both once those participants who hadn’t adhered to the diets were removed.

Reduction of fatigue

Both diets then were associated with a significant reduction in fatigue levels (59.5% with Swank, 56.8% with Wahls) and improved mental and physical quality of life amongst participants living with RRMS. Between a half and three quarters of people in both groups had a meaningful improvement in fatigue at 12 weeks, and this was sustained by most individuals at 24 weeks. Previous trials of drug treatments for MS-related fatigue have demonstrated similar improvement levels.  

These findings are important, providing further evidence that dietary changes can lead to real improvements in a relatively short space of time, and in one of the most common and often debilitating symptoms for people living with MS.

Offering caution

It is important to offer some caution however, as there were some significant limitations to the study that may have influenced the results.

Firstly, it was a relatively small sample size, and did not include those living with progressive forms of MS, for whom fatigue is also a highly significant factor in their quality of life. Including this group in the research would have made it a more accurate representation of the MS community.

A study period of 24 weeks is also likely to be too short to demonstrate the “real-world” benefits of each diet, as we know from our own experience that it often takes 3-5 years to see the full benefits of the OMS Program. There is also an important distinction to be made between the Swank and OMS diets, and it perhaps would be more useful to compare these groups directly, as OMS is rapidly growing in popularity within the MS community.

Interpreting results

Unfortunately, the way the trial was designed and conducted made the results very difficult to interpret.  In terms of methodology, the researchers were based at the University of Iowa, including Dr Wahls, who is a clinical professor of internal medicine there. It was perhaps a missed opportunity for the study to be centred elsewhere. We understand lifestyle-intervention studies are complex to evidence and it is a shame that these interesting results could be diluted by criticisms of possible unconscious bias.

The diet groups were not blinded, so participants knew which diet they were being given, and would have likely known which diet the investigators were promoting. This, in combination with the fact that there was no control group eating a standard diet, means that the results are potentially muddied by placebo response, in particular with the apparently slightly improved outcomes in the Wahls group. 

When it was announced in August 2016 that the national MS Society in the US had granted $1m to Dr Wahls’ team to conduct this study, there was some discussion amongst the international MS research community, noting that the trial could be more robustly designed. For example, the lack of a control group eating a standard diet, against which to compare any change in outcome for those eating the two diets. The short duration was also an issue and meant that important outcomes such as relapses and disability could not be measured, given that they would not be likely to change in this timeframe.

The study was also too small to detect any difference in these outcomes.  In the intervening five years, multiple studies have now been published showing the strong associations of better diet quality with better health outcomes, not only in terms of fatigue and quality of life, but in the key outcome of disability, including work from North American Research Committee on Multiple Sclerosis (NARCOMS) Study, and recent work from the HOLISM study at the Neuroepidemiology Unit at the University of Melbourne.  Importantly, Dutch researchers have recently shown that in their large sample of people with MS, those following the OMS Program had the highest diet quality.

Living up to expectations

Sadly, this new research has not then lived up to expectations. Because of its methodological problems, the findings have probably only served to confuse the issue of diet in health outcomes for people with MS.  

As we always point out, the OMS program is much more than just a diet, as in fact is the Wahls protocol, so the real-world benefits of both are not easily transferable from this study. But as the authors quite rightly point out, the focus for future research should be the similarities in the diets, not their differences. It is likely that any benefits come from their common underlying mechanisms, such as effects on the gut microbiota, levels of inflammation and oxidative stress, rather than a unique characteristic of one diet over another. 

It is here that we must look further to unlock those factors that can affect the course of the condition, and allow us to live long and healthy lives with MS. While the debate about diet and MS will undoubtedly continue, those currently following the OMS Program-recommended diet can be confident that by sticking with it, they are eating a very high quality diet that has been associated with better long-term health in several major studies.