The role of environmental factors in the development and progression of multiple sclerosis is always of particular interest to patients. The scientific findings on this complex of topics are often the starting point for alternative therapy concepts, which are offered and discussed on the World Wide Web. The discussion about vitamin D can serve as a current example – and accordingly, what was reported at the ECTRIMS specifically on the subject of environmental factors should be of interest.
The importance of environmental factors is based, among other things, on the observation that identical twins – despite identical genetic makeup – only both develop MS in about 30% of cases. This finding proves that MS cannot be solely based on a congenital predisposition. Moreover, the regionally different prevalence of MS points to the importance of environmental factors. Thus, the higher prevalence of the disease in countries with less sunlight justifies the scientific interest in vitamin D.
In short, in recent years smoking, seropositivity for EBV (Epstein-Barr Virus), low vitamin D levels/low sun exposure, shift work, and obesity in adolescence have been proven to be environmental factors associated with MS. In addition, there are many attractive hypotheses about other environmental factors that could play a role in the development of MS.
The ultimate goal is to scientifically prove whether and how the course of the disease can be influenced by modulating such environmental factors, but this is anything but trivial. Unfortunately, it is often the case that an attractive hypothesis is considered sufficient to promote the modulation of environmental factors, whether through a special diet, intake of dietary supplements, or behavior changes, as scientifically justified.
However, Prof. Dr. Ralf Linker from the University of Regensburg made it clear how difficult it is to scientifically investigate an attractive hypothesis and demonstrate its significance for MS patients. He investigated a salt-rich diet as a risk factor for MS. This hypothesis is attractive because MS has a particularly high prevalence in countries with a high prevalence of the salt-rich “Western diet” and the pro-inflammatory effect of salt could be demonstrated in animal models. Professor Linker and his working group were able to show that a high salt intake influences the microbiome and that the resulting pro-inflammatory effects could be reversed by supplementing with probiotics. Thus, it was very elegantly shown experimentally that diet and microbiome interact “immunologically”. Prof. Linker emphasized, however, that he would not yet base therapeutic recommendations on his results. It will be interesting to see how strategies for influencing the microbiome will develop.
In the further course of the scientific session on the importance of environmental factors, several working groups unanimously emphasized the importance of obesity as a risk factor in MS. The working group of Ellen Mowry from Johns Hopkins University in Baltimore showed that an increased BMI (Body Mass Index) is much more strongly associated with atrophy of the gray matter than, for example, low vitamin D levels.
Prof. Mar Tintore, Barcelona, reported on the studies on the prognosis of patients with a first clinical relapse (the so-called Barcelona cohort with more than 1000 patients) considering the modifiable risk factors smoking and vitamin D. Especially for smoking, there was a dramatic influence on the risk of progression in patients who already had a high risk of rapid disease progression due to other parameters.
These results clearly prove that it makes sense to primarily modulate risk factors such as smoking and obesity, which are easy to address and whose modulation also has a generally positive health effect.
