Our microbiomes are clearly very important, but they don’t come close to explaining why you get MS and whether or not one of our microbiomes is causal in MS. Yes, there are multiple microbiomes in and on our bodies. At the moment the attention is all focused on the gut microbiome, in particular, the distal colon. Why? Because it is easy to collect poo samples. But why the colonic microbiome in MS and not another site?
If I had the time and interest I would focus on other sites, in particular, the paranasal sinuses and lungs. There is a hypothesis that infections in the paranasal sinuses are more common in MSers and can trigger MS. There is some evidence, albeit weak, that MSers are more likely to have had sinusitis than control subjects. What organisms are causing these episodes of sinusitis?
The other site is the lungs. Smoking and solvent exposure increases your risk of getting MS. It does not appear to be tobacco itself which is the risk factor because the oral use of tobacco is not associated with an increased risk of getting MS. In fact, oral tobacco use appears to lower the risk of getting MS. The overlap between smoking and solvents could be via the microbiome in the lung and/or lower respiratory tract.
For me, the most exciting data points to our internal or systemic microbiome, i.e. the viruses and bacteria that live within our bodies. EBV is an exogenous virus that lives with our bodies; in fact inside memory B-cells the major therapeutic target of our treatments. The evidence for EBV being the cause of MS is so overwhelming that we are planning an anti-EBV vaccine prevention trial and we are also exploring anti-viral strategies against EBV.
How EBV causes MS is unknown, but one hypothesis is via its induction of HERVs (human endogenous retroviruses). EBV simply wakes-up, or resurrects, these dormant viruses which then activate the immune system and trigger autoimmunity. This is why we are so keen to target HERVs with antivirals as a treatment strategy for MS.
But getting back to the gut microbiome. In my opinion, it is simply the latest research bandwagon with everyone making premature claims that by manipulating it we may be able to prevent people from getting MS in the first place. Or alternatively, once you have MS we may be able to treat your disease by manipulating the microbiome with diet or by providing you with ‘good’ bugs. This has resulted in a new generation of quacks offering vulnerable MSers faecal transplants to ‘treat’ and ‘cure’ them of having MS. There is simply zero evidence to support these claims so please avoid being hoodwinked into having a faecal transplant, which may be dangerous.
The following microbiome paper is interesting and shows that (1) daily microbiome variation is related to your food choices, but not to conventional nutrients, (2) daily microbiome variation depends on at least two days of dietary history and most importantly (3) similar foods have different effects on different people’s microbiomes. Therefore, there will be no magic bullet bacterial pill, super-poo transplant or some superfood diet that will necessarily alter your microbiome.
My advice is to eat well and eat sensibly, real-food rather than processed food, and get off the microbiome bandwagon until some class 1 evidence emerges to contrary.
Johnson et al. Daily Sampling Reveals Personalized Diet-Microbiome Associations in Humans. Cell Host Microbe. 2019 Jun 12;25(6):789-802.e5.
Diet is a key determinant of human gut microbiome variation. However, the fine-scale relationships between daily food choices and human gut microbiome composition remain unexplored. Here, we used multivariate methods to integrate 24-h food records and fecal shotgun metagenomes from 34 healthy human subjects collected daily over 17 days. Microbiome composition depended on multiple days of dietary history and was more strongly associated with food choices than with conventional nutrient profiles, and daily microbial responses to diet were highly personalized. Data from two subjects consuming only meal replacement beverages suggest that a monotonous diet does not induce microbiome stability in humans, and instead, overall dietary diversity associates with microbiome stability. Our work provides key methodological insights for future diet-microbiome studies and suggests that food-based interventions seeking to modulate the gut microbiota may need to be tailored to the individual microbiome. Trial Registration: ClinicalTrials.gov: NCT03610477.