There is little direct evidence to suggest that MS makes a significant difference to life expectancy. Older studies have shown a difference of around six to ten years between people who do not have MS and people who do, but there are a great many factors impacting this figure such as other health conditions and lifestyle.
To put this number into context, a diagnosis of diabetes is thought to reduce life expectancy by around 10 years. Death from infection, suicide and heart disease are higher for people with MS than for the general population. People included in older studies like the ones which came up with these numbers didn’t have access to DMDs for much or sometimes any of their disease course and MS diagnosis occurred later. Life expectancy for people with MS has risen in the last 25 years and no doubt will keep rising as new research leads to new treatments.
Canadian studies indicate that improving lifestyle factors in MS is very likely to be protective in terms of life expectancy, and while the study on OMS and life expectancy hasn’t been done yet, there is every reason to think that it would be protective. After all, the 'side-effect' of OMS is to protect you from co-morbidities that both make MS itself worse (heart attack, stroke, diabetes) and also negatively impact your life expectancy. In reality, there is every reason to think that someone following the OMS Program long-term would have at least the same life expectancy of any other healthy adult.