Multiple sclerosis and a New Year’s Resolution
Perhaps the most common New Year’s resolution is losing a bit of weight – a good intention that is especially important to people with MS.
In recent years, obesity has emerged as an important factor influencing whether a person will develop MS, and how well they’ll do once they have it. A number of population-based studies have found that obesity during adolescence significantly increases a person’s risk of MS. For example, in the EnvIMS study, which looked at factors in the environment that increase MS risk, a larger body size at age 25 was associated with a two-fold increased risk of MS in men, and a similarly increased risk in women (Wesnes and colleagues. Mult Scler 2015;21:388-395). This link between obesity and MS appears to start during adolescence (Hedstrom and colleagues. Mult Scler 2015; epublished September 11, 2015). A study by the New York State MS Consortium also found that among women with MS, those with a higher body weight either at puberty or at age 25 developed MS symptoms at a younger age (Kavak and colleagues. Mult Scler 2015;21:858-865).
Several theories have been suggested to explain the connection between obesity and MS. Fat tissue in our bodies isn’t an inert substance (although it seems to be). It releases a number of substances (called adipokines; sometimes referred to as fat tissue-derived hormones) that act as signalling molecules in the body (Versini and colleagues. Autoimmun Rev 2014;13:981-1000). One effect of this signalling is to promote a low-grade inflammation, which can have important consequences among people with autoimmune disorders – most importantly, MS and rheumatoid arthritis. This may also explain why people with one autoimmune disorder have a higher risk of developing another autoimmune disorder, such as psoriasis, thyroid disease and inflammatory bowel disease.
It isn’t known if this low-level inflammation is sufficient on its own, or whether it works in concert with other MS risk factors. Recent studies have found that obesity interacts with infectious mononucleosis (“mono”) to increase the risk of developing MS during the teen years (Hedstrom and colleagues. Eur J Neurol 2015;22:578). There has also been the suggestion that genetic factors (the HLA-DRB1*15 genotype) interact with obesity to increase the MS risk (Hedstrom and colleagues. Neurology 2014;82:865-872).
But there may be other factors involved. Dietary choices will affect the populations of bacteria that normally reside in your gastrointestinal tract. Some food choices will cause a shift to a more inflammatory profile, which in turn can promote inflammation in the brain and spinal cord (Maranduba and colleagues. J Immunol Res 2015;2015:931574). So oereating may contribute to this. Unfortunately, the research is still preliminary so there are no firm recommendations yet about the best MS-friendly foods.
In addition, one study found that among people with MS taking an interferon-beta medication (Avonex, Rebif, Betaseron/Extavia), those who were overweight or obese had more inflammatory activity on their brain MRI compared to those who were normal weight. (Overweight is generally defined as a body-mass index [BMI] higher than 25, which corresponds to a 6-foot tall man [183 cm] weighing more than 185 lbs [84 kg], or a 5-foot 4-inch woman [163 cm] weighing more than 146 lbs [66 kg].) The proportion of people who had no evidence of disease activity (no relapses, MRI activity or disability progression) was two-fold higher among those with normal weight compared to those who were overweight/obese (Kvistad and colleagues. J Neuroimmunol 2015;288:92-97). This lesser drug effect with obesity may simply be due to the same amount of drug distributing through a larger volume of body tissue (an effect also seen with Tysabri).
An Australian study also found that MS-related disability was significantly higher among people with obesity (Tettey and colleagues. Neuroepidemiology 2016; epublished January 16, 2016). However, it isn’t clear if this is because of the effects of fat tissue on MS, or the greater difficulty getting around because of obesity.
Taken together, these findings suggest shedding a few pounds won’t just enhance fitness and feeling good. It may also have a beneficial impact on the MS disease process itself.
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