How does your diet affect MS? – Part 1
Over the past 50 years, many people have speculated that changing your diet can change your MS and countless cookbooks offer recipes for success. But what can research tell us about the impact of diet on the MS disease process?
Theories about diet and MS are largely based on two observations. The first is that MS is more common in North America and northern Europe. While this is attributed to genetic and environmental factors such as sun exposure, some have suggested that the Western diet – high calories, high fat – plays a role as well. And although MS is less common in Asia, the increasing incidence of MS in Asian countries may be due in part to the Asian diet becoming more westernized. As you might expect, this is very difficult to establish because of the many other factors – improvements in diagnosis, less sun exposure, smoking – that could contribute to the frequency of MS.
The second observation dates back to the 1940s when Dr. Roy Swank found that the rate of MS was higher among Norwegians living on farms compared to those living in fishing villages (Swank RL. Am J Med Sci 1950;220:421-430; Swank and colleagues. N Engl J Med 1952;246:722-728). He attributed this difference to diet: people living inland consumed higher amounts of butterfat whereas people on the coast tended to eat more fish.
This observation was really two. The first is that high amounts of fish oils in the diet may reduce the risk of MS – which has led to the interest in the omega-3 fatty acids found in fish. The second is that high amounts of butterfat may increase the risk of developing MS.
Fish and buttermilk came to the fore again in the 1990s with an analysis that looked at MS cases in relation to social and demographic factors in the U.S (Lauer K. J Clin Epidemiol 1994;47:43-48). The study found that people who were more affluent (better nutrition, higher consumption of meat) were more likely to develop MS. And people with diets low in fish and high in dairy products also seemed to be at higher risk.
Fish oil and buttermilk were the starting points of what would be known as the Swank diet. Dr. Swank promoted the idea of a diet that was low in saturated fats – no meat in the first year – and polyunsaturated fats, and high in grains, fruits and vegetables. This, he claimed in a follow-up article over fifty years after his initial report, leads to a longer, healthier life for people with MS (Swank & Goodwin. Nutrition 2003;19:161-162). Dr. Swank was his own best advertisement – he died just shy of 100. And over the years he published some thirty articles promoting the benefits of his diet. Unfortunately, he never tested the diet in a rigorous, scientific way – nor did his work inspire anyone else to research it. It isn’t hard to imagine that people (with or without MS) will live longer if they restrict their intake of meat, fast foods and other things we know are bad for you. But that doesn’t mean that the diet provides specific benefits in MS.
The same can be said for the Evers diet, named after Dr. Joseph Evers, a German doctor who promoted the idea of uncooked natural foods and wheat germ (Uhlemann HJ. Dtsch Med Wochenschr 1951;76:1212-1214). Salt and sugar were verboten; wine and brandy were permitted. But again, this diet has never been scientifically studied.
However, this focus on nutrition did spark research into the possible effects of dietary fat on MS. Of particular interest were two polyunsaturated fatty acids (PUFAs): omega-3, which is mainly found in fish; and omega-6, which is found mainly in plants. PUFA research has focused on two key questions: do these dietary factors have an effect on the immune system; and can they be used as an actual treatment, i.e. do they provide any benefits with respect to MS symptoms or the disease course?
Omega-3 fatty acids include ALA (alpha-linolenic acid), EPA (eicosapentaenoic acid) and DHA (docosahexanoic acid). They’re found in fatty fish, such as salmon, herring, sardines, mackerel, tuna and cod liver, as well as in supplements such as cod liver oil. Omega-6 fatty acids are found mainly in oils (sunflower, rapeseed, soybean, palm oil) but can also be found in poultry, eggs, nuts and whole-grain breads. Alternative sources are evening primrose oil and spirulina.
Studies in the 1960s and 1970s suggested that PUFAs could modulate the immune response in MS, and it was hypothesized that dietary supplementation could correct the abnormal T cell response seen in MS (Field & Shenton. Acta Neurol Scand 1975;52:121-136; Horrobin and colleagues. Med Hypotheses 1979;5:969-985). One doctor started a routine of giving his patients sunflower seed oil, and his impression was that it did some good. It wasn’t scientific but it was a start and led to one of the first double-blind studies in 1973 (Millar and colleagues. Br Med J 1973;1:765-768). While nothing definitive was shown with respect to progression of disability, sunflower seed oil appeared to reduce the frequency, severity and duration of MS relapses. A second study also found that high doses of sunflower seed oil seemed to reduce the severity and duration of relapses (Bates and colleagues. Br Med J 1978;2:1390-1391), but a third study did not (Paty DW. Arch Neurol 1983;40:693-694. The combined result suggested that sunflower seed oil seemed to reduce the severity and duration of relapses, and even had a small effect on disability progression in people with minimal disability (Dworkin and colleagues. Neurology 1984;34:1441-1445).
But enthusiasm for the beneficial effects of PUFAs on MS dimmed somewhat in the subsequent thirty years. A study of omega-3s (EPA/DHA capsules) found a very small effect on relapses, but the results weren’t significant (Bates and colleagues. J Neurol Neurosurg Psychiatry 1989;52:18-22). A one-year study of fish oil supplements found only modest effects on relapse rates (Weinstock-Guttman and colleagues. Prostaglandins Leukot Essent Fatty Acids 2005;73:397-404). People did say they felt better on the supplements but this effect was largely gone after a year. A small study in Norway suggested that omega-3 supplements and an improved diet helped to improve relapses and progression in people newly-diagnosed with MS (Nordvik and colleagues. Acta Neurol Scand 2000;102:143-149). In contrast, the OFAMS study of people on Rebif found there was no added benefit on relapses, MRI or other measures when omega-3 supplements were used (Torkildsen and colleagues. : Arch Neurol 2012;69:1044-1051).
Taking all these studies together, it seems that omega-3 or omega-6 supplements are unlikely to have an effect on the progression of disability in MS, although there may be small effects on relapses (Farinotti and colleagues. Cochrane Database Syst Rev 2012 Dec 12;12:CD004192).
Does this mean that PUFAs provide no benefit in MS? Not necessarily. It may be a little much to expect that any dietary supplement will act as an actual treatment. Foods generally don’t have drug-like effects and aren’t “dosed” at pharmaceutical levels. But there’s probably enough evidence at the moment to support the use of supplements to give a small boost to fighting MS relapses.
If you do decide to use omega-3 or omega-6 supplements, there’s little to guide you on the best dose (Stewart & Bowling. Int MS J 2005;12:88-93). For omega-3s, it’s probably best not to exceed a daily dose of 3 grams of EPA/DHA because higher doses can cause side effects, such as diarrhea and nausea. Other side effects can include belching, fish breath and heartburn. Caution is needed if you’re planning to have surgery or you’re taking a blood-thinning medication (e.g. warfarin or an antiplatelet drug) because omega-3s can slow the time to takes for your blood to clot. This may cause more nosebleeds in some people. Omega-3s can also cause breathing problems in people who are sensitive to Aspirin (acetylsalicylic acid, or ASA). Omega-3s can cause vitamin E deficiency, so you may need to take low-dose vitamin E supplements as well. In general, supplements may be better than trying to obtain that much omega-3 from your diet – about 2 servings of fish daily – because of concerns about mercury contamination in fish.
For omega-6, the dose of sunflower seed oil in studies was typically less than 23 grams per day (Millar 1973). For evening primrose oil, the dose is usually 2-4 grams per day. Alternatively, you can try flaxseed oil (1 tablespoon daily), spirulina (3-10 grams daily), or blackcurrant seed oil (1 gram per day). As with omega-3s, omega-6 is associated with a risk of bleeding and may cause diarrhea and vitamin E deficiency. There’s also a risk of seizures in people with epilepsy or during anesthesia. Be careful about the source of supplements. Spirulina can be contaminated with heavy metals or germs, which can cause nausea/vomiting and liver toxicity (Stewart & Bowling 1973).
The long-term safety of omega-3/omega-6 hasn’t been studied. There have been concerns that linoleic acid may increase the risk of developing ulcerative colitis (EPIC Study. Gut 2009;58:1606-1611), and may cause problems in women with polycystic ovary syndrome (Kasim-Karakas and colleagues. J Clin Endocrinol Metab 2004;89:615-620). So it’s best to consult with a dietitian before embarking on a long-term course of PUFA supplements.
Early dietary research also flagged buttermilk as a potential problem in MS. We’ll look at whether drinking milk has an impact on MS in Part 2.
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