Dietary interventions for multiple sclerosis

Clinical and experimental data suggest that certain dietary regimens, particularly those including polyunsaturated fatty acids (PUFAs) and vitamins, might improve outcomes in people with multiple sclerosis (MS). Diets and dietary supplements are much used by people with MS in the belief that they might improve disease outcomes and overcome the effectiveness limits of conventional treatments.This is an update of the Cochrane review "Dietary intervention for multiple sclerosis" (first published on The Cochrane Library 2007, Issue 1).

To answer MS patients' questions regarding the efficacy and safety of dietary regimens for MS. Can changes in dietary habits be an effective intervention for MS patients? Are the potential side effects of these interventions known, and have they been measured? Are potential interactions between dietary interventions and other curative or symptomatic treatments known and have they been studied?

We searched the Cochrane Multiple Sclerosis and Rare Diseases of the Central Nervous System Group Specialised Register (November 2011), CENTRAL (The Cochrane Library 2011, Issue 4), MEDLINE (PubMed) (1966 to November 2011), EMBASE (embase.com) (1974 to November 2011) and reference lists of papers found.

All controlled trials (randomised controlled trials (RCTs) and controlled clinical trials (CCTs)) on a specific dietary intervention, diet plan or dietary supplementation, except for vitamin D supplementation, compared to no dietary modification or placebo were eligible.

Two review authors independently selected articles, assessed trial quality and extracted data. Data were entered and analysed in RevMan.Dichotomous data were summarised as relative risks (RR) with 95% confidence intervals (95% CI) using a random-effects model in the presence of heterogeneity (I² > 60%). Continuous data were analysed using weighted mean differences, determined by the difference between the pre- and post-intervention changes in the treatment and control groups.

Six RCTs that investigated PUFAs emerged from the search strategy, accounting for 794 randomised patients.PUFAs did not have a significant effect on disease progression at 24 months. Omega-6 fatty acids (11 to 23 g/day linoleic acid) didn't show any benefit in 144 MS patients (RR 1.04, 95% CI 0.66 to 1.63). Linoleic acid (2.9 to 3.4 g/day) had no benefit in 65 chronic progressive MS patients (RR 0.78, 95% CI 0.43 to 1.42). Omega-3 fatty acids had no benefit in 292 relapsing remitting MS patients (RR 0.82, 95% CI 0.65 to 1.03, P = 0.08).Slight potential benefits in relapse outcomes were associated with omega-6 fatty acids in some studies, however these findings were limited by the reduced validity of the endpoints. No judgements about safety or patient-reported outcomes were possible. In general, trial quality was poor.No studies on vitamin supplementation and allergen-free diets were analysed as none met the eligibility criteria, mainly due to lack of clinical outcomes.

PUFAs seem to have no major effect on the main clinical outcome in MS (disease progression), but they may tend to reduce the frequency of relapses over two years. However, the data that are available are insufficient to assess a real benefit or harm from PUFA supplementation because of their uncertain quality.Evidence on the possible benefits and risks of vitamin supplementation and antioxidant supplements in MS is lacking. More research is required to assess the effectiveness of dietary interventions in MS.