Dietary interventions for multiple sclerosis

Abstract

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. We performed a Cochrane review of all randomised trials of dietary regimens for MS with the aim of answering MS consumers' questions regarding the efficacy and safety of these interventions. We searched the Cochrane MS Group trial register (February 2006), Cochrane Central Register of Controlled Trials (CENTRAL), Cochrane Library, Issue 1, 2006, MEDLINE (PubMed) (1966 to March 2006), EMBASE (1974 to March 2006) and the bibliographies of papers found. All randomised controlled trials comparing a specific dietary intervention, diet plan or dietary supplementation, with no dietary modification or placebo, were eligible. Two reviewers independently selected articles, assessed trial quality and extracted data. Trial quality was poor, particularly as regards descriptions of randomisation, blinding and adverse event reporting. Some studies had large numbers of drop-outs; dropouts were never included in the analyses. PUFAs did not have a significant effect on disease progression, measured as worsening of Disability Status Scale. Omega-6 fatty acids (11-23 g/day linoleic acid) had no benefit in 75 relapsing remitting (RR) MS patients (progression at two years: relative risk (RR)=0.78, 95% CI [0.45 to 1.36]) or in 69 chronic progressive (CP) MS patients (RR=1.67, 95% CI [0.75 to 3.72]. Linoleic acid (2.9-3.4 g/day) had no benefit in CPMS (progression at two years: RR=0.78, 95% CI [0.43 to 1.42]). Slight decreases in relapse rate and relapse severity were associated with omega-6 fatty acids in some small studies, however these findings are limited by the limited validity of the endpoints.Omega-3 fatty acids had no benefit on progression at 12 months in 14 RRMS patients or at 24 months in 292 RRMS patients (RR=0.15, 95% CI [0.01 to 3.11], p= 0.22 at 12 months, and 0.82 95% CI [0.65 to 1.03], p=0.08, at 24 months). The low frequency of reported adverse events suggests no major toxicity associated with PUFA administration. No studies on vitamin supplementation and allergen-free diets were analysed as none met the eligibility criteria. PUFAs seem to have no major effect on the main clinical outcome in MS (disease progression), and does not substantially affect the risk of clinical relapses over 2 years. However, the data available are insufficient to assess any potential benefit or harm from PUFA supplementation. Evidence bearing 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 diets interventions in MS.