Letter: Linoleic acid in multiple sclerosis

Dietary interventions for multiple sclerosis-related outcomes

BACKGROUND

Multiple sclerosis (MS) is a common demyelinating disease of the central nervous system. Although the exact pathogenesis remains unknown, the leading theory is that it results from immune system dysregulation. Approved disease-modifying therapy appears to modulate the immune system to improve MS-related outcomes. There is substantial interest in the ability of dietary interventions to influence MS-related outcomes. This is an update of the Cochrane Review 'Dietary interventions for multiple sclerosis' (Farinotti 2003; Farinotti 2007; Farinotti 2012).

OBJECTIVES

To assess the effects of dietary interventions (including dietary plans with recommendations for specific whole foods, macronutrients, and natural health products) compared to placebo or another intervention on health outcomes (including MS-related outcomes and serious adverse events) in people with MS.

SEARCH METHODS

On 30 May 2019, we searched CENTRAL, MEDLINE, Embase, and Web of Science. We also searched ClinicalTrials.gov, World Health Organization International Clinical Trials Registry Platform (ICTRP), and Networked Digital Library of Theses and Dissertations (NDLTD). We checked reference lists in identified trials and requested information from trial authors to identify any additional published or unpublished data.

SELECTION CRITERIA

We included any randomized controlled trial (RCT) or controlled clinical trial (CCT) examining the effect of a dietary intervention versus placebo or another intervention among participants with MS on MS-related outcomes, including relapses, disability progression, and magnetic resonance imaging (MRI) measures.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. Planned primary outcomes were number of participants experiencing relapse and change in disability progression, according to a validated disability scale at the last reported follow-up. Secondary outcomes included MRI activity, safety, and patient-reported outcomes. We entered and analysed data in Review Manager 5.

MAIN RESULTS

We found 41 full-text articles examining 30 trials following full-text review. Participants were adults with MS, defined by established criteria, presenting to MS clinics in Europe, North America, and the Middle East. Study design varied considerably, although all trials had at least one methodological issue leading to unknown or high risk of bias. Trials examined: supplementation to increase polyunsaturated fatty acids (PUFAs) (11 trials); a variety of antioxidant supplements (10 trials); dietary programmes (3 trials); and other dietary supplements (e.g. acetyl L-carnitine, biotin, creatine, palmitoylethanolamide, probiotic, riboflavin) (6 trials). In three trials comparing PUFAs with monounsaturated fatty acids (MUFAs), the evidence was very uncertain concerning difference in relapses (risk ratio (RR) 1.02, 95% confidence interval (CI) 0.88 to 1.20; 3 studies, 217 participants; 75% in the PUFA group versus 74% in the MUFA group; very low-certainty evidence). Among four trials comparing PUFAs with MUFAs, there may be little to no difference in global impression of deterioration (RR 0.85, 95% CI 0.71 to 1.03; 4 studies, 542 participants; 40% in the PUFA group versus 47% in the MUFA group; low-certainty evidence). In two trials comparing PUFAs with MUFAs (102 participants), there was very low-certainty evidence for change in disability progression. None of the PUFA versus MUFA trials examined MRI outcomes. In one trial comparing PUFAs with MUFAs (40 participants), there were no serious adverse events; based on low-certainty evidence. In two trials comparing different PUFAs (omega-3 versus omega-6), there may be little to no difference in relapses (RR 1.02, 95% CI 0.62 to 1.66; 2 studies, 129 participants; 30% in the omega-3 versus 29% in the omega-6 group; low-certainty evidence). Among three trials comparing omega-3 with omega-6, there may be little to no difference in change in disability progression, measured as mean change in Expanded Disability Status Scale (EDSS) (mean difference (MD) 0.00, 95% CI -0.30 to 0.30; 3 studies, 166 participants; low-certainty evidence). In one trial comparing omega-3 with omega-6, there was likely no difference in global impression of deterioration (RR 0.99, 95% CI 0.51 to 1.91; 1 study, 86 participants; 29% in omega-3 versus 29% in omega-6 group; moderate-certainty evidence). In one trial comparing omega-3 with omega-6 (86 participants), there was likely no difference in number of new T1- weighted gadolinium-enhancing lesions, based on moderate-certainty evidence. In four trials comparing omega-3 with omega-6, there may be little to no difference in serious adverse events (RR 1.12, 95% CI 0.38 to 3.31; 4 studies, 230 participants; 6% in omega-3 versus 5% in omega-6 group; low-certainty evidence). In four trials examining antioxidant supplementation with placebo, there may be little to no difference in relapses (RR 0.98, 95% CI 0.59 to 1.64; 4 studies, 345 participants; 17% in the antioxidant group versus 17% in the placebo group; low-certainty evidence). In six trials examining antioxidant supplementation with placebo, the evidence was very uncertain concerning change in disability progression, measured as mean change of EDSS (MD -0.19, 95% CI -0.49 to 0.11; 6 studies, 490 participants; very low-certainty evidence). In two trials examining antioxidant supplementation with placebo, there may be little to no difference in global impression of deterioration (RR 0.99, 95% 0.50 to 1.93; 2 studies, 190 participants; 15% in the antioxidant group versus 15% in the placebo group; low-certainty evidence). In two trials examining antioxidant supplementation with placebo, the evidence was very uncertain concerning difference in gadolinium-enhancing lesions (RR 0.67, 95% CI 0.09 to 4.88; 2 studies, 131 participants; 11% in the antioxidant group versus 16% in the placebo group; very low-certainty evidence). In three trials examining antioxidant supplementation versus placebo, there may be little to no difference in serious adverse events (RR. 0.72, 95% CI 0.17 to 3.08; 3 studies, 222 participants; 3% in the antioxidant group versus 4% in the placebo group; low-certainty evidence).

AUTHORS' CONCLUSIONS

There are a variety of controlled trials addressing the effects of dietary interventions for MS with substantial variation in active treatment, comparator, and outcomes of interest. PUFA administration may not differ when compared to alternatives with regards to relapse rate, disability worsening, or overall clinical status in people with MS, but evidence is uncertain. Similarly, at present, there is insufficient evidence to determine whether supplementation with antioxidants or other dietary interventions have any impact on MS-related outcomes.

Dietary interventions for multiple sclerosis

BACKGROUND

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).

OBJECTIVES

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?

SEARCH METHODS

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.

SELECTION CRITERIA

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.

DATA COLLECTION AND ANALYSIS

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.

MAIN RESULTS

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.

AUTHORS' CONCLUSIONS

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.

Dietary interventions for multiple sclerosis

BACKGROUND

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.

OBJECTIVES

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.

SEARCH STRATEGY

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.

SELECTION CRITERIA

All randomised controlled trials comparing a specific dietary intervention, diet plan or dietary supplementation, with no dietary modification or placebo, were eligible.

DATA COLLECTION AND ANALYSIS

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.

MAIN RESULTS

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.

AUTHORS' CONCLUSIONS

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.

Red blood cell and adipose tissue fatty acids in mild inactive multiple sclerosis

The fatty acid profiles of phosphatidyl ethanolamine (PE) and phosphatidyl choline (PC) of the red blood cells of 30 patients with mild inactive multiple sclerosis (MS) and 30 healthy controls were studied by gas chromatography. The groups were well matched for factors likely to influence tissue lipid levels, including diet. The MS patients showed a significant reduction in PE eicosapentaenoic acid (p = 0.009) especially in women, and an increase in both PE dihomo-gamma-linolenic acid (p = 0.004) and PC stearic acid (p = 0.04). No reduction in linoleic acid was observed in either the PC or PE fractions of the MS subjects. A similar study of the fatty acid profile in adipose tissue in 26 MS and 35 healthy controls found no detectable eicosapentaenoic acid in either group. However, whereas docosahexaenoic acid was not detectable in any MS patient, 40% of the controls had measurable levels varying from to 0.1 to 0.3% of total estimated fatty acid (p = 0.0003). No reduction in linoleic acid in MS subjects was observed. Supplementation with oral fish body oil demonstrated that n-3 fatty acids were incorporated into red blood cells over 5 weeks and this occurred equally in MS and controls. The effects of oral supplementation on adipose tissue were studied after 1 and 2 years. Whereas many fatty acids such as linoleic acid were raised at 1 year, but did not rise subsequently, eicosapentaenoic acid and docosahexaenoic acid continued to rise through the 2-year period.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma lipids and their fatty acid composition in multiple sclerosis

We report an extensive study of the plasma lipid profile and fatty acid composition in 61 multiple sclerosis (MS) patients compared with 61 normal subjects. The main abnormality in the MS was a reduction in the proportion of linoleic and arachidonic acids mostly evident in the HDL and in the cholesteryl esters fraction, with a compensatory increase in saturated acids. The fatty acid abnormalities correlated with the duration of the disease and the degree of disability. Thus, in the MS patients studied there was a deficiency in essential fatty acids, although this metabolic abnormality does not seem specific to MS.

Linoleate and fatty acid compositions in the serum lipids of Japanese patients with multiple sclerosis

Serum fatty acid compositions were determined in 21 Japanese patients with multiple sclerosis and 14 neurological controls. No statistical difference was found either for linoleic acid or for arachidonic acid between the 2 groups. It may be that neither serum linoleic acid nor arachidonic acid is inevitably associated with the pathogenesis of multiple sclerosis.

Stimulation of immune reactivity by methoxy-substituted glycerol ethers incorporated into the feed

In mice, the plaque-forming cell response to sheep red blood cells was stimulated by a mixture of methoxy-substituted glycerol ethers isolated from Greenland shark liver oil and by synthetic 1-0-(2-methoxyhexadecyl)-glycerol, given in the diet. In preliminary experiments, this synthetic compound also increased the ability of parental spleen cells to induce graft-vs.-host reactions in F1 hybrid mice. Glycerol ethers occur in the bone marrow fat of mammals and in the membrane phospholipids. It is postulated that the methoxy-substituted glycerol ethers supplied in the diet may stimulate the bone marrow and/or may be incorporated into membrane lipids, thereby changing the structure and function of the membranes.

Linoleic acid in multiple sclerosis: failure to show any therapeutic benefit

We have studied the effect of a dietary supplement with linoleic acid (LA) in 76 patients with MS. We could detect no effect of this supplement on the progression of neurological findings, the relapse rate, or the severity of relapses. We were also able to show that oral supplementation with a linoleic acid preparation would raise the blood level of LA in these patients. We were unable to show that there was any reduction in the linoleic acid blood levels associated with acute relapses of MS during this study.

Phytohaemagglutinin stimulation of human lymphocytes: effect of fatty acids on uridine uptake and phosphoglyceride fatty acid profile

1. When added to cultures of human peripheral lymphocytes, saturated (palmitate, stearate, heptadecanoate) and unsaturated (oleate, linoleate, arachidonate) fatty acids bound to albumin at an acid-albumin ratio of 2:1, inhibited the phytohaemaegglutinin-stimulated uptake of [14C]-uridine. Uridine uptake in unstimulated cells was not affected by any of these fatty acids. 2. When saturated and unsaturated acids were present simultaneously in the incubation mixture the inhibit but relieved the inhibitory effects of both saturated and unsaturated fatty acids. 4. Stimulated and unstimulated cells incorporated exogenous fatty acids into membrane phosphoglycerides. Details of the fatty acid profiles are given. 5. Evidence is presented that the inhibition results, at least in part, from modification of phosphoglyceride fatty acid profile.

Relationship between plasma and lymphocyte linoleate in multiple sclerosis

The linoleate level in total lipids was measured in lymphocytes from control subjects and patients with multiple sclerosis. A small but significant decrease was found in cases of multiple sclerosis. The percentage composition of lymphocyte fatty acids was determined in rats fed diets with various linoleate contents. There was a correlation between lymphocyte linoleate and plasma linoleate in both humans and rats.