Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system in which the immune system attacks myelin (the protective sheath of nerve fibers), causing demyelinating plaques and resulting in slowed or interrupted nerve conduction. It affects approximately 130,000 people in Italy (prevalence increasing: 260/100,000 in some northern regions). There is no cure, but available immunomodulatory treatments (interferon beta, glatiramer acetate, natalizumab, ocrelizumab, fingolimod, and many others) have dramatically reduced relapse frequency and disability progression. The role of diet in MS is an active but still largely inconclusive research field: no diet has demonstrated in controlled studies the ability to alter the disease course. However, some nutritional strategies show evidence of benefit on symptoms, quality of life, and associated risk factors.

Vitamin D in MS: The Strongest Evidence

Vitamin D is the nutrient with the strongest evidence for a role in MS. Epidemiological data: MS prevalence increases with latitude (less sun, less vitamin D produced in the skin). Populations with high sun exposure have low MS incidence. People with MS have on average lower vitamin D levels than the general population. Longitudinal studies show that low vitamin D levels at diagnosis are associated with higher relapse frequency and faster progression. Clinical trials: the SOLAR trial (2019, Smolders et al.) and the EVIDIMS trial (2021) on high-dose vitamin D3 supplementation in relapsing MS did not demonstrate significant relapse reduction compared to placebo at standard doses of immunomodulatory drugs. However, observational studies consistently show benefit. The position of ECTRIMS guidelines: vitamin D supplementation (2,000–4,000 IU/day) is recommended to maintain blood levels of 25-OH vitamin D between 40 and 60 ng/mL, both for potential effects on MS and for bone health benefits (MS is associated with increased osteoporosis risk due to reduced physical activity and corticosteroid use). Moderate sun exposure is recommended, avoiding overheating (heat temporarily worsens MS symptoms through the Uhthoff phenomenon).

The Protective Dietary Pattern: Available Evidence

Recent research on nutrition in MS has focused on overall dietary patterns rather than individual nutrients. Mediterranean diet: an observational study by Stoiloudis et al. (2022, on 563 MS patients) shows that adherence to the Mediterranean diet is associated with less fatigue, reduced disability, and better quality of life. A randomized pilot trial (Wahls 2019) is underway evaluating the Wahls diet (a paleo diet variant rich in vegetables) versus low saturated fat diet versus control. Omega-3 fatty acids: in vitro and animal model studies show neuroprotective effects of omega-3s (EPA and DHA) through reduction of pro-MS inflammatory mediators. Clinical studies in human MS are limited and show preliminary positive but inconclusive results. Fish oil supplementation (1–2 g of EPA+DHA daily) is considered safe and potentially beneficial. Microbiome and MS: intestinal dysbiosis is documented in MS. The intestinal microbiome modulates the immune system through gut-brain axis mechanisms. Pilot studies of FMT and specific probiotics in MS are underway (NCT04397588, NCT04082910). Probiotics (Lactobacillus acidophilus, Bifidobacterium animalis) in small studies show reduced systemic inflammation in MS patients: not yet sufficient for clinical recommendations, but research is promising.

Managing MS Symptoms with Diet

Beyond effects on disease progression, diet can help manage various MS symptoms. Fatigue (the most common MS symptom): fatigue in MS is complex (primary fatigue from neurological damage plus secondary fatigue from inactivity, sleep disorders, anemia, thyroid dysfunction). Dietary strategies for fatigue: maintaining normal weight (overweight worsens fatigue), low glycemic index diet (avoiding postprandial blood sugar spikes that cause drowsiness), adequate hydration (dehydration worsens fatigue), adequate iron and B12 (ruling out deficiency as a cause of fatigue before attributing it to MS). Constipation: very common in MS due to compromised autonomic intestinal innervation and reduced physical activity. Dietary management: adequate fiber (25–35 g/day), adequate hydration (2 liters/day), probiotics (Lactobacillus, Bifidobacterium). Bladder dysfunction: reducing fluid intake to reduce urinary frequency is counterproductive (increases UTI risk). Maintain adequate hydration (6–8 glasses of water daily) and reduce caffeine and alcohol (diuretics and bladder irritants). Dysphagia: may be present in advanced MS forms. Management as in the dysphagia section (article 342).

The Wahls Diet: Critical Analysis

The Wahls diet is a diet developed by Dr. Terry Wahls (a physician with primary progressive MS) who claims to have significantly improved her disability through a diet specifically designed to support mitochondrial function. Wahls diet principles: 9 servings of vegetables daily (3 of leafy greens, 3 of colored vegetables, 3 of sulfur-containing vegetables like cabbage and onions), significant amounts of grass-fed meat, wild fish, pasture-raised eggs, elimination of grains, legumes, dairy, nightshades (tomatoes, potatoes, peppers, eggplants). It is essentially a modified paleo diet. Scientific evidence: Terry Wahls published a small open pilot trial (uncontrolled: Wahls, Darling et al., 2014, 20 patients) showing fatigue improvement. A randomized controlled trial (Wahls versus low saturated fat diet versus control) is underway (Wahls 2019, NCT02918175: results expected 2025). Critical analysis: the Wahls diet is very restrictive and difficult to maintain. The exclusion of legumes and whole grains is hardly justified by current evidence. The enrichment in vegetables and omega-3s is almost certainly beneficial. Recommendation: do not adopt the Wahls diet in its full version without supervision by a dietitian and neurologist. Adopting healthy principles (more vegetables, omega-3s, reduced saturated fat) is certainly reasonable.

MS and Weight: Managing Excess Weight

Obesity is a risk factor for MS (increases the risk of developing it in young people: OR 2.0 for adolescent obesity) and in those who already have MS worsens disability and progression. Weight reduction in MS: improves fatigue (reduces metabolic load), improves functional mobility (reduces weight to move during walking), reduces systemic inflammation (adipose tissue is a source of pro-inflammatory cytokines), improves response to immunomodulatory drugs (some drugs have pharmacokinetics influenced by body weight). The opposite risk: malnutrition in advanced MS forms. Dysphagia, fatigue that makes cooking difficult, reduced physical activity (risk of sarcopenic muscle loss) can lead to malnutrition. BMI and body composition monitoring (BIA) is recommended in MS follow-up. Italian resources for MS: AISM (Italian Multiple Sclerosis Association, aism.it) has specific nutritional guides, adapted cooking courses, and support for people with MS. The Italian Multiple Sclerosis Foundation (FISM) funds research on nutrition in MS.