Certain diets may support cognition in people with multiple sclerosis, although the evidence remains too limited for firm recommendations.
Studies of the low-fat Swank and Wahls diets reported improvements in processing speed and self-perceived cognitive function.
Evidence for the Mediterranean diet was mixed, while small studies suggested possible benefits from ketogenic diets and time-restricted eating.
The researchers wrote: “Dietary interventions may hold promise as adjunctive strategies for cognitive health in MS; however, inconsistencies in study designs, cognitive measures, and intervention duration, combined with limited high-quality evidence, undermine strong recommendations, which warrant further evaluations.”
Cognitive difficulties affect an estimated 40 per cent to 70 per cent of people living with MS.
MS is a long-term immune-mediated condition that causes inflammation and damage in the brain and spinal cord, disrupting communication between nerve cells.
Information processing speed is the area of cognition most commonly affected. People with MS may also experience difficulties with memory, attention, learning and executive function.
Executive function refers to the mental skills used for planning, organising and solving problems.
These changes can affect work, social activities, adherence to treatment and overall quality of life.
Disease-modifying therapies can reduce relapses and slow the progression of disability, but few treatments specifically target cognitive decline.
No diet can cure MS or replace disease-modifying therapies. However, healthy eating may help ease symptoms and slow disease progression, prompting researchers to examine whether certain diets could support cognitive health alongside treatment.
A team led by researchers in Iran reviewed studies identified in searches conducted up to 20 September 2025.
Sixteen studies, reported across 18 scientific papers, met the inclusion criteria.
Five were randomised controlled trials, meaning participants were randomly assigned to dietary interventions or comparison groups.
Four were non-randomised intervention studies and seven were observational studies. Most interventions lasted between eight weeks and one year.
The Mediterranean diet was among the approaches studied most frequently. It is rich in fruit, vegetables, whole grains, legumes, fish and olive oil.
Studies also assessed the Wahls diet, a modified Paleo-style approach that emphasises vegetables, fruit and high-quality proteins while excluding grains, legumes, eggs, dairy products and processed foods.
The Swank diet places strict limits on saturated fat while encouraging whole grains, fruit and vegetables.
Other intervention studies examined ketogenic diets, which are very low in carbohydrates and high in fat, and time-restricted eating, which limits food intake to a set period each day.
Researchers also assessed an app-based nutrition programme designed to increase fruit and vegetable intake.
Several observational studies examined broader links between healthy eating patterns and cognitive outcomes in people with MS.
Studies of the Wahls and Swank diets reported improvements in processing speed and self-perceived cognitive function.
A randomised trial comparing the two diets found similar improvements in both groups, suggesting that features shared by the approaches may matter more than the specific diet followed.
However, the evidence remained limited.
Findings for the Mediterranean diet were mixed.
Two randomised clinical trials found no significant improvements in cognitive performance compared with control diets.
However, a more recent trial reported better processing speed and manual dexterity among overweight participants following three calorie-restricted Mediterranean diets.
Observational studies also linked closer adherence to the Mediterranean diet with fewer cognitive complaints and better processing speed.
Small studies suggested possible cognitive benefits from ketogenic diets and time-restricted eating, but the evidence was too limited and inconsistent to support firm conclusions.
Findings for generally healthy diets and higher-fibre eating patterns were also inconsistent.
Some observational studies linked healthier diets or higher fibre intake with fewer cognitive complaints, while others found no association.
The researchers wrote: “This systematic review suggests that dietary interventions may offer benefits for cognitive outcomes in MS, particularly in processing speed and self-perceived cognitive function.”
They cautioned that “the certainty of evidence is limited” because many studies were small, used different dietary interventions and cognitive assessments, had relatively short follow-up periods or were observational.
The team concluded: “Well-powered, methodologically rigorous randomised controlled trials with standardised cognitive outcome measures are required before firm clinical recommendations can be made.”
