Mediterranean diet may significantly lower Multiple Sclerosis risk, especially in younger adults and nonsmokers, Swedish study finds

A new large-scale prospective study suggests that adhering to a Mediterranean diet could substantially lower the risk of developing multiple sclerosis (MS), with the greatest protective effect observed in nonsmokers and people under 45. The study was published online on December 15 in the Multiple Sclerosis Journal.

According to the Medscape website, even small increases in the Mediterranean Diet Score cut MS risk by 14 percent overall, 26 percent in nonsmokers, and 23 percent in under-45s.

“As the decreased MS risk is particularly evident among younger adults, we have to encourage healthy dietary habits early on as this can decrease the risk of disease onset,” lead author Sara Ratti, Department of Statistics and Quantitative Methods, University of Milano-Bicocca, Milan, said.

What is multiple sclerosis(MS)?

Multiple sclerosis (MS) is a long-term condition affecting the central nervous system, marked by inflammation, nerve damage, and the loss of myelin, the protective sheath around nerve fibers. The disease typically begins between ages 20 and 45, with age and smoking identified as major risk factors.

The Mediterranean diet, rich in fruits, vegetables, grains, olive oil, and omega-3s, is associated with lower risks of Alzheimer’s and Parkinson’s, likely due to its antioxidant and anti-inflammatory properties.

Earlier studies indicated the Mediterranean diet might reduce MS risk, but their limited case-control designs made them prone to recall bias, according to Ratti.

The study

The new study analyzed 41,428 MS-free participants from the Swedish National March Cohort, who completed detailed lifestyle and medical questionnaires.

Sweden has one of the world’s highest MS prevalence rates, at 215 per 100,000. Nearly one-third of participants (32.1 percent) were 45 or younger, and 61 percent reported being nonsmokers.

Researchers measured dietary intake using a validated 85-item Food Frequency Questionnaire, with participants reporting their average consumption of each food and beverage over the past year.

Adherence to the Mediterranean diet was measured using the 0-9 Mediterranean Diet Score, awarding points for above-average intake of healthy foods (vegetables, fruits, nuts, legumes, grains, fish, and favorable fat ratios) and below-average intake of unhealthy foods (meat and dairy). Participants were grouped into low (0-3), medium (4-5), and high (6-9) adherence, with analyses adjusted for sex, smoking, BMI, education, physical activity, energy intake, and vitamin D and B12 levels.

Findings of the study

Over 17.6 years, 89 participants developed MS, with each 1-point increase in the Mediterranean Diet Score linked to a 14 percent lower risk. Comparing adherence levels, medium adherence showed no risk reduction versus low, and although high adherence had lower risk, the difference was not statistically significant.

Smoking and age influenced the link between Mediterranean diet adherence and MS risk. Among nonsmokers, each 1-point increase in the diet score reduced risk by 26 percent, while no significant effect was seen in smokers, likely due to tobacco’s proinflammatory impact. Higher adherence also lowered risk in participants 45 or younger, but no significant benefit was observed in older individuals.

Limitations

With only 89 MS cases and diet assessed solely at baseline, the study’s statistical power is limited and may not generalize to younger at-risk populations.

Diet was recorded only once at baseline via self-report, and with a mean participant age of 52, the cohort was older than the typical MS at-risk population.