Mediterranean Diet Lowers White Matter Hyperintensity Volume

By Allison Shelley | medscape.com | February 15, 2012

A diet rich in vegetables, legumes, fruits, and olive oil and low in dairy, red meat, and processed meat appears to lower white matter hyperintensity volume, new work from the Northern Manhattan Study shows.

“A Mediterranean-style diet may be protective against small vessel disease in the brain,” senior investigator Clinton Wright, MD, from the University of Miami in Florida, told Medscape Medical News. “This is important because it suggests that a Mediterranean-style diet could lower the risk of vascular disease affecting the brain once confirmed in prospective studies.”

The cross-sectional analysis of a longitudinal population-based cohort is published in the February issue of the Archives of Neurology.

The team, led by Hannah Gardener, ScD, who is also from the University of Miami, studied 966 people who responded to a semiquantitative food frequency questionnaire. A score of 0 to 9 was calculated to reflect an increasing similarity to the Mediterranean diet pattern.

Using quantitative brain magnetic resonance imaging, the researchers measured white matter hyperintensity volume.

Investigators then constructed linear regression models to examine the association between the Mediterranean diet score and the log-transformed white matter hyperintensity volume as a proportion of total cranial volume, controlling for sociodemographic and vascular risk factors.

They found that each 1-point increase in Mediterranean diet score was associated with a lower log white matter hyperintensity volume (β = -.04, = .01).

Women had lower Mediterranean diet scores than men. Participants who reported moderate to heavy levels of physical activity were also more likely to report eating a healthy diet. People with Mediterranean diet scores of 6 or higher also had lower body mass index.

Distribution of Mediterranean Diet Scale Scores
ScorePercentage
0 – 211.6
315.8
423.0
523.5
6 – 926.1

The association was independent of sociodemographic and vascular risk factors, including physical activity, smoking, blood lipid levels, hypertension, diabetes, a history of cardiac disease, and body mass index.

The only component of the Mediterranean diet score that was an independent predictor of white matter hyperintensity volume was the ratio of monounsaturated fat to saturated fat (β = -.20, = .001).

“We were not surprised, because a body of evidence exists showing a lower risk of cardiovascular outcomes and mortality among those adhering to a Mediterranean-style diet,” Dr. Wright said. “We confirmed our hypothesis that this type of diet might be associated with less subclinical damage as well.”

The authors acknowledge the limits of their cross-sectional, observational study and point out that more work remains to establish a causal relationship between the Mediterranean-style diet and white matter disease.

Protective Effect

There is mounting evidence suggesting that diet can have a protective or destructive effect on the brain. In a study published in the June issue of the Archives of Neurology and reported by Medscape Medical News at the time, investigators showed that healthy, cognitively intact older adults who stuck to a low-saturated-fat, low-glycemic-index diet experienced decreases in levels of β-amyloid 42 in cerebrospinal fluid. β-Amyloid 42 is a biomarker associated with an increased risk for Alzheimer’s disease.

In healthy adults, the high-fat diet increased β-amyloid levels, increased concentrations of the oxidative stress marker F2-isoprostane, and lowered insulin levels.

The authors conclude that a diet like the Mediterranean-style diet seems to have a protective effect, and consuming a lot of saturated fat and sugar appears to place patients at greater risk.

This study is funded by the National Institute of Neurological Disorders and Stroke, the American Heart Association, and the McKnight Brain Research Institute. The investigators have disclosed no relevant financial relationships.

Arch Neurol. 2012;69:251-256. Abstract