Compound in Carrots, Peppers Increases Brain Health

CHAMPAIGN, Ill.Individuals who eat more foods containing the plant compound luteolin may reduce the risk of age-related inflammation in the brain and related memory deficits, according to new study published in the Journal of Nutrition that found luteolin inhibits the release of inflammatory molecules in the brain.

Luteolin is found in many plants, including carrots, peppers, celery, olive oil, peppermint, rosemary and chamomile.

Researchers at the University of Illinois examined the effects of dietary luteolin in a mouse model of aging. They focused on microglial cells, specialized immune cells that reside in the brain and spinal cord. Infections stimulate microglia to produce signaling molecules, called cytokines, which spur a cascade of chemical changes in the brain. Inflammatory cytokines induce sleepiness, loss of appetite, memory deficits and depressive behaviors that often accompany illness.

Inflammation in the brain also may be a key contributor to age-related memory problems, said University of Illinois animal sciences professor Rodney Johnson, lead author of the study. We found previously that during normal aging, microglial cells become dysregulated and begin producing excessive levels of inflammatory cytokines," he said. We think this contributes to cognitive aging and is a predisposing factor for the development of neurodegenerative diseases."

The researchers showed that microglial cells that were exposed to a bacterial toxin produced inflammatory cytokines that could kill neurons. When the microglia were exposed to luteolin before they encountered the toxin, however, the neurons lived. Exposing only the neurons to luteolin before the experiment had no effect on their survival.

The researchers next turned their attention to the effects of luteolin on the brains and behavior of adult (3- to 6-month-old) and aged (2-year-old) mice. The mice were fed a control diet or a luteolin-supplemented diet for four weeks. They assessed their spatial memory and measured levels of inflammatory markers in the hippocampus, a brain region that is important to memory and spatial awareness.

Aged mice normally have higher levels of inflammatory molecules in the hippocampus and are more impaired on memory tests than younger adult mice. Aged mice on the luteolin-supplemented diet, however, did better on the learning and memory task than their peers, and the levels of inflammatory cytokines in their brains were more like those of the younger adult mice.

When we provided the old mice luteolin in the diet it reduced inflammation in the brain and at the same time restored working memory to what was seen in young cohorts," Johnson said. These data suggest that consuming a healthy diet has the potential to reduce age-associated inflammation in the brain, which can result in better cognitive health."