Antioxidant-Rich Diets Reduce Brain Damage from Stroke in Rats

Newswise — Your mother was right. Eat your fruits and veggies -- they're good for you!

And if that's not reason enough, a new study suggests antioxidant-rich fruits and vegetables may limit brain damage from stroke and other neurological disorders. The study, conducted by researchers at the University of South Florida College of Medicine, James A. Haley Veterans' Hospital and the National Institute on Drug Abuse, is posted online and will be published in the May issue of the journal Experimental Neurology.

USF/VA neuroscientist Paula Bickford, PhD, and colleagues found that rats fed diets preventatively enriched with blueberries, spinach or an algae known as spirulina experienced less brain cell loss and improved recovery of movement following a stroke.

The study builds upon previous USF/VA research showing that diets enriched with blueberries, spinach or spirulina reversed normal age-related declines in memory and learning in old rats.

"I was amazed at the extent of neuroprotection these antioxidant-rich diets provided," said Dr. Bickford, a researcher at the USF Center for Aging and Brain Repair and James A. Haley Veterans' Hospital. "The size of the stroke was 50 to 75 percent less in rats treated with diets supplemented with blueberries, spinach or spirulina before the stroke."

Antioxidant and anti-inflammatory substances in these fruits and vegetables may somehow reduce the nerve cell injury and death triggered by a stroke, the researchers suggest. "The clinical implication is that increasing fruit and vegetable consumption may make a difference in the severity of a stroke," Dr. Bickford said. "It could be a readily available, inexpensive and relatively safe way to benefit stroke patients."

The researchers studied four groups of rats, all fed equal amounts of food for one month. One group was fed rat chow supplemented with blueberries, a second group chow with spinach, and the third chow with spirulina. The control (untreated) group ate chow only.

After four weeks, an ischemic stroke with reperfusion was induced in the rats. An ischemic stroke occurs when a blood clot cuts off the oxygen supply to the brain like the kink in a hose cuts off water flow. Then, later, the clot is released and blood flow returns, which is known as reperfusion.

The size of the stroke in the rats fed blueberry or spinach supplements was half that seen in the brains of untreated rats. Rats fed spirulina-enriched diets had stroke lesions 75 percent smaller than their untreated counterparts. In addition, rats pretreated with the blueberry, spinach or spirulina diets showed greater increases in poststroke movement than the control group.

All the supplemented diets were rich in antioxidants, which scientists say may counteract the burst of free radicals involved in the cascade of brain cell death triggered by an ischemic stroke. An excess of free radicals can damage cellular lipids, proteins and DNA.

The supplemented diets also contained anti-inflammatory substances that may help reduce inflammation-induced injury following a stroke, Dr. Bickford said. When a stroke occurs, immune cells in the brain mount an inflammatory response " rushing to the site of injury to clear away the dead and dying cells. As a result, nearby healthy nerve cells may suffer collateral damage much the same way firefighters breaking into an apartment to put out a fire in one room may inadvertently cause damage to other rooms.

Teasing out just which beneficial chemicals contained in the blueberries and leafy greens might be reproduced therapeutically in pill form is difficult, Dr. Bickford said. "Whole foods contain multiple nutrients, so there are many different ways these diets could be protecting the brain. From a scientific perspective, it's a package deal."

Dr. Bickford's team is investigating whether rats treated with antioxidant-rich diets following strokes will experience improved recovery. The researchers also plan to study whether combinations of the diets might provide even greater protection against stroke damage than one diet alone.

The study was supported by grants from the National Institute on Drug Abuse and the Veterans Administration.