Foods may affect the brain as well as the body

[Lolly]

http://sciencenews.org/articles/20060304/bob8.asp
Foods may affect the brain as well as the body
Christen Brownlee

This is part two of a two-part series on lifestyle and brain fitness. Part I: "Buff and Brainy," is available at http://www.sciencenews.org/articles/20060225/bob10.asp.

At family dinner tables around the globe, prodding mothers have dished out the same refrain for decades: "Eat your fish," they say. "It's brain food!" For children picking at crusty fish sticks or blobs of pink poached salmon, the statement raises suspicions. But the message is turning out to be more than just an attempt to get children to clean their plates. Recent research is suggesting that what you eat can influence the function of your brain.

Scientists are providing hints that what you choose to consume or avoid in your daily diet can have consequences on the brain's resiliency in the face of injury or disease. Studies suggest that foods such as fish and a curry spice called curcumin, for example, can give the brain an added edge to stay healthy...

...Taken together, these results point in a direction that any kid could have seen coming: Once again, Mom was right.

Fish curry

Besides a mother's goading, there are plenty of reasons to eat a succulent fillet of fish. The strongest incentive, neuroscientists say, may lie in the growing number of benefits attributed to nutrients known as omega-3 fatty acids, found in small amounts in some plants and in abundance in oily, cold-water fish such as salmon.

Neurosurgery professor Fernando Gómez-Pinilla operates a traumatic brain-injury center at the University of California, Los Angeles (UCLA). Because his past studies suggested that exercise affects how well brains function (SN: 2/25/06, p. 122: http://www.sciencenews.org/articles/20060225/bob10.asp), he wondered whether diet might also change how his patients coped with brain injuries.

Working with rats, Gómez-Pinilla and his colleagues compared the effects of two diets. Both included healthy, low-fat chow. However, one diet contained 8 percent fish oil—the amount people would receive by eating fish about twice a week. After 4 weeks, Gómez-Pinilla's team subjected some of the rats to a mild percussion injury—a knock on the head in a machine specially designed to standardize the force of its blows.

The researchers tested all the animals a week later in a water maze to see how quickly the rats could learn the location of a platform hidden beneath the water's milky surface. They found that brain-injured rats fed the fish oil-supplemented diet found the platform's location in about two-thirds of the time it took the injured rats that ate the standard rat chow to do so. Surprisingly, Gómez-Pinilla says, the injured rats fed the fish oil mastered the maze almost as quickly as rats that weren't injured did.

He and his colleagues found that rats that had eaten unsupplemented chow had lower brain concentrations of a protein called brain-derived neurotrophic factor (BDNF). This compound encourages nerve cells to grow and make new connections. BDNF concentrations are typically low after the type of injury that the rats had experienced. In contrast, BDNF concentrations in rats fed fish oil were much like those in rodents that hadn't received brain injuries.

Gómez-Pinilla and other scientists have shown in previous studies that nerve cells produce BDNF when animals exercise. This protein may be a prime player in the neurological benefits that animals get from exercise.

Researchers aren't yet sure how the components of fish oil change BDNF amounts in the brain. However, Gómez-Pinilla says, "eating a diet rich in omega-3 fatty acids could have some of the same [neurological] effects as exercise."...

...Neuroscientist Greg M. Cole, working in another laboratory at UCLA and also at the Veterans Administration Medical Center in Sepulveda, Calif. is finding that supplementing food with just the omega-3 fatty acid DHA—rather than the complex blend of fish-oil ingredients—can dramatically slow neurodegenerative symptoms in mice bred to develop an Alzheimer's-like disease...



Fat attack

"...Just as fish oil and curcumin seem to aid the brain, other foods—such as those in the typical high-fat, sugary U.S. diet—could take brain health down a notch.

Four years ago, Gómez-Pinilla and his colleagues tested how the typical diet of people in industrialized Western countries affected brain function in rats. The researchers fed half of a group of rats a regular lab diet composed of about 13 percent fat and 59 percent complex carbohydrates, among other nutrients. The other animals received a high-fat and high-sugar (HFS) diet made with 39 percent fat, primarily from lard and corn oil, and 40 percent refined white sugar.

After just 2 months, Gómez-Pinilla's team found that animals on the standard diet learned the water-maze task faster than did rats on the HFS diet. When the scientists dissected the animals' brains after a year on the special diets, they found that rats on the HFS diet had less than half as much BDNF as mice on the healthy diet did. The HFS rats also had reduced amounts of several other proteins associated with learning and memory.

In another experiment published 2 years later, Gómez-Pinilla tested how rats on the two diets fared after a mild brain injury such as the one that the rats on the fish oil diets had been subjected to. Animals ate their assigned diet for 4 weeks then received a mild brain injury. In the water maze, both sets of animals had performed equally well before being injured. However, rats fed the HFS diet showed greater deficits in learning the maze a week after their percussion injuries than did rats fed the regular diet.

When the scientists examined the animals' brains, they found that rats on the HFS diet had lower amounts of BDNF than those on the healthy diet did. A shortage of BDNF could underlie the animals' inability to recover from their neurological injuries as well as the other rats did, says Gómez-Pinilla..."