By Lauren Aaronson, published on July 1, 2005 - last reviewed on June 8, 2012
When I was 7 years old, I read in the sequel to Little Women that oatmeal made you smart. So I demanded that my mother feed me oatmeal on the day of my spelling test. I ate oatmeal before every test I ever took from elementary school through grad school. I even made my mother mail me oatmeal when I had a big exam during my semester abroad; later I thanked both my mom and Quaker Oats: I got a perfect score.
My mother chalked up my success to superstition. But I still believe that the oatmeal itself made a difference. And now it looks like science will prove me and the book's heroine, Jo March, right.
Like just about anything we eat, oatmeal influences the way our brains function. Food, after all, gives our bodies the raw materials to build everything from noses to neurons and the ability to operate them efficiently. Some materials make for better outcomes than others, as a flood of studies attest.
Fibrous oatmeal, for instance, slowly and steadily ushered the cereal's cargo of carbohydrates into my system as glucose. My brain snapped up that sugar from the bloodstream and deployed it both as fuel to power its operations and as a component of key chemical messengers, the very neurotransmitters that carry thoughts and memories. Oatmeal revved up my brain and stabilized my mood, memory and concentration—all without the spiky highs or crashing lows of foods like candy bars that dump their payload of sugar quickly.
Unbeknownst to me, my morning oatmeal also supplied ferulic acid. A potent antioxidant lurking in the germ and bran of grains, ferulic acid appears to be a general protector of brain cells, keeping them supple and responsive by nullifying toxins that stiffen them with age—and possibly even reversing some of the cognitive decline of aging.
A bowlful of gruel is hardly the fashionable food of choice. But oatmeal sits, however lumpily, at the cutting edge of a revolution in the way we think about food. Nutritional science is demonstrating that some edibles—call them functional foods—do far more than provide essential nutrients for normal maintenance and development. They furnish biologically active components that create high-class physiologic effects, such as disarming toxins, and impart health benefits. They have the capacity to reduce disease risk—with minimal involvement of health professionals," the nation's food scientists say.
"Food has a greater impact on health than previously known," declares a report released by the Institute of Food Technologists. "New evidence-based science linking diet to disease and disease prevention" has "blurred the line between food and medicine." Nutrients influence body processes at the molecular level, turning our very genes on and off. The emerging understanding of molecular nutrition, says the IFT, "has the potential to revolutionize diet, nutrition and food products, and health care."
Scarcely a week goes by when scientists don't make some discovery about the health-enhancing properties of food, from the cancer-fighting abilities of brussels sprouts to the anti-Alzheimer's effects of anchovies. For the nation's nutritional scientists, that presents a significant problem: There's no longer a clear boundary between foods and drugs. In some cases—antioxidant-rich cranberry juice, for example—the health claims for nutrients actually have to be soft-pedaled, lest they trigger regulations that require foods to undergo the same approval process as drugs. The IFT is urging the Food and Drug Administration to adopt reasonable procedures for demonstrating safety and efficacy of foods that are, well, more than foods—what some people call "nutraceuticals."
Oatmeal in fact inspired one of the earliest druglike claims for a food. In 1997 the Quaker Oats box began touting the cholesterol-lowering effects of the cereal after the FDA evaluated studies linking whole grains to reductions in the blood fat.
Food-boosted health now goes way beyond the heart, all the way to the head. Of course, brain virtuosity also hinges on physical and mental activity, as well as on factors not yet understood. But there's no question that proper feeding primes our brains to reach their fullest potential and maintain their wits for a lifetime.
Everyday nutrients are involved in a dazzling array of sophisticated actions at the molecular level. Nevertheless, the latest research on functional foods highlights six strategic lines of defense on the route from mouth to mind. Some functional food superstars make use of more than one mechanism.
The Telltale Heart: Jogging the Mind
Food doesn't have to reach your head to improve your memory. "There's getting to be a general consensus that what is good for your heart is good for your brain," says James Joseph, a neuroscientist at the Human Nutrition Research Center at Tufts University in Massachusetts.
Your brain accounts for just 2 percent of your body weight, but it eats up about 20 percent of your oxygen intake. Since it's such a hungry organ, your brain depends on a strong cardiovascular system to ferry in supplies. Healthy blood pressure and cholesterol levels keep your arteries clear, leaving them free to transport nutrients to your brain. Clear arteries also reduce risk of stroke, which kills neurons when a blocked or ruptured vessel cuts off blood flow.
Any steps you take to improve the delivery of oxygen to your heart—that two-mile jog, for example—automatically pump up your brain. The steps include well-known dietary cardiovascular strengtheners like fiber-rich foods, which lower cholesterol; leafy greens rich in B vitamins and folate, which reduce levels of vessel-harming homocysteine; omega-3 fatty acids, which may prevent arrhythmias; and exercise, which reduces blood pressure, helps control blood-fat levels and keeps weight in check.
Brain-boosting steps may also include downright counterintuitive measures. Women who have one alcoholic drink a day—be it wine, beer or that cosmopolitan—have a much lower risk of cognitive decline than either teetotalers or heavy drinkers, according to a study at the Harvard School of Public Health. It's the effect of alcohol on your blood. By elevating levels of "good" cholesterol, thereby lowering the risk of stroke, small amounts of alcohol may protect both your cardiovascular system and the brain it serves.
Your brain is the only organ that draws nearly all its energy from glucose, the sugar in ripe grapes and honey, for example, and produced in quantity from pasta and other starchy carbohydrates. That sweet substance also fuels the formation of sweet memories, or at least reliable ones.
Lab experiments reveal that a dose of glucose-sweetened lemonade boosts recall of events, words, movements, drawings and faces, among other things, with effects lasting long enough to get you through a two-hour exam. Other research extends these findings from doctored drinks to regular food. Any carbohydrate-rich dish, such as a bagel or a thick slice of bread, may prompt similar memory enhancements for healthy adults.
While a candy bar provides a burst of brain energy, that flash quickly subsides and your blood-sugar level plummets, fueling the desire for another ride on the blood-sugar roller coaster. Both body and brain may do better with foods that score low on the glycemic index, a rating that measures how fast and how high a food increases blood glucose levels after it's consumed. Because they surrender their starches slowly, such fiber-rich foods as barley, beans and Jo March's oatmeal all provide a steadier—and less fattening—stream of energy than a Snickers bar.
Over the long term, less-fattening foods benefit body, blood and brain. A healthy weight helps prevent diabetes and impaired glucose tolerance, conditions associated with a decline in cognitive capacity. Compared to glucose-intolerant adults, people with a well-maintained energy supply hang on longer to their memories.
Signal Savers: Salmon Tales
Neurons, the main cells in your brain, are a bit like New York City: bustling with activity but walled off from the outside by rivers and membranes, respectively. For neurons to survive and contribute to the world, their walls need to let vital goods pass in and out.
A healthy cell in its prime has a supple membrane that allows important molecules to cross unimpeded, as if over the Brooklyn Bridge at midnight. As a cell ages, though, the materials in the membrane stiffen and make it less pliable. With bridges and tunnels closing down, tollbooth like receptors on the surface of the membrane don't collect as many incoming signals from message-carrying neurotransmitters as they should. You might feel such effects as sluggishness in learning the new and recalling the old, poor sleep, lowered pain threshold. Impaired body-temperature regulation could make you uncomfortable in ordinary settings.
The neuronal membrane is made up primarily of fats, the very same fats that you fork into your mouth. In fact, your brain has your body's second-highest concentration of fat, right after actual fatty tissue—think butt and belly—itself.
The kinds of fats in the foods you eat influence the character of your cell membranes. Cholesterol and saturated fats harden membranes, while essential polyunsaturated fatty acids—omega-3s and omega-6s—render them supple. A healthy mix of essential fatty acids seems to enhance learning by facilitating the smooth passage of signals through neuronal membranes.
Most Americans take in plenty of omega-6 fatty acids, via nearly ubiquitous soy and corn oils. But the typical American diet lacks sufficient omega-3s, notes David I. Mostofsky, a neuroscientist at Boston University. Within days after you add omega-3s to your diet, membranes are rejuvenated in composition.
Salmon and other coldwater fish and (perhaps less appetizingly) algae are rich sources of the omega-3 fats that your body can utilize directly from food—known as EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). Walnuts and flaxseeds are rich in a related substance, alpha-linolenic acid, which can be converted more or less efficiently to EPA and DHA in the body. Human breast milk is rich in all three fatty acids, and DHA provides critical insulation for an infant's developing nervous system.
Under the direction of Gregory Cole, the Alzheimer's Disease Research Center at the University of California at Los Angeles is preparing to test whether omega-3 fatty acids can deter Alzheimer's disease, the number one cause of cognitive decline. So far, the fats have successfully fended off dementia in lab rats.
Tests of omega-3s are underway for a variety of other conditions, ranging from sleep disorders and anxiety to depression and impaired immune responses. "Nobody fully understands why they should have so many different functions," muses Mostofsky. Perhaps it's because the neuronal membrane controls access to all other nerve-cell functions.
Once nutrients make their way into a neuron, small furnaces within the cells turn them into energy by combusting glucose and oxygen. The cellular furnaces, known as mitochondria, create energy less efficiently as you age. As mitochondria sputter, cells have less energy to power critical activities like the repair of everyday damage and replication of DNA. The downslide in cell metabolism likely contributes to the cognitive decline seen with age.
What's more, mitochondria spew cell-damaging free radicals of oxygen into their environment, and the more they age, the more renegade free radicals they generate. "It's like an old car engine that's spitting out black smoke," explains Bruce Ames, professor of biochemistry and molecular biology at the University of California at Berkeley.
Give mitochondria a tune-up, reasons Ames, and they'll turn out more energy and fewer free radicals. He focuses on two food-based mitochondrial boosters: acetyl-L-carnitine and lipoic acid. Acetyl-L-carnitine, a version of an amino acid found in meat, milk and avocado, helps shuttle fatty acids into mitochondria. Lipoic acid, found in beef, spinach and broccoli, quenches free radicals. In cahoots, these compounds in high concentrations combat memory loss in lab rats, Ames reports. He's testing a combination pill for people.
Another dietary factor—or, more precisely, lack thereof—may beef up mitochondrial function. Low caloric intake, shown to prolong the life span of rats, also seems to revive mitochondrial function, perhaps because mitochondria with fewer nutrients to burn emit fewer free radicals.
It may also do more—promote the growth of entirely new neurons. Mark P. Mattson, chief of the neurosciences lab at the National Institute on Aging and flag bearer for low-cal research, advises people who are overweight to cut back on calories. The benefits are less clear for people who are already of normal weight.
Along with an increase in free radicals, aging can bring a decrease in the body's ability to deal with these errant molecules, which have a particular affinity for attacking cell membranes. And in a vicious cycle, the damage caused by unchecked free radicals—a.k.a., oxidative stress—ends up compounding the aging process.
"Every major disease that kills people in this country has an oxidative stress component," says Joseph of Tufts University. For him and other researchers interested in preserving the brain's ability to function, oxidative stress seems like a natural enemy. The scientists also have natural allies: fruits and vegetables. They contain a whole circus troupe of antioxidants, colorful substances that arrest free radicals by nullifying their rogue electrons.
Some antioxidants are already familiar faces in nutrition. Vitamins C and E, for instance, are the main antioxidants in the brain. But they're getting new respect as potential keepers of brain health, since they appear to guard aging neuronal membranes from free radicals.
Other antioxidants have stepped into the limelight. Many are natural chemicals that plants have evolved to protect themselves from disease. The major antioxidants in plants, known as flavonoids, come in two main flavors: anthocyanins, in brightly colored fruits, and their colorless cousins, anthoxanthins, found notably in green tea (epigallocatechins) and soybeans (isoflavones).
With a rich load of anthocyanins, the most colorful produce also tends to be the most potent. Blueberries, blackberries and cranberries offer more antioxidant protection than the legendarily nutritious brussels sprout. Their antioxidants also have anti-inflammatory actions, soothing overagitated immune cells that may hamper brain activity.
In practice, the petite blueberry reverses some of the effects of aging on the brain, boosting short-term memory and spatial learning—reviving the ability of doddery lab rats to move through mazes. People who eat a cup of blueberries a day perform well on tests of motor skills. Purple grape juice, similarly rich in flavonoids, similarly boosts performance. Grape juice and red wine also promise to stave off heart disease, in part because of the activity of another powerful antioxidant, resveratrol.
The garishly yellow spice turmeric excites researchers beyond its vibrancy of color. Its active component, curcumin, has both antioxidant and anti-inflammatory properties; further, it may act as an iron chelator, removing harmful buildup of metal associated with neurodegenerative diseases. Lab tests suggest that it directly targets the brain plaques linked to Alzheimer's disease. "It's binding to the supposedly toxic stuff," and disarms it, explains Greg Cole of UCLA.
Adding to the excitement surrounding the flashy turmeric seed, Cole is evaluating the effectiveness of curcumin as an Alzheimer's treatment. His trials may help explain why India, where turmeric commonly tints curry dishes, has a particularly low rate of Alzheimer's.
Whether hot curry dishes or cool glasses of juice, whole foods may hold on to nutrient benefits that concentrated supplements cannot. "There is some evidence that the vitamins from food are more efficient," says D. Allan Butterfield, a biochemist at the Sanders-Brown Center on Aging at the University of Kentucky.
Signs of Success: Eggheads
Research in nutrition zeroes in on the classiest work of the brain: learning and remembering.
Nutrients provide the building blocks of neurotransmitters, the chemicals that carry messages between brain cells—messages like "Grow" or "Pssst, pass this on." Both glucose and vitamin B1, for instance, feed production of acetylcholine, a neurotransmitter that appears to play a large role in memory formation. Adequate amounts of B1, as well as the other B vitamins, are necessary for everyday brain health.
Still, upping levels of nutrients may boost specific neurotransmitters in your brain, abetting the cell-to-cell signaling that delivers, say, a memory to mind. "If I give you more choline [a fatlike essential nutrient related to the B vitamins, found in eggs, liver and soybeans], your brain cells will immediately make more acetylcholine," says Richard Wurtman, professor of neuropharmacology and director of the Clinical Research Center at Massachusetts Institute of Technology. In lab rats a surge in acetylcholine leads to memory improvements a month later. Normal human brain function requires adequate intake of choline, but it's not clear whether extra choline brings extra cognitive benefits—although, interestingly, Alzheimer's patients show drastically reduced acetylcholine levels.
Some familiar antioxidants may also boost learning by abetting the signaling that takes place inside brain cells and modulating the expression of genes, influencing the survival and growth of nerve cells. Blueberries appear to help rat brains from within, in ways that even surpass their antioxidant activity, says scientist Joseph of Tufts University.
Green tea may similarly protect neurons through related signaling mechanisms. Both edibles are still under investigation, since cell signaling ranks among the newest frontiers at the intersection between nutrition and neuroscience.
As hot as the frontier now is, it turns out that the idea that food may be our brain's best medicine isn't novel at all. Jo March, the oatmeal muse who altered my eating habits for life, got there well before the scientists. "Don't worry, my dear," she says in Jo's Boys. "That active brain of yours was starving for good food; it has plenty now."