Cognitive Psychology and Education

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Food Supplements and Cognition

Advertisers offer a range of food supplements that supposedly will make you smarter, improve your memory, help you think more clearly, and so on. Unfortunately, though, these supplements have usually not been tested in any systematic way. (In the United States and in many other countries, new medicines are tested before they are put on the market, but new food supplements are not.) In most cases, then, the claims made about these supplements are unsupported by evidence.

One supplement, though, has been widely endorsed and rigorously tested; this supplement is Ginkgo biloba , an extract derived from a tree of the same name and advertised as capable of enhancing memory. Is Ginkgo biloba effective? The answer begins with the fact that, for its normal functioning, the brain requires an excellent blood flow and, with that, a lot of oxygen and a lot of nutrients. Indeed, it is sometimes estimated that the brain, constituting just 2% of our body weight, consumes 15% percent of our body’s energy supply!

It’s not surprising, therefore, that the brain’s operations are impaired if some change in your health interferes with the flow of oxygen or nutrients. If (for example) you’re ill, or not eating enough, or not getting enough sleep, these conditions will affect virtually all aspects of your biological functioning. However, since the brain is so demanding of nutrients and oxygen, it’s one of the first organs to suffer if the supply of these necessities is compromised. This is why poor nutrition, or poor health, almost inevitably undermine your ability to think, to remember, to pay attention, and more.

Of course, the opposite is also true: A healthy diet, adequate exercise, and regular sleeping hours will improve the performance of all your bodily systems; but again, since the brain is so expensive to maintain, these different aspects of a healthy lifestyle are especially important for making sure your brain has the resources it needs to function well. The implications of this for students are clear.

But what about Ginkgo biloba? Evidence suggests that Ginkgo extract may improve blood circulation, reduce some sorts of bodily inflammation, and protect the nervous system from several types of damage. This is why researchers are examining this extract as a possible treatment for people who have troubles with blood circulation or who are at risk for nerve damage. In fact, results suggest that patients with Huntingdon’s disease, Alzheimer’s disease, and several other conditions may be helped by this food supplement—and, in particular, helped to remember more, and to think more clearly. Let’s be clear, though, that Ginkgo is not making these patients “smarter” in any direct fashion. Instead, the Ginkgo is broadly improving the patients’ blood circulation and the health status of their nerve cells, allowing these cells to do their work.

What about healthy people—people who are not suffering from bodily inflammations or damage to their brain cells? Will Ginkgo help them? Here the evidence is mixed. Some reviews offer the tentative conclusion that Ginkgo may improve the cognitive functioning of healthy young adults, but many studies have failed to observe any benefit from this food supplement, suggesting that Ginkgo’s effects, if they exist at all in healthy adults, are so small that they are difficult to detect.

Are there other steps that are more promising—steps that will improve the mental functioning of healthy young adults? We’ve already indicated part of a positive answer: Overall, good nutrition, plenty of sleep, adequate exercise, and so on will keep your blood supply in good condition, and this will help your brain to do its job. In addition, there may be something else you can do: The brain’s functioning depends on an adequate fuel supply, and that fuel supply comes from the sugar glucose. Crucially, the body’s neurons have no way to store glucose, and so, for their moment-by-moment functioning, they depend on the bloodstream to deliver a steady supply of this fuel.

You can protect yourself, therefore, by making sure that your brain has all the glucose it needs. This is not a recommendation to jettison all other aspects of your diet and eat nothing but chocolate bars. In fact, most of the glucose your body needs doesn’t come from sugary foods; most comes from the breakdown of carbohydrates, and so you get it from the grains, dairy products, fruits, and vegetables you eat. Thus, it might be a good idea to have a slice of bread and a glass of milk just before you take an exam, or just before you walk into a particularly challenging class. These steps will help ensure that you’re not caught by a glucose shortfall that could interfere with your brain’s functioning.

We need to be cautious, though, in how we think about these points. As one concern, you don’t want to gulp down too much sugar. If you do gobble up a candy bar just before your exam, or gulp down a large glass of sugary lemonade, you might produce an upward spike in your blood glucose followed by a sudden drop, and this can produce problems of its own. In addition, we should emphasize that the benefits of ingesting carbohydrates—even if you get the “dose” right—may be relatively small. This is because the glucose supply for the brain is tightly controlled by a number of different mechanisms inside the body, and these mechanisms usually guarantee that your brain gets the sugar it needs. As a result, the extra glucose you might obtain from a fast snack may just get “set aside” by the liver and not be sent to the brain at all.

In short, then, the evidence suggests that food supplements offer no “fast track” toward better cognition. Ginkgo is helpful, but mostly for special populations. A high-carb snack may help, but will be of little value if you’re already adequately nourished. Thus, on all these grounds, the best path toward better cognition seems, in some ways, to be the one that common sense would already recommend—a balanced diet, a good night’s sleep, and paying careful attention during your studies.

Critical Questions

1.
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Why might the effects of Ginkgo biloba on cognitive functioning be rather indirect?
2.
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What are some changes that you can make to your day-to-day lifestyle to improve the functioning of your brain?
3. Although our brains depend heavily on glucose for energy, we do not have to eat sugary foods to maintain healthy levels of glucose in the blood. Spend a few minutes researching the dietary sources of glucose.

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