& Joannie Dobbs Monday,
Exam cram requires good food, rest
With the end of the school year close, high school and college students are concerned about finishing up term papers and taking final exams. Of course, there is no substitute for putting in the time required for work and study. But there is scientific evidence that food and sleep habits can affect mental function.
Question: How can nutrients enhance brain function?
Answer: The brain requires a constant source of energy and burns a lot of calories for its size. Although it is only about 2 percent of total body weight, when the body is at rest, the brain uses about 20 percent of the total calories being expended by the whole body.
The brain likes sugar. Almost all the energy used by the brain comes from glucose obtained from the blood. Consequently, many studies have tested whether glucose levels in the blood affect brain function.
Q: Can eating certain types of foods enhance brain function?
A: Based on research conducted on brain nutrition and mental performance, the most important food components for brain function are carbohydrate and protein. Ideally, the carbohydrate is one with a low glycemic index, meaning that it results in a more gradual rise and fall in blood glucose levels.
Pre-exam meals that meet these criteria include whole-grain cereal with milk and fruit, yogurt with fruit, miso soup with some rice, etc. The meal should not be too large. A heavy meal can cause tiredness because extra blood flows to the intestines to aid in digestion and absorption of nutrients.
Those following low-carb diets may do better on mental tasks if they slack off and let some carbs into their diet.
Q: How important is breakfast for brain function?
A: A number of studies have indicated that breakfast is, in fact, the most important meal of the day. Morning is when blood glucose is typically at its lowest. Even a light breakfast can give blood glucose, and thus brain function, a boost.
Q: Can snacks affect brain performance?
A: Unless a person is diabetic, blood glucose typically drops about two hours after a meal, depending on the size and carbohydrate content of the meal. A light snack such as fruit or yogurt might give blood glucose the slight rise needed to maintain optimal brain function.
Q : Can nutritional supplements affect brain function?
A: David Benton at the University of Wales-Swansea found in studies that some children experienced improved mental function when given multivitamin/mineral supplements. But it appears that only those with inadequate diets benefited.
Q: How important is sleep?
A: According to research by Gregory Belenky at Walter Reed Army Institute, "The ability to do useful mental work declines by 25 percent for every successive 24 hours awake." Uninterrupted sleep of seven hours or longer promotes the best mental performance. All-nighters can backfire!
Alan Titchenal, Ph.D., C.N.S. and Joannie Dobbs, Ph.D., C.N.S.
are nutritionists in the Department of Human Nutrition, Food and Animal Sciences,
College of Tropical Agriculture and Human Resources, UH-Manoa.
Dr. Dobbs also works with the University Health Service
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