Zinc supplementation improved mental performance of 7th-grade boys and girls

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Colleagues, the following is FYI and does not necessarily reflect my own

opinion. I have no further knowledge of the topic.

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Public release date: 4-Apr-2005

http://www.eurekalert.org/pub_releases/2005-04/foas-zsi032005.php

Contact: Goodwin

ebpress@...

Federation of American Societies for Experimental Biology

Zinc supplementation improved mental performance of 7th-grade boys and girls

Seventh graders given 20 mg zinc, five days per week, for 10 to 12 weeks

showed improvement in mental performance, responding more quickly and

accurately on memory tasks and with more sustained attention, than

classmates who received no additional zinc. Beneficial effects were seen

regardless of the youngsters' previous zinc status. Dr. G.

Penland, Grand Forks Human Nutrition Research Center in North Dakota,

Agricultural Research Service, U.S. Department of Agriculture, presented

the findings at Experimental Biology 2005, as part of the scientific

sessions of the American Society of Nutritional Sciences. Although zinc

nutrition has been related to motor, cognitive and psychosocial function

in very young children and adults, this is the first study of its effect

in adolescents. Zinc deficiency is not uncommon, even in nations such as

the United States, and the risk is particularly high in adolescents,

says Dr. Penland, because they are undergoing rapid growth and often

have poor eating habits.

In the study, 209 seventh graders, 111 girls and 98 boys, consumed four

ounces of fruit juice containing either 0, 10 or 20 mg of zinc gluconate

each school day for 10 to 12 weeks. Students, their parents and teachers

did not know who was receiving which, if any, zinc supplementation until

the study was completed. At the beginning and end of the study, students

performed a battery of tasks designed to measure mental and motor

skills, like attention, memory, problem-solving and hand-eye coordination.

Examples include tapping a key on the keyboard as fast as possible,

using a mouse to follow an object moving across the screen, searching a

group of objects for two of a kind, learning and remembering lists of

words or simple geometric patterns, and categorizing objects. Students,

their parents, and teachers filled out questionnaires about the

students' mental, physical and social abilities and skills, school

performance, and problems in any of these areas to provide a measure of

psychosocial function. Blood samples measured zinc status before and

after the treatment.

Compared to the students who received no additional zinc, students who

consumed an additional 20 mg zinc each day decreased reaction time on a

visual memory task by 12 percent versus six percent; increased correct

answers on a word recognition task by 9 percent versus three percent;

and increased scores on a task requiring sustained attention and

vigilance by 6 percent versus one percent. Those who received only 10 mg

a day, the current Recommended Dietary Allowances (RDA) for this age

group, did not significantly improve performance, however.

Supplementation at either the 10 mg or 20 mg did not appear to improve

motor and social skills, although girls receiving the placebo

experienced a 10 percent increase in conduct problems during the study

while the behavior of girls receiving any level of zinc supplementation

remained unchanged. If further studies confirm that the mental function,

and in particular memory, of adolescents benefit from increasing zinc

intakes, says Dr. Penland, then this and other similar studies would

provide information that could be used when revising dietary guidelines

for zinc in this age group.

Such guidelines ultimately affect school breakfast and lunch menus, the

food guidance system, nutrition labels on food packages, and other uses.

Zinc is a common essential mineral found in foods, particularly red

meats, fish and grains. Previous studies have shown that zinc is needed

for growth and immune function and may be important for eye-hand

coordination and reasoning in very young children and in memory, muscle

strength and endurance in adults.

Dr. Penland's co-investigators are Dr. Henry C. Lukaski, also from the

Grand Forks Human Nutrition Research Center (GFHNRC), and Dr.

S. Gray, previously with GFHNRC and now with the Center for Rural Health

at the University of North Dakota.

--

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