In a 10-week study of 209 seventh graders, those who
consumed fruit juice supplemented with zinc cut their reaction
time on a visual memory test by 12 percent compared with 6
percent for students who received regular juice.
They also had more correct answers on a word recognition
test and had better scores on a task requiring sustained
attention and vigilance.
However, test performance did not improve significantly in
students who were already meeting recommended daily allowances
for zinc intake.
If confirmed, these results may help fuel a review of
recommended zinc intake guidelines for adolescents, Dr. James
G. Penland from the Grand Forks Human Nutrition Research Center
in North Dakota noted in a telephone interview with Reuters
Health.
It's important to remember that these results were achieved
in a group of adolescents who were not zinc deficient, he
emphasized. "So if we could see benefits from slightly
increasing zinc intake in that group it bodes well for what we
might find with a zinc deficient population," he said.
"Adolescence is a critical period of rapid growth
physically, emotionally and mentally. That coupled with the
fact that zinc is one of the nutrients that adolescents do not
consume in recommended amounts led us to this study," Penland
added.
Supplemental zinc did not appear to improve motor or
psychosocial functioning in the current study, although conduct
problems increased by 10 percent in girls who were given juice
lacking zinc.
