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青山妩媚

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Smart Girls Eat Fish  

2008-06-22 09:37:52|  分类: 營養健康 |  标签: |举报 |字号 订阅

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    Smart Girls Eat Fish - 青山妩媚 - 青山妩媚Smart Girls Eat Fish - 青山妩媚 - 青山妩媚 Girls who eat more omega-3 fatty acids outsmart those who eat higher amounts of omega-6 fatty acids, according to new research. As a result of this and other studies, government dietary recommendations--especially those aimed at pregnant women--should emphasize fish over soy and corn oils, which are respectively high in these fatty acids, says Joseph Hibbeln, a psychiatrist and lipid biochemist at the National Institute on Alcohol Abuse and Alcoholism in Bethesda, Maryland. "We don't want the brain to be deficient in its critical nutrients during development."

The omega-3 advantage was first hinted at in studies of distribution of body fat. Earlier this year, William Lassek, an epidemiologist at the University of Pittsburgh in Pennsylvania, and anthropologist Steven Gaulin of the University of California, Santa Barbara, reported that women who accumulated more fat on their hips than on their waists--and who, therefore, had low waist-hip ratios like many movie stars--had higher cognitive test scores, as did their children. They proposed that because the fat on the hips and thighs contains more omega-3s than belly fat does, these women were storing omega-3s critical for fetal and infant brain development--and boosting their own brainpower as they grew up. They also predicted that women who ate more omega-3s would perform better on cognitive tests than those who ate more omega-6s.

To test this hypothesis, Lassek and Gaulin analyzed data on about 4000 girls and boys between the ages of 6 and 16. The children had participated in the Third National Health and Nutrition Examination Study, part of a U.S. project to assess the health and nutritional status of kids and adults. After the researchers controlled for the parents' income and education and for the children's age, race, number of siblings, and blood lead levels, they found that girls who ate more omega-3 scored significantly better on four cognitive tests, including an IQ test.

Although genetics and parental education influence intelligence far more, the dietary effect explained about 1% of the difference in test scores between girls, about the same amount as exposure to lead, says Lassek. Boys also perform a bit better on cognitive tests if they eat more omega-3s than other fatty acids, but the effect is "twice as great in girls as in boys," says Lassek. That disparity suggests that evolution has favored girls who stow omega-3 fats on their lower bodies. The team, which presented its findings earlier this month at the Human Behavior and Evolution Society meeting in Kyoto, Japan, also found that omega-6 fatty acids interfere with cognition, because girls who ate more of these oils didn't perform as well.

Other researchers who have studied omega-3s are not surprised to see the link between omega-3s and intelligence: "Deficiency in omega-3 intake in modern diets is associated with an increased risk of violence, major depression, suicide, and bipolar disorder," says Hibbeln, so seeing a connection to another aspect of brain function makes sense, particularly because neurons use fatty acids to build axons. Most important, he says, is the omega-6 finding. "The big change in the Western diet of the past 100 years is a massive increase in the dietary intake of omega-6 fatty acids," he says. Hibbeln has advised the U.S. government to revise its recent advisory warning that pregnant women reduce their consumption of fish during pregnancy because of mercury toxicity; he says the dangers can be avoided easily by limiting consumption of certain fish.

http://sciencenow.sciencemag.org/cgi/content/full/2008/620/3

Taking On the Thin Ideal:

There's nothing new about TV and fashion magazines giving girls unhealthy ideas about how thin they need to be in order to be considered beautiful. What is surprising is the method psychologists at the University of Texas have come up with to keep girls from developing eating disorders. Their main weapon against superskinny (role) models: a brand of civil disobedience dubbed "body activism." Related Articles

Since 2001, more than 1,000 high school and college students have participated in the Body Project, which works by getting girls to understand how they have been buying into the notion that you have to be thin to be happy or successful. After critiquing the so-called thin ideal by writing essays and role-playing with their peers, participants are directed to come up with and execute small, nonviolent acts. They include slipping notes saying "Love your body the way it is" into dieting books at stores like Borders and writing letters to Mattel, makers of the impossibly proportioned Barbie doll.

According to a study in the latest issue of the Journal of Consulting and Clinical Psychology, the risk of developing eating disorders was reduced 61% among Body Project participants. And they continued to exhibit positive body-image attitudes as long as three years after completing the program, which consists of four one-hour sessions. Such lasting effects may be due to girls' realizing not only how they were being influenced but also who was benefiting from the societal pressure to be thin. "These people who promote the perfect body really don't care about you at all," says Kelsey Hertel, a high school junior and Body Project veteran in Eugene, Ore. "They purposefully make you feel like less of a person so you'll buy their stuff and they'll make money."

As part of the program, Hertel and a friend posted signs in a school bathroom saying YOU ARE BEAUTIFUL. DON'T BE SOMEONE THAT YOU'RE NOT. BE YOURSELF. The girls then watched their classmates react. "They'd see the signs and say things like 'That's encouraging because I always feel so fat and gross and ugly,'" Hertel says. The study's lead author, Eric Stice, designed the Body Project betting that a crucial element in preventing eating disorders lay in getting a participant to critique a fashion ad or other negative influence in front of her peers. "If I write down 10 things bad about it and post it on MySpace so anyone can view it, I'm accountable for it," says Stice, now at the Oregon Research Institute.

Psychologists are excited about his study because there's not a lot of other data measuring the effectiveness of such programs, let alone their long-term impact.

"This is a good start," says Dr. Walter Kaye, a board member of the National Eating Disorders Association. But Kaye cautions that eating disorders are much more complicated than researchers first thought. For starters, the disorders can't be blamed solely on environmental factors. Brain-scan studies show that the neural circuitry that normally responds to the pleasurable, rewarding aspects of eating doesn't seem to work in anorexics.

The Body Project study, which is funded by the National Institutes of Health, recruited participants by distributing flyers outside classrooms and posting them in school bathrooms. Now sororities and other groups are beginning to launch peer-administered versions of the program. But even if one is not available in your community, there are things parents can do to help with body-image issues. Be aware of what signals you might be giving your children when you talk about your own desire to lose weight. Pay attention to the stereotypical body image your kids are watching on TV. And perhaps most important, talk with them about it.

Sanjay Gupta's Fit Nation series airs on House Call on CNN, Saturdays and Sundays, at 8:30 a.m. E.T.

—With reporting by Shahreen Abedin

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