VOA慢速英语2010年-SCIENCE IN THE NEWS - Getting to the H

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STEVE EMBER:

This is the VOA Special English program SCIENCE IN THE NEWS. I'm Steve Ember.

BARBARA KLEIN:

And I'm Barbara Klein. This week, we will tell how less salt can lead to better health. We will also tell about the helpful effects of omega-three fatty acids. And, we will share details of recent studies about antidepressant drugs and running shoes.

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STEVE EMBER:

A small reduction in salt in your diet can be a big help to your heart. A new study used a computer model to predict how just three grams less a day would affect heart disease in the United States. The result was thirteen percent fewer heart attacks. It would lead to eight percent fewer strokes and four percent fewer deaths. The study predicted eleven percent fewer new cases of heart disease. And, two hundred forty billion dollars in health care savings¹.

The New England Journal of Medicine published a report about the study. The lead writer was Kirsten Bibbins-Domingo of the University of California at San Francisco. She says people would not even notice a difference in taste with three grams less salt per day.

BARBARA KLEIN:

Each gram of salt contains four hundred milligrams of sodium². The federal government says the average American man swallows ten grams of salt a day.

But the American Heart Association advises no more than three grams for healthy people. It says salt in the American diet has increased fifty percent since the nineteen seventies, while blood pressures have also risen. Less salt can mean a lower blood pressure.

New York City Mayor Michael Bloomberg is leading an effort called the National Salt Reduction Initiative. The idea is to put pressure on food companies and restaurants. Critics call it government interference. Mayor Bloomberg has already succeeded in other areas, like requiring fast food businesses in the city to list calorie information.

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STEVE EMBER:

Scientists know that omega-three fatty acids in fish oil can help people with heart disease live longer. Cold water fish like salmon³ and tuna contain omega-three fatty acids. These fatty acids are mainly found in fish oil. They are also in some vegetable oils and foods like walnuts⁴. Earlier studies showed that omega-three fatty acids can decrease the risk of coronary artery⁵ disease. But until now, no one knew why they are so helpful.

Coronary artery disease is a leading cause of death throughout the world. The disease results when plaque⁶ builds up inside coronary arteries⁷ and blocks the flow of blood to the heart.

BARBARA KLEIN:

Ramin Farzaneh-Far is an assistant professor of medicine at the University of California in San Francisco. He led a study to see if there might be a link between omega-three acids and the aging of cells. To do, his team examined telomeres -- the protective covers on the ends of chromosomes⁸. Scientists believe that the shortening of telomeres over time leads to cell death.

His research team measured the length of telomeres in blood cells from six hundred heart disease patients. The patients all had taken part in the Heart and Soul Study, which lasted from two thousand to two thousand two. Blood from the patients was tested for omega-three fatty acids.

Doctor Farzaneh-Far says his team wanted to see if there was any link between the fatty acid levels and the change in telomere length over time.

RAMIN FARZANEH-FAR: "Patients with the highest levels of omega-three fish oils were found to display the slowest decrease in telomere length, whereas those with the lowest levels of omega-three fish oils in the blood had the fastest rate of telomere shortening, suggesting that these patients were aging faster than those with the higher fish oil levels in their blood."

STEVE EMBER:

The Journal of the American Medical Association published the results of the study. The team did not study how much fish oil the patients were receiving, so the amount needed to have an effect is unclear.

Doctor Farzaneh-Far says the results confirm what the American Heart Association advises for patients with coronary artery disease. That is to eat fish two times a week, or have at least one gram a day of omega-three fish oil. Fish oil is not the only thing that can affect telomere length. But the researchers say it does have an influence. The researchers did not study the effect of omega-three fatty acids in people without heart disease. But they note that telomere shortening happens in everyone.

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BARBARA KLEIN:

Antidepressant drugs are often used to treat depression. They also are among the most commonly prescribed medicines in the United States. One study found that at least twenty-seven million Americans use antidepressants on doctors' orders. That number is two times what it was in the nineteen nineties.

Recently, researchers reported making discoveries that may change the way antidepressants are given to patients. Researchers at the University of Pennsylvania studied information from earlier studies about two drugs: paroxentine and imipramine. Both are commonly used against depression.

STEVE EMBER:

The studies involved more than seven hundred patients with severe, moderate and mild forms of depression. Some of the patients were given antidepressants. Others were given placebos¹⁰ -- harmless substances used in place of medication. The Journal of the American Medical Association reported on the results of the study. Jay Fournier was the lead writer.

JAY FOURNIER "What we found was that patients who are on the lower end of severity, the medications were not doing much more than the placebo⁹ was. For patients at the higher end of severity, the medications had a very potent¹¹ effect."

Doctors have been divided about how to treat patients with less serious signs of depression. The study does not offer suggestions for treatment, but it may affect treatment methods. The results may influence patients with milder signs of depression to seek other kinds of treatment. This is especially true since some antidepressants can have undesirable¹² side effects.

BARBARA KLEIN:

Antidepressant medicines can be extremely helpful for people with severe depression. This level of depression can make it difficult to work, sleep and eat normally.

Stuart Sotsky is a psychiatrist¹³ with George Washington University in Washington, D.C. He completed one of the studies used in the research. Doctor Sotsky says antidepressants can still help some moderately depressed¹⁴ patients. But his study showed that many others could do just as well with exercise, support groups and self-help methods.

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STEVE EMBER:

Finally, two studies are suggesting that modern running shoes could increase the risk of injuries to runners. One study involved sixty-eight healthy young women and men who ran at least twenty-four kilometers a week. The runners were observed on a treadmill¹⁵. Sometimes they wore running shoes while using the equipment. Other times the runners ran barefoot.

Researchers from the University of Colorado and the University of Virginia worked with a Virginia company -- JKM Technologies.

The researchers found that running shoes create more stress that could damage knees, hips¹⁶ and ankle joints¹⁷ than running barefoot. They observed that the effect was even greater than the effect reported earlier for walking in high heels.

The study appeared in the official scientific publication of the American Academy of Physical Medicine.

BARBARA KLEIN:

The other study appeared in Nature magazine. It compared runners in the United States and Kenya. The researchers were from Harvard University in Massachusetts, Moi University in Kenya and the University of Glasgow in Scotland. They divided the runners into three groups. One group had always run shoeless. Another group had always run with shoes. The third group had changed to shoeless running.

Runners who wear shoes usually come down heel first. That puts great force on the back of the foot. But the study found that barefoot runners generally land on the front or middle of their foot. That way they ease into their landing and avoid striking their heel.

STEVE EMBER:

Harvard's Daniel Lieberman led the study. He says the way most running shoes are designed may explain why those who wear them land on their heels. The heel of the shoe is bigger and heavier than other parts of the shoe, so it would seem more likely to come down first. Also, the heel generally has thick material under it to soften¹⁸ landings.

But the researchers do not suggest that runners immediately start running barefoot. They say it takes some training. And, there can be risks, like running when your feet are too cold to feel if you get injured.

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BARBARA KLEIN:

This SCIENCE IN THE NEWS was written by Caty Weaver¹⁹ and Brianna Blake. Our producer was Lawan Davis. I'm Barbara Klein.

STEVE EMBER:

And, I'm Steve Ember. Join us again next week for more news about science in Special English on the Voice of America.