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Health Capsules
May 2006
Low-Calorie Diet May Slow Aging

There’s been a lot of buzz on the web about using a low-calorie diet to live longer.  The technique works in creatures from fruit flies to rats, mice and monkeys, but no one knows if it can do the same for people.  A new study of overweight people who cut their calories by 25% for 6 months found some promising lab results that have been linked to longevity.  The results aren’t enough for any major conclusions, but they point the way toward longer studies to see if low-calorie diets can really slow the aging process in people.

NIH-funded researchers at Louisiana State University studied 48 healthy men and women who did not have active lifestyles.  They were randomly divided into 4 groups:

• One group stayed on a diet to maintain their pre-study weight.
• A calorie-restriction group ate 25% less calories.
• A calorie-restriction with exercise group ate 12.5% less calories but exercised to burn 12.5% more.
• A very low-calorie diet group ate 890 calories a day until they lost 15% of their weight.  They then followed a weight-maintenance diet to hold the lower weight.

By the end of 6 months, there were changes in 2 important measures that have been linked to longer lives in humans.  Fasting insulin levels were significantly lower in all 3 groups on the restricted-calorie diets.  Core body temperature was reduced in both the calorie-restriction and calorie-restriction with exercise groups.  The low-calorie diets may also affect some other measurements of metabolism that have been linked with living longer and aging.

This study was a small pilot project for a long-term study called the Comprehensive Assessment of Long-Term Effects of Reducing Intake of Energy (CALERIE).  CALERIE, which is sponsored by NIH’s National Institute on Aging (NIA), will test the effects of lowering caloric intake for 2 years in a larger number of people.  It’s set to start later this year.

Definitions iconDefinitions
A measure of the energy stored in food.  When you eat more calories than your body can use, it stores that extra energy as fat.

Links iconWeb Sites

Low-Calorie Diet : HealthInformation/ Publications/ AgingUndertheMicroscope/ chapter04.htm

  Progress Toward Avian Flu Vaccine  

Avian flu viruses from a class called H5N1 have now infected birds throughout Southeast Asia and are spreading into Central Asia, Africa and Europe.  They’ve infected some people, too.  So far, the viruses can’t move easily from person to person, but if they learned how it could cause a global outbreak.  Results from a new study funded by NIH show that researchers may be on the path to develop a vaccine to protect people.

The vaccine they tested was made from an H5N1 virus that was changed so it can’t infect people.  Researchers assigned 451 healthy adults between 18 and 64 years old at random to 5 groups.  Each received 2 shots about a month apart of either a placebo or 1 of 4 different doses of the vaccine.  Their blood was collected and tested to see what amounts of the virus-fighting molecules called antibodies their bodies had made.

The higher the dose of vaccine, the more antibodies people produced.  Of those in the highest-dose group, a bit more than half produced levels of antibody that the researchers predict would neutralize the virus.  Almost all the side effects were mild.

Although some hoped that the vaccine might work better than it did, these results are still a step in the right direction, according to Dr. Anthony S. Fauci, director of NIH’s National Institute of Allergy and Infectious Diseases.  Researchers are now testing several ways to make a more effective H5N1 vaccine, including adding immune boosters known as adjuvants to try to stimulate better antibody production.

Definitions iconDefinitions
A look-alike substitute with no active ingredients.  Used to compare how well an experimental treatment works.

Links iconWeb Sites

Avian Flu :   focuson/ flu/default.htm


Links iconFeatured Web Site

Visible Proofs

Visible Proofs traces the history of forensic medicine—the efforts of physicians, surgeons and other specialists to translate views of bodies and body parts into hard evidence or “visible proofs” that testify on behalf of the victims of violent crime. The site includes online galleries activities and lesson plans.

From NIH’s National Library of Medicine.

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