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Vol. LXIV, No. 19
September 14, 2012
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Digest

Study Finds Calorie Restriction Does Not Affect Survival

Scientists have found that calorie restriction does not extend years of life or reduce age-related deaths in a 23-year study of rhesus monkeys.
Scientists have found that calorie restriction does not extend years of life or reduce age-related deaths in a 23-year study of rhesus monkeys.

Scientists have found that calorie restriction—a diet consisting of approximately 30 percent fewer calories but with the same nutrients of a standard diet—does not extend years of life or reduce age-related deaths in a 23-year study of rhesus monkeys. However, calorie restriction did extend certain aspects of health. The research, conducted by scientists at the National Institute on Aging, was reported in the Aug. 29 online issue of Nature.

Calorie restriction research has a long history. The first finding came in the 1930s, when investigators observed that laboratory rats and mice lived up to 40 percent longer when fed a calorie-restricted diet. Subsequent research has cited calorie restriction as extending lifespan of yeast, worms, flies and some strains of mice. But other studies have not shown a longevity benefit. For example, in studies of certain strains of mice, calorie restriction on average had no effect on lifespan. Some of these mice actually had a shorter lifespan when given a calorie-restricted diet. To date, research does not provide evidence that calorie restriction is an appropriate age regulator in humans, the NIA investigators point out. Currently, limited human studies are under way to test the effectiveness and safety of calorie restriction in people.

The “results suggest the complexity of how calorie restriction may work in the body,” said NIA director Dr. Richard Hodes. “Calorie restriction’s effects likely depend on a variety of factors, including environment, nutritional components and genetics.”

Protein Linked to Increased Risk of Heart Failure, Death in Older Adults

A protein known as galectin-3 can identify people at higher risk of heart failure, according to new research supported by the National Heart, Lung, and Blood Institute. The research is based on work from NHLBI’s Framingham Heart Study, which began in 1948 and has been the leading source of research findings about heart disease risk factors.

“Galectin-3, a Marker of Cardiac Fibrosis, Predicts Incident Heart Failure in the Community,” was published online Aug. 29 in the Journal of the American College of Cardiology and will appear in the Oct. 2 print issue.

Heart failure occurs when the heart cannot fill with enough blood and/or pump enough blood to meet the body’s needs. Galectin-3 has recently been associated with cardiac fibrosis, a condition in which scar tissue replaces heart muscle, and cardiac fibrosis plays an important role in the development of heart failure.

Heart failure carries enormous risk for death or a lifetime of disability and often there are few warning signs of impending heart failure. Measuring levels of galectin-3 in the blood may offer a way to identify high-risk individuals who could benefit from treatments to prevent debilitating heart failure and death. Early identification of predisposed individuals would allow treatment to begin long before heart failure develops and could help people at high risk for heart failure to live longer, more active lives.

Stresses of Poverty May Impair Learning Ability In Young Children

The stresses of poverty—such as crowded conditions, financial worry and lack of adequate child care—lead to impaired learning ability in children from impoverished backgrounds, according to a theory by a researcher funded by NIH. The theory is based on several years of studies matching stress hormone levels to behavioral and school readiness test results in young children from impoverished backgrounds.

Further, the theory holds, finding ways to reduce stress in the home and school environment could improve children’s well-being and allow them to be more successful academically.

High levels of stress hormones influence the developing circuitry of children’s brains, inhibiting such higher cognitive functions such as planning, impulse and emotional control and attention. Known collectively as executive functions, these mental abilities are important for academic success.

Dr. Clancy Blair of New York University concludes that this altered stress response and its effect on executive function helps to explain one way in which poverty affects children’s development of school readiness skills and later classroom performance.

Although poverty is considered a major source of stress, the findings also suggest that other sources of stress may affect children in all income groups—for example, from divorce, harsh parenting or struggles with a learning disability.

The research was described in the September/October issue of Scientific American Mind, in an article by Blair.


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