Lab Report: Health, Science and Medicine

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Roderick Chen/All Canada Photos/Corbis

NUTRITION

New Guidelines for Vitamin D and Calcium

In recent years, ominous reports from health officials have warned that the majority of Americans are deficient in calcium and vitamin D. But a new government-commissioned analysis concludes that those claims were exaggerated--for vitamin D in particular--and, for the first time, establishes a recommended dietary allowance (RDA) for the two nutrients.

For the protection of bone health, the report sets the daily RDA for most adults at 600 IU for vitamin D and 1,000 mg for calcium. And it concludes that most Americans get the appropriate amounts without supplementing. While extra vitamin D has been linked with prevention of cancer, heart disease and diabetes, the report's authors say the scientific data are too weak to recommend it for those purposes. They also stress that megadoses of vitamin D, which some experts believed could enhance D's health benefits, are not effective and could even be harmful. The authors issued a similar warning against the practice of spending more time in the sun to promote the synthesis of vitamin D in the skin through UV rays.

CANCER

MRI Detects More Tumors in Breast-Cancer Patients

Screening, as every cancer survivor knows, is a critical part of treatment, since early detection of new or recurrent tumors is a priority for staying cancer-free. So for breast-cancer patients as well as healthy women with cancer risk factors, that means annual mammograms to spot the first shades of a tumor.

A new study of more than 1,000 women suggests that some women may benefit even more by adding a second screening tool--MRI--to their annual X-ray mammogram. In women previously diagnosed with breast cancer, the study found, yearly screening with MRI and mammograms caught twice as many instances of cancer as it did in women who had never had the disease. Currently, the magnet-based MRI is recommended only for healthy women with cancer risk factors such as a family history or the BRCA-1 or BRCA-2 genetic mutations for breast cancer. Until now, studies haven't supported adding MRI to annual screenings of cancer survivors; although the technology can provide more-detailed views of dense tissue, it also leads to more false positives.

The new results suggest that expanding MRI screening to breast-cancer survivors may help detect more cancer, but experts say additional studies need to confirm that benefit first.

FROM THE LABS

Reversing Aging

Until recently, the idea of turning back time seemed biologically impossible. But new research on telomeres--pieces of DNA that cap chromosomes--has brought science fiction closer to reality. Telomeres in aging cells start to shrink, but a study of prematurely aged mice found that boosting levels of an enzyme that maintains telomere length restored fertility, reversed age-related nerve-cell deterioration and helped regenerate certain tissues.

Why Pins Ease Pain

Acupuncture is a godsend for many, especially when it comes to pain relief. But how does it work? A new study involving brain scans suggests that the carefully placed pricks may change the way the brain's neurons process pain, lending support to the notion that the ancient practice's benefits are entirely in your head.

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