“People aged 65 and over with high percent body fat have lower levels of 25-hydroxyvitamin D, the storage form of vitamin D, compared to those who have lower percent body fat,” says corresponding author Susan Harris, DSc, epidemiologist in the Bone Metabolism Laboratory at the USDA HNRCA.
Harris and co-author Bess Dawson-Hughes, MD, director of the Bone Metabolism Laboratory at the USDA HNRCA, interviewed 381 Caucasian men and women aged 65 and over about their sun exposure over a previous three-month period. Individuals reported how much time they spent outdoors, how much skin was exposed while outdoors, and whether or not they wore sunscreen. Seasonality, or when the individual entered the study, was also taken into account, because in Boston, where the study was conducted, sun rays are weak in winter compared with summer months. The researchers measured participants’ percent body fat using dual-energy x-ray absorptiometry (DXA), a precise method for determining body composition. Individuals were grouped into quartiles of percent body fat: less than 28 percent, 28 percent to 33 percent, 34 percent to 40 percent, and greater than 40 percent. Blood levels of 25-hydroxyvitamin D were measured and participants were asked to fill out a dietary questionnaire to measure the amount of vitamin D they obtained from food.Harris and Dawson-Hughes found that when adjusted for sex, age, seasonality and dietary vitamin D intake, 25-hydroxyvitamin D significantly decreased as body fat increased, (P
Vitamin D is called the “sunshine vitamin” because it is produced by the body when the skin is exposed to ultraviolet (UV) rays from the sun. Vitamin D can also be obtained from foods such as fish and fortified milk and from supplements. When this fat-soluble vitamin enters the body it is converted in the liver to 25-hydroxyvitamin D. This is one of several important forms of vitamin D, and is the form that researchers and clinicians use as an indicator of vitamin D status in individuals. “Vitamin D is especially critical in maintaining bone health, and there is evidence that many older Americans have low blood levels of vitamin D, which can put them at risk for bone fractures and osteoporosis,” says Dawson-Hughes, who is also a professor at Tufts University School of Medicine.
“These results cannot be carried over to other populations, such as young people, or elderly living in different climates. However, if low vitamin D stores are not attributed to low sunlight exposure in this population, it suggests that we should explore other possibilities,” says Harris. “The most likely explanation seems to be that vitamin D is sequestered in fat tissue, reducing its entry into the blood.”
Siobhan Gallagher | EurekAlert!
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21.09.2017 | Max-Planck-Institut für Hirnforschung
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
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Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
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Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems Holding GmbH about commercial use of a multi-well tissue plate for automated and reliable tissue engineering & drug testing.
MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems...
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