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Vitamin D: key to muscle and bone strength, independence: a deficiency in vitamin D could impair your mobility and activities of daily living.

Up to 90 percent of older adults are vitamin D-deficient, leading to loss of mobility and inability to undertake activities of daily living (ADL), according to new research findings released from the Netherlands. The deficiency can lead to brittle, osteoporotic bones, which enhances the risk of serious falls, culminating in the need for admission to a nursing home or assisted living facility, and severely impacting elders' independence and quality of life. The study data was drawn from an ongoing Dutch study, The Longitudinal Aging Study Amsterdam.

PRESERVING MUSCLE STRENGTH IS IMPORTANT.

"Seniors who have low levels of vitamin D are more likely to have mobility limitations and to see their physical functioning decline over time," said lead author Evelien Sohl, MSc, of the VU University Medical Center in Amsterdam. Adults with these limitations "are more likely to be admitted to nursing homes and face a higher risk of mortality," she added. Because of this, preserving muscle strength is important.

SYMPTOMS OF VITAMIN D DEFICIENCY. Muscle weakness is generally noticed in the proximal muscle groups--those closest to the body's mid-line--and manifests with a feeling of heaviness in the legs, being easily fatigued, and difficulty climbing stairs and getting up from a chair. This weakness is reversible with vitamin D supplementation.

SOURCES OF VITAMIN D. While many people get the majority of their vitamin D through exposure to the sun (the body synthesizes sunlight to produce the vitamin), the ability to synthesize grows weaker as people age. In addition, those who live in climates above latitude 35 sometimes lack sufficient sunlight to manufacture their own vitamin D, particularly in winter.

HEALTHY DIET. Insufficient dietary intake is a culprit as well--vitamin D also is derived from a limited variety of food sources, such as fatty fish (salmon, tuna, mackerel, sardines), beef liver, cheese, egg yolks, and mushrooms that have been exposed to ultraviolet light under controlled conditions. Fortified foods provide most of the vitamin D in the American diet, for example, in milk, breakfast cereals, some orange juices and yogurt.

BOTTOM LINE. The available evidence shows that vitamin D supplementation preserves muscle strength and functional ability in frail, elderly people. Randomized trials are needed to further confirm these findings, the authors say.

RELATED ARTICLE: THE VIEW FROM DUKE

Clinicians Recommend Raising D Levels to 20 ng/ml

"Preventing frailty and functional decline with aging is a major and pressing goal for the research community. The recent epidemiological study from the Netherlands further strengthens the association between low serum 25-hydroxyvitamin D (25(OH)D) levels and impaired function in older, community-dwelling people. Further, lower serum 25(OH)D levels are associated with worsening function over a three-year period. The unanswered question is whether supplementing older people with reduced serum 25(OH)D levels and impaired function will improve their performance. While most clinicians recommend vitamin D supplements to bring patients' serum levels to 20 ng/ml, whether this will improve function and reduce frailty must await ongoing clinical trials."

RELATED ARTICLE: FNB, USPSTF RECOMMENDED INTAKES FOR VITAMIN D

The Food and Nutrition Board (FNB) at the Institute of Medicine of The National Academies (formerly National Academy of Sciences) established a Recommended Dietary Allowance (RDA) for vitamin D representing a daily intake sufficient to maintain bone health and normal calcium metabolism in healthy people. RDAs for vitamin D are listed in both International Units (IUs) and micrograms (mcg); the biological activity of 40 IU is equal to 1 mcg. Even though sunlight may be a major source of vitamin D for some, the vitamin D RDAs are set on the basis of minimal sun exposure. For males and females age 51-70, RDAs are 600 IU (15 mcg); for males and females age 70+, RDAs are 800 IUs (20 mcg). However, the U.S. Preventive Services Task Force (USPSTF), a volunteer panel of national experts in prevention and evidence-based medicine, found Insufficient evidence to support vitamin D and calcium supplements at larger doses (greater than 400 IU of vitamin D3, and greater than 1,000 mg of calcium) to prevent fractures in older women. Further, the USPSTF found that lower doses of vitamin D and calcium supplements (less than 400 IU of vitamin D3 and less than 1,000 mg of calcium) do not prevent fractures in older adults and may increase the risk of kidney stones.

KENNETH W. LYLES, MD, Professor of Medicine; Director, Medicine Clinical Research Unit,; VA Medical Center, Duke
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Title Annotation:NEWSBRIEFS
Author:Lyles, Kenneth W.
Publication:Duke Medicine Health News
Geographic Code:4EUNE
Date:Oct 1, 2013
Words:737
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