Recent research has made us all increasingly aware that vitamin D plays a more vital role in health than was believed in the past. At the same time, over the last decade researchers have become increasingly aware that vitamin D deficiency is more common than previously thought, and they are beginning to see the consequences. One of the most recent findings comes from a new study in which low vitamin D levels were associated with an increased risk of seniors having trouble thinking clearly (cognitive impairment).
Seniors do better with D
The study, published in the Journal of Geriatric Psychiatry and Neurology, included 1,766 adults age 65 and older. A ten-question cognitive test addressing attention, orientation in time and space, and memory was used to determine whether participants were experiencing cognitive impairment, and a blood test was used to determine vitamin D status.
Vitamin D levels were higher in people with normal cognitive function than in people with cognitive impairment. The likelihood of cognitive impairment rose as vitamin D levels decreased, and those with the lowest vitamin D levels were more than twice as likely to be cognitively impaired as those with the highest levels. About half of those with cognitive impairment were in the group with the lowest vitamin D levels.
A virtuous vitamin
Vitamin D is a nutrient our bodies produce in response to sunlight exposure. Small amounts are found in foods such as fish, cod liver oil, eggs, and fortified dairy foods, but scientists are increasingly finding that dietary sources are not able to provide the amount of vitamin D needed for good health. Spending more time outdoors in the sun is an effective way to improve vitamin D status, but, because this increases the risk of skin cancers, many healthcare providers are recommending vitamin D supplements instead.
Poor vitamin D status has a long established link to high risk of osteoporosis and bone fractures. More recent evidence suggests that maintaining a healthy vitamin D status can protect against seasonal depression, heart disease, type 2 diabetes, some neurological diseases, and some cancers. Low vitamin D levels are especially prevalent among older people, in part because they tend to spend less time outdoors.
The results of this study don’t eliminate the possibility that low vitamin D levels are the result of cognitive impairment’s effect on outdoor activity and sunlight exposure; however, the findings provide important information as vitamin D intake recommendations for the elderly are reconsidered, and may help guide future research. “The relationship between low vitamin D levels and cognitive impairment underlines the importance of identifying micronutrient deficiencies in the elderly,” said lead study author Dr. David Llewellyn at the University of Cambridge in Cambridge, UK. “Further research will help to determine whether vitamin D supplementation is a cost-effective and safe way of reducing the incidence of cognitive impairment in the growing elderly population around the world.”
Current guidelines for vitamin D intake are 200 IU per day for children up to age 18,400 IU per day for adults from age 19 to 70, and 600 IU per day for those 71 and older. Some organizations representing healthcare professionals have begun calling for changes to these recommendations, particularly for children and the elderly, whose needs appear to be greater. The safe upper limit for vitamin D intake appears to exceed 2,000 IU per day for children and adults, but optimal amounts have yet to be determined.
(J Geriatr Psychiatry Neurol 2009; online publication)
Maureen Williams, ND
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