Following my last post I was interested to read a well researched review paper (1) that looks into the link between vitamin D deficiency and the development of dementia. The report is published in the May issue of the Journal of Alzheimer’s disease and is written my William B Grant PhD of the Sunlight, Nutrition and Health Research Centre (SUNARC). SUNARC is an organization devoted to research and education relating to the prevention of chronic disease through changes in diet and lifestyle. I have previously mentioned SUNARC when reporting on the importance of Vitamin D for health.
Previously I highlighted the link between vitamin D and the brain when I wrote about the potential use of the sunlight vitamin for helping sufferers of SAD (seasonal affective disorder) and also possible link between low vitamin D levels in those suffering from depression and mood disorders.
William Grant, the author of the paper, begins by highlighting the rise in individuals who are suffering with dementia in the Western world. The condition deserves attention since the number of people living into old age is increasing and it is a worthwhile aim to help individuals achieve lasting health as they age so they may live life to the full. There are several risk factors for the development of Alzheimer’s disease and vascular dementia. Based on an increasing number of studies linking these risk factors with Vitamin D deficiency, the article(1) suggests that further investigation of possible direct or indirect linkages between Vitamin D and these dementias is certainly needed. Diet and lifestyle are being increasingly researched in relation to their links with dementia prevention and vitamin D is gaining attention for its role in many condition from heart disease, diabetes, bone health, cancer, infections, chronic fatigue and more.
Low blood serum levels of vitamin D have been associated(1) with increased risk for several diseases which are also considered risk factors for the development of dementia or are often reported to precede the incidence of dementia e.g. cardiovascular diseases, diabetes mellitus, depression, dental caries, osteoporosis, and periodontal disease. These studies are only observational studies,nproviding medical researchers with links between vitamin D and dementia. As yet there no randomised controlled trials to draw evidence from.
The way that vitamin D may be working to protect the brain is via several mechanisms. It seems to be able to act by protecting the neurones in the brain (brain nerve cells), it may also be protecting the blood vessels in the brain and having an effect by protecting against excess calcium entry into the brain. Vitamin D also seems to act as an anti-inflammatory – an important factor since dementia is often linked to inflammation in the brain and body (1). There is also plenty of evidence to suggest an important role for vitamin D in brain development and function.
Writing in the article, Dr. Grant states, “To date, the evidence includes observational studies supporting a beneficial role of vitamin D in reducing the risk of diseases linked to dementia such as vascular and metabolic diseases, as well as an understanding of the role of vitamin D in reducing the risk of several mechanisms that lead to dementia.” “However, until RCTs are performed, the hypothesis cannot be considered a fact”
A recent analysis(2) found that there is a global widespread insufficiency of vitamin D and there is evidence from the National Diet and Nutrition Surveys (NDNS) which suggests that in the UK deficiency of this vital nutrient is a real problem (3,4,5,6). The problem is made worse in the older generations, as we age our bodies find it increasingly difficult to manufacture vitamin D. In the UK many of us do not get enough sunlight exposure to generate decent levels of vitamin D in our bodies, especially in the autumn and winter months when we cover our bodies up and don’t get out during the daylight hours very often.
Only small amounts of vitamin D are found in food sources such as oily fish (mackerel, salmon and sardines) and egg yolks. As many of us in the UK are falling short of recommended vitamin D levels, if you rarely get out into the sun, you may wish to consider a vitamin D supplement which provides around 12mcg/day (around 500iu a day). Such a supplement may be particularly useful during the autumn and winter months.
For more interesting information about the benefits of vitamin D and sunlight for health please visit the SUNARC website, the information there is well presented and backed up by significant amounts of good evidence.
(1)Grant, WB. 2009. Does Vitamin D Reduce the Risk of Dementia? Journal of Alzheimer’s Disease 17:151-159.
(2)Hagenau T et al. 2008. Global vitamin D levels in relation to age, gender, skin pigmentation and latitude: an ecologic meta-regression analysis. Osteoporosis International May [E publication ahead of print]
(3) Finch S et at. 1998. National Diet and Nutrition Survey of People aged 65 Years and Over. London: H. M. Sationery Office.
(4) Gregory L et al. 2000. National Diet and Nutrition Survey of People aged 4-18 years. Vol 1. Report of the Diet and Nutrition Survey. London: The Stationery Office
(5) Henderson L et al. 2002. National Diet and Nutrition Survey: Adults Aged 19-64 years. Vol 1: Types and Quantities of Foods Consumed. London: The Stationery Office
(6) Hypponen E & Power C. 2007. Hypovitaminosis D in British adults age 45y: nationwide cohort study of dietary and lifestyle predictors. Am J Clin Nutr. 85:860-888.
Written by Ani Kowal
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