Vitamin D and Ageing (29 page chapter, VDR decreases with age)

Vitamin D and Ageing

Biochemistry and Cell Biology of Ageing: Part I Biomedical Science pp 191-220

Tom R. Hill. Antoneta Granic, Terence J. Aspray

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One hundred years has passed since the discovery of vitamin D as the active component of cod-liver oil which cured the bone disease rickets. Since then our knowledge of vitamin D has expanded tremendously and has included recognition of the importance of UV radiation as a source of the vitamin as well as the discovery of the vitamin as a nutrient, a pro-hormone and a potent steroid hormone with a major role in calcium and bone metabolism. In the last 25 years or so, the discovery of the vitamin D receptor in over 30 different body tissues together with the existence of the alpha-1-hydroxylase enzyme in these tissues provided evidence of a pleiotropic role of vitamin D outside its classical role in the skeleton. These important discoveries have provided the basis for the increasing interest in vitamin D in the context of nutritional requirements for health including the prevention of chronic diseases of ageing. The recent publication of the Dietary Reference Intake report on vitamin D and calcium by the North American Institute of Medicine (IOM) is the most comprehensive report to date on the basis for setting nutritional requirements for vitamin D. This chapter will summarize the nutritional aspects of vitamin D and discuss the changes in vitamin D metabolism and requirements with ageing. It will summarize key evidence on the relationship between vitamin D status and some of the main ageing related health outcomes including bone, muscle and cognitive health as well as survival focusing on the published literature in very-old adults (those >= 85 years of age).

Clipped from PDF

Dermal Vitamin D Production

The dermal capacity to produce vitamin D in persons aged 65 years has been estimated to be about 25% of that in persons aged 20-30 year s exposed to the same amount of sunlight (Holick et al. 1989; MacLaughlin and Holick 1985). This reduction cannot be explained by the decrease in mass of the epidermis with ageing, but rather seems to be related to the reduction in the concentration of skin 7-dehydrocholesterol. Other indirect factors which affect exposure to sunlight in older adults include the wearing of more concealing clothing (Matsuoka et al. 1992), an increased use of sunscreen (Holick 1994), and reduced sun exposure, arising from less physical activity and time outdoors compared with younger age groups (Health Survey for England 2008).

Changes in VDR Numbers

Vitamin D deficiency is associated with muscle weakness which potentially increases the risk of falls and fractures, possibly mediated through effects on 1,25(OH)2D3 receptors which have been discovered in muscle (Simpson et al. 1985; Bischoff et al. 2001). Bischoff-Ferrari et al. demonstrated a strong negative correlation between age and VDR expression in muscle as measured by the number of VDR-positive nuclei per 500 counted nuclei (Bischoff-Ferrari et al. 2004). This association was independent of biopsy location and circulating 25(OH)D concentrations. This finding may have significant clinical ramifications in older age owing to the importance of 1,25(OH)2D3 in regulating transcription of muscle related genes. The role of vitamin D in muscle atrophy in older adults has been reviewed by Dawson- Hughes (2012) and will be discussed later in this chapter.

See also VitaminDWiki Aging leads to a decrease of vitamin D getting to cells – Sept 2017