More than one fourth of adults over 50 deficient in Vitamin D, finds study

According to researchers from Trinity College Dublin more than one fourth of adults over 50 years of age have deficiency of vitamin D.The research showed that over half (57%) had inadequate serum vitamin D levels, of which 26% were classed as vitamin D deficient.

The findings of the study were published in the international, peer-reviewed journal Nutrients.

This new research demonstrates that vitamin D deficiency is prevalent in older adult populations living at Northern latitudes and highlights the importance of public health strategies throughout midlife and older age to achieve optimal vitamin D status.

Vitamin D has a known role in bone health, with growing evidence for beneficial effects on muscle strength and other non-skeletal outcomes. It is known for being essential to bone health and its primary role is to help the body absorb calcium from the intestines to harden the bones. Not getting enough of the vitamin over long periods of time can lead to softening and weakening of bones.

Better understanding of factors that contribute to vitamin D deficiency is needed to identify people most at-risk. Determinants of deficiency identified in this new study were female gender, advanced age (80+ years), smoking, non-white ethnicity, obesity and poor self-reported health. Researchers therefore identified a profile of older people more likely to be at risk of vitamin D deficiency. Being of a healthy weight, retired, engaging in regular vigorous physical activity, vitamin D supplement use, sun travel in past 12 months and summer season were positive determinants, and therefore potentially protective factors against vitamin D deficiency in older people.

The findings were based on 6004 midlife and older adults, living at Northern latitudes (England, 50-55oN) derived from the English Longitudinal Study of Ageing (ELSA). Since UVB radiation (sunlight) is a known determinant of vitamin D status, this was investigated. Interestingly, residents in the South of England had a reduced risk of deficiency, compared with the North, even after adjustment for socioeconomic and other predictors of vitamin D status.

Associate Professor in Nutrition at Trinity College, Maria O'Sullivan commented 'Our study identified factors associated with vitamin D deficiency, including being aged 80+ years, obesity and sedentary lifestyles; all of which are increasing traits in western populations. Furthermore, this is one of the few studies to highlight the importance of non-white ethnicity in vitamin D deficiency in a large study of ageing. The findings are valuable in developing targeted strategies to eliminate vitamin D deficiency (at 30nmol/L) in older populations'.

First Author Dr Niamh Aspell, who conducted the study as part of her PhD at Trinity said: 'Those who used a vitamin D supplement, were less likely to be vitamin D deficient as may be expected, but supplement use was low (4.4%) and, therefore, food fortification and other strategies need to be considered at policy level for older populations'.

Co-Author and Trinity Research Fellow Dr Eamon Laird, said: 'The high rates of deficiency are similar to rates seen in other high latitude countries such as Ireland. However, other more northern countries such as Finland have implemented a successful vitamin D fortification policy which has all but eliminated deficiency in the population. Such a policy could easily be implemented in the UK and Ireland '.