Researchers from the Peninsula Medical
School, the University of Cambridge and the University of Michigan,
have for the first time identified a relationship between Vitamin
D, the "sunshine vitamin", and cognitive impairment in a
large-scale study of older people. The importance of these findings
lies in the connection between cognitive function and dementia:
people who have impaired cognitive function are more likely
to develop dementia. The paper will appear in a forthcoming
issue of the Journal of Geriatric Psychology and Neurology.
The study was based on data on almost 2000 adults aged 65 and
over who participated in the Health Survey for England in 2000
and whose levels of cognitive function were assessed. The study
found that as levels of Vitamin D went down, levels of cognitive
impairment went up. Compared to those with optimum levels of
Vitamin D, those with the lowest levels were more than twice
as likely to be cognitively impaired.
Vitamin D is important in maintaining bone health, in the absorption
of calcium and phosphorus, and in helping our immune system.
In humans, Vitamin D comes from three main sources - exposure
to sunlight, foods such as oily fish, and foods that are fortified
with vitamin D (such as milk, cereals, and soya drinks). One
problem faced by older people is that the capacity of the skin
to absorb Vitamin D from sunlight decreases as the body ages,
so they are more reliant on obtaining Vitamin D from other sources.
According to the Alzheimer's Society, dementia affects 700,000
people in the UK and it is predicted that this figure will rise
to over 1 million by 2025. Two-thirds of sufferers are women,
and 60,000 deaths a year are attributable to the condition.
It is believed that the financial cost of dementia to the UK
is over £17 billion a year.
Dr. Iain Lang from the Peninsula Medical School, who worked
on the study, commented: "This is the first large-scale study
to identify a relationship between Vitamin D and cognitive impairment
in later life. Dementia is a growing problem for health services
everywhere, and people who have cognitive impairment are at
higher risk of going on to develop dementia. That means identifying
ways in which we can reduce levels of dementia is a key challenge
for health services."
Dr Lang added: "For those of us who live in countries where
there are dark winters without much sunlight, like the UK, getting
enough Vitamin D can be a real problem - particularly for older
people, who absorb less Vitamin D from sunlight. One way to
address this might be to provide older adults with Vitamin D
supplements. This has been proposed in the past as a way of
improving bone health in older people, but our results suggest
it might also have other benefits. We need to investigate whether
vitamin D supplementation is a cost-effective and low-risk way
of reducing older people's risks of developing cognitive impairment