Vitamine
D tegen tuberculose.*
Een tabletje vitamine D, wel 2,5 mg groot, lijkt het immuunsysteem in het lichaam zo te verhogen dat bacteriën zoals de bacterie die tuberculose veroorzaakt, zes weken lang geen kans hebben. Dit blijkt uit een Engelse laboratoriumstudie met 192 gezonde mensen, die in aanraking waren geweest met een TBC-patient. Zij kregen al of niet die ene dosis vitamine D. Met bloedmonsters werden de testen uitgevoerd. Omdat uit onderzoek al gebleken is dat mensen met TBC lage bloedwaarden aan vitamine D hebben is het belangrijk nu een echt onderzoek onder mensen te houden over de effecten van vitamine D en het voorkomen van TBC.
Low-cost
vitamin D supplement blocks tuberculosis (TB) for six weeks after a single dose
Scientists have shown
that a single 2.5 mg dose of vitamin D may be enough to boost the immune system
to fight against tuberculosis (TB) and similar bacteria for at least 6 weeks.
Their findings came from a study that identified an extraordinarily high
incidence of vitamin D deficiency amongst those communities in London most at
risk from the disease, which kills around two million people each year.
The research, funded by the Wellcome Trust, the Department of Environmental
Health at Newham Council and Newham University Hospital NHS Trust Respiratory
Research Fund, is published online in the American Journal of Respiratory and
Critical Care Medicine.
Whilst a diet of oily fish can provide some vitamin D, the main source of the
body's vitamin D comes from exposing the skin to sunlight. In Britain, however,
the amount of sunlight is usually insufficient to make vitamin D in the skin
between October and April, and much of the population becomes deficient during
the winter and spring.
Researchers from Queen Mary's School of Medicine and Dentistry, London, and the
Wellcome Trust Centre for Research in Clinical Tropical Medicine, Imperial
College London, studied patients at Newham University Hospital and Northwick
Park Hospital in London who had been exposed to TB. They found that over 90% of
such patients had a vitamin D deficiency.
Vitamin D was used to treat TB in the pre-antibiotic era, when special sanatoria
were built in sunny locations, such as the Swiss Alps. But until now, no study
has evaluated the effect of vitamin D supplementation on immunity to
mycobacteria, the family of bacteria that cause TB.
The researchers performed a randomised control trial on a group of volunteers
who were given either a 2.5mg supplement or a placebo. Samples of the volunteers'
blood were then tested in Dr Robert Wilkinson's Wellcome Trust-funded laboratory
at Imperial College, to see whether the supplement affected the immune system's
ability to withstand infection by mycobacteria.
"We found that a single large dose of vitamin D was sufficient to enhance a
person's immunity to the bacteria," says Dr Adrian Martineau from the
Division of Medicine at Imperial College London, who co-ordinated the study.
"This is very significant given the high levels of vitamin D deficiency in
people at the highest risk of TB infection, and shows that a simple, cheap
supplement could make a significant impact on the health of people most at risk
from the disease."
According to the Health Protection Agency, the incidence of TB in the UK is
increasing, with around 8,000 new cases a year. Cases in the UK are
predominantly confined to the major cities and about 40 per cent of all cases
are in London. TB is also a major global problem: an estimated one-third of the
world's population – nearly two billion people – are infected. Nine million
people a year develop the active disease worldwide, which kills two million each
year.
"Most cases of TB in London arise from people who have already become
infected with the bacteria but in whom it lies latent," says Professor
Chris Griffiths from Queen Mary’s School of Medicine and Dentistry. "Our
results indicate that vitamin D supplementation may prevent reactivation of
latent TB. Identifying people with latent TB and providing supplements could be
an important strategy for tackling the disease."
Treatment is both very cheap – about 60p per dose or 10p per week – and
safe. Vitamin D supplements could be prescribed for patients with or at risk of
latent TB through GP surgeries.
Dr Martineau points out: "Our work adds to the growing evidence that
vitamin D may have a wide range of important health benefits, including
preventing falls and fractures and reducing risk of cancer and diabetes, as well
as boosting the immune system against infection. Population-wide supplementation
needs to be considered by public health planners."
"Milk and orange juice could be fortified with vitamin D, as in the US and
Canada," he says. "At present only margarine is supplemented in the
UK, and recent studies show that this is not an effective way to prevent vitamin
D deficiency." Free
abstract
(Juni 2007) (Opm.
Omega-3 vetzuren al tijdens de zwangerschap blijken uit eerdere
onderzoeken ook heel belangrijk te zijn voor de ontwikkeling van de foetus.)