Lack of vitamin D in pregnancy suspected as cause of MS

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Birth date in May linked to higher risk of MS

Lack of vitamin D in pregnancy suspected

http://www.theglobeandmail.com/servlet/ArticleNews/TPStory/LAC/20041207/MS07/TPS\

cience/

 

By PATRICIA REANEY

Reuters News Agency

Tuesday, December 7, 2004 - Page A6

 

 

LONDON -- People born in May in the Northern Hemisphere have a higher

than average risk of developing multiple sclerosis, researchers said

yesterday.

 

An analysis of data from studies of more than 42,000 people in Canada,

Britain, Denmark and Sweden showed that May babies have a 13-per-cent

higher chance of developing the illness later in life, but that those

born in November birthday have a chance 19-per-cent lower.

 

" If you are born in May, your risk is higher than any other month, and

if you are born in November, your risk is lower than any other month, "

George Ebers, of Radcliffe Infirmary at the University of Oxford, said

in an interview.

 

The effect was similar in all the countries but most prominent in

Scotland, which has the highest rate of multiple sclerosis in the world,

Professor Ebers said.

 

Although the scientists cannot explain the correlation between birth

month and MS, they suspect it could be linked to exposure to sunlight

and the mother's vitamin D levels, which could influence the child's

development.

 

Shorter days during the winter months in the Northern Hemisphere limit

the amount of sunlight women are exposed to during pregnancy.

 

The body makes vitamin D from the action of sunlight on skin. Foods such

as oily fish and egg yolk are rich in the vitamin.

 

" It looks like something must be happening very early, either in

gestation or around the time of birth, that determines one's subsequent

risk of getting MS, " Prof. Ebers added. MS occurs when immune system

cells attack and destroy the myelin sheath that protects the nerve cells

in the brain and spinal cord. The cause of the illness is unclear.

Scientists believe it may be a combination of genetic, dietary and

environmental factors.

 

The ailment is rare in Africa and most common in people living in colder

countries. It is most often diagnosed in people between the ages of 20

and 50.

 

More women than men have MS, which can be difficult to diagnose because

symptoms such as tingling, fatigue, loss of balance and slurred speech

are intermittent.

 

Prof. Ebers and his colleagues compared birth months of 17,874 MS

patients in Canada and 11,502 in Britain with those of unaffected

siblings and the general population.

 

They pooled their findings with data from studies in Denmark and Sweden.

 

" The risk factors responsible for the effect of timing of birth must

vary seasonally and probably interact with development of the central

nervous system or immune system, or both, " they said in a report

published on-line by the British Medical Journal.

 

They added that the findings could partly explain the increased risk of

MS in the children of Asian and Caribbean immigrants to Britain.