Thu 16 Sep 2004
Millions Deficient in Vital Vitamin D, Experts Warn
By John von Radowitz, Science Correspondent, PA News
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Millions of Britons are deficient in a vitamin that protects against a host of diseases including rickets, diabetes and cancer, it was claimed today.
Experts called for urgent action to raise vitamin D levels, particularly among pregnant women, young children, and people with dark skin.
They suggested that one remedy might be widening vitamin D fortification of food, possibly to include bread and milk.
At present only breakfast cereals and margarines are fortified with vitamin D in the UK.
The experts also recommended taking vitamin D supplements such as cod liver oil capsules.
Fear of the sun and an "indoor" culture were both said to have contributed to vitamin D deficiency in Britain and other western countries.
About 80% of the vitamin obtained in the body is synthesised through the conversion of chemicals in the skin by sunlight.
But in Britain, from October to the end of March, the sun is too weak to produce any vitamin D.
Professor Graham Bentham, from the University of East Anglia, said: "During these winter months we rely on what we have stored in our body from summer exposure and what we get from diet."
Although oily fish and egg yolk are good sources of the vitamin, it is not abundant in many foods.
The importance of vitamin D to all-round good health has only come to be recognised in the last two decades, the experts said.
Before then it was only thought to benefit the bones, and in particular protect against rickets.
Today it was clear that vitamin D deficiency was associated with a wide range of diseases, and that the vitamin was needed in higher doses than previously thought.
Dr Birgit Teucher, from the Institute of Food Research in Norwich, who joined three colleagues to talk about vitamin D in London today, said: "Since the 1980s it has become increasingly apparent that vitamin D has important roles apart from its effects on bone.
"Shortage of vitamin D may be associated with a whole range of diseases, including muscle weakness, hypertension, auto-immune diseases including multiple sclerosis, certain types of cancer, and cardiovascular disease."
There was evidence that the vitamin protected against breast, prostate ovarian and colon cancer, and had a major impact on diabetes.
It also reduced tissue damage caused by certain infections such as tuberculosis, leprosy and gum disease, as well as rheumatoid arthritis.
Diabetes expert Dr Barbara Boucher, from St Bartholomew's and the London Queen Mary School of Medicine and Dentistry, said vitamin D was needed for insulin to be released effectively.
Worldwide there had been an "explosion" of Type 2 diabetes, which was four times greater in black and Asian people living in the West. People with dark skins were less able to manufacture their own source of vitamin D from the sun.
Rates of insulin-dependent Type 1 diabetes were also rising "like mad", said Dr Boucher.
Three different studies had shown that vitamin D supplements given to breastfeeding mothers and young children reduced the incidence of Type 1 diabetes by 60% between birth and the age of 30.
Dr Boucher also pointed to increased rates of colon and prostate cancer as evidence of a lack of vitamin D in the population.
Professor Brian Wharton, from the Institute of Child Health in London, said there were many reports of rickets making a comeback, especially among Asian and Afro-Caribbean children.
He believed an over-reaction to "cover up" campaigns aimed at protecting people from skin cancer was partly responsible for the nationwide lack of vitamin D.
"I think it has played a role," he said.
"There's certainly no doubt that if you wear sunscreen vitamin D conversion goes down.
"I'm certainly not promoting sun `bingeing' but we do need some sensible use of the sun, and we've been swinging too strongly against it."
Dr Boucher said the way many people spent much of their lives indoors may be another factor.
"Indoor activities, such as working out in the gym or sitting at computers all day, might contribute to vitamin D deficiency," she said.
Lack of exercise could also be involved, since fat acted as a "sink" which soaked up and stored vitamin D.
However she and other experts warned against seeking a solution from the sun. The UVB rays that produced vitamin D also caused skin cancer, and the disease was on the increase.
In 2003 there were 1,600 deaths from skin cancer in the UK, a rise of 7% on the previous year.
All agreed that dietary intake of vitamin D had to be increased.
In the United States milk was fortified with the vitamin, but not sufficiently. New studies had looked at the possibility of fortifying orange juice and bread.
But care had to be taken not to overdose the population. Very high levels of vitamin D could be toxic, leading to kidney and brain damage.
There is currently no recommended level of vitamin D intake between the ages of four and 64.
Infants are supposed to get about 10 micrograms a day but on average receive three to four micrograms.
Professor Bentham suggested that everyone should be taking about 12.5 micrograms of the vitamin.
Dr Boucher thought the right level was more than 5 micrograms and less than 25.
She said: "The one message that should come out of all this if you want to reduce the burden of chronic disease in years to come is that no-one should be short of vitamin D."