KEY POINTS:
Twenty minutes' lying in the sun could provide your best chance of avoiding colds and flu, according to new research which demonstrates that vitamin D, not vitamin C, provides the most efficient protection against cold viruses.
Vitamin D is created by the action of sunlight on the skin.
The malign consequences have been revealed in a study from the United States which shows that boosting vitamin D may be the most effective way of warding off infections that cause winter colds.
The authors, from Winthrop University Hospital, Mineola, New York, who publish their findings in the journal Epidemiology and Infection, say vitamin D stimulates "innate immunity" by activating peptides in the body that attack bacteria, fungi and viruses. "Vitamin D supplementation, particularly with higher doses, may protect against the typical winter cold and flu ... Since there is an epidemic of vitamin D insufficiency in the US, the public health impact of this observation could be great," they write.
Traditional advice has been to swallow large doses of vitamin C at the first sign of a sniffle. But the latest findings suggest we may have been turning to the wrong vitamin. The revelation is the latest addition to a long list of scientific studies highlighting the beneficent qualities of a previously underrated health resource.
Vitamin D has been described as "the wonder vitamin" after a 40-year review of research found a daily dose could halve the risk of breast and colon cancer. It has also been shown to play a vital role in heart disease, cancer, diabetes, high blood pressure, schizophrenia and multiple sclerosis as well as being essential for bone health.
Widespread deficiency in the vitamin among populations in the northern hemisphere suggests it may account for several thousand premature deaths from cancers alone, American scientists from the University of San Diego said in the American Journal of Public Health in December 2005. They reviewed 63 scientific papers and concluded "public health action" to boost vitamin D levels was needed.
High rates of heart disease in Scotland have been blamed on weak sunlight and short summers. Some experts believe the benefits of the Mediterranean diet have as much to do with the sun as with the regional food. The evidence of its role in fending off two of the commonest infections in the Western world - colds and flu - has come from research by US scientists who gave supplements of the vitamin to 208 women over three years. Half the women were given a 20-microgram dose of vitamin D, increased to 50 micrograms after two years, and the other half were given a placebo. Those who took the vitamin reported a 70 per cent reduction in colds and flu, from 30 episodes to nine over the three-year study.
All the women were Afro-Caribbeans who were being tested with vitamin D supplements to see if they prevented bone loss, which is a common problem following the menopause. People with dark skins make less vitamin D when exposed to the sun and consequently tend to have lower levels. The startling results offer a new motive to seek, in moderation, the sunlight.
Twenty minutes in the sun, with the hands, arms and face exposed, is all that is needed to get an adequate dose, but it needs to be regularly topped up through the summer. In winter the only way of maintaining levels is by taking cod liver oil or supplements.
Many countries have modified their warnings about the dangers of sunbathing in the light of the growing evidence for the benefits of vitamin D. Australia preached avoidance of the sun with its "slip, slap, slop" campaign. But the Association of Cancer Councils of Australia acknowledged two years ago that some exposure to the sun was necessary to achieve adequate vitamin D levels.
- INDEPENDENT
