Jakob Linseisen of the Helmholtz Center in Munich likes to sit outside in the sun after lunch and enjoy his cup of coffee. He never has the urge to lather on sunscreen first. And when he has to walk across campus of the environmental health research center for meetings with colleagues, he makes sure to push his shirtsleeves up so that a little sunlight gets on his arms.
Of course, Linseisen knows that too much exposure to ultraviolet light can cause skin cancer. But the nutritionist also worries that people are also getting too little direct sunlight. Ultraviolet rays help the skin produce the hormone vitamin D, which, among other things, leads to strong bones.
Linseisen and other experts contributed to a report released by the German Nutrition Society (DGE) concluding that most Germans suffer from vitamin D deficiencies. It recommends that older people, especially, should get an extra 20 micrograms of vitamin D daily, either through tablets or from sunlight.
With their advice, Linseisen and his colleagues have touched off a heated debate with dermatologists over whether or not it is justifiable to recommend that people spend more time in the sun. So far, the appeals made by dermatologists have served to keep people away from the cancer-causing UV rays.
"The debate over vitamin D deficiencies is extremely timely," confirms Dr. Jörg Reichrath, a senior physician in the dermatology department of Saarland University Medical Center, which also took part in the German Nutrition Society's study. "A lot is currently happening."
A working group of experts across Germany for dermatological prevention is also involved in the issue, and, along with other associations, will soon publish new recommendations.
Broken Bones and Rickets
In older people, studies show, a vitamin D deficiency leads to a higher risk of broken bones. Children without enough vitamin D are at risk of developing rickets, which is a painful softening of the bones that can lead to deformation. There have also been studies that show that people with higher vitamin D levels in their blood live longer.
Only about 10 percent of a person's level of vitamin D usually comes from his or her diet -- it is especially present in fatty fish. The rest needs to be absorbed from the sun through the skin. Rickets and the softening of bones became a worldwide problem at the start of the Industrial Revolution, when smog, basement apartments, and 80-hour work weeks in factories contributed to excessive darkness.
"But today, too, people are increasingly having a lack of sunlight," says Linseisen. Many workers travel from home to work in their cars, children spend endless hours in front of their computer screens and senior citizens disappear into their nursing homes and seldom get outside. Add to that the skin cancer-phobes, who constantly put on sunscreen with SPF 50 the minute the clouds disappear from the sky.
A Natural Solution
Is the only way out of the dilemma taking vitamins regularly? At least for babies, who are not supposed to be in the sun unprotected, this has long been a recommendation. But what about adults? In the United States, sales of vitamin D tablets have multiplied tenfold since 2001.
The experts taking part in the DGE report prefer a natural solution. Linseisen only advises vitamin D tablets in cases when there is no other choice, such as with many senior citizens. Otherwise, the researcher advises people to "go out in the sun!"
But in moderation. "We strongly advise against treating a vitamin D deficiency with excessive sun exposure or visits to tanning salons," says skin cancer researcher Rüdiger Greinert at the Elbe Hospital in Buxtehude, near Hamburg. "But we dermatologists don't have anything against a short walk during the lunch break."
According to the DGE report, in order to get enough vitamin D, people should expose there hands, arms and face at least three times per week to the sun for between five and 25 minutes, depending on their skin type.
Linseisen says: "When it comes to UV rays, we must find the right balance between the benefits and the damage."