Sunshine is just what the doctor ordered

Vitamin D is being hailed by scientists as having more power to cure respiratory illnesses than the once-favoured vitamin C.

Ten minutes in the sun can far surpass the amount of vitamin D one could get from food, scientists say.

DENVER // Forget the apple a day, or that glass of orange juice in the morning. A daily dose of sunshine may do more to keep the doctor away. And you might want to toss out your multi-vitamin tablets, too. A rash of new studies on vitamins and supplements is raising questions about long-held medical dogma for staying healthy - although scientists and doctors alike admit they are a long way from having a complete picture.

A study published last week in Denver found that vitamin D, most commonly absorbed by the body through exposure to sunlight, appears to be a more powerful antidote to respiratory illnesses than vitamin C, long embraced as a critical foot soldier in the fight against the common cold. And a separate major analysis on older women by the Fred Hutchinson Cancer Research Center in Seattle, Washington, has concluded that taking a daily multi-vitamin does not lower the risk of cancer nor extend life expectancy.

US residents swallow US$23 billion (Dh84bn) worth of vitamins and supplements annually. Almost half of all adults here take at least one daily pill to supplement their diet, as do one third of all children. Many gobble up "mega-doses" of vitamins and supplements, believing they will lengthen their lifespan, improve their skin and bones and reduce illness. More and more studies are suggesting, however, that vitamins - although critical to good health and nutrition - are still far from understood, and may not be best absorbed by the body in pill form.

Last year, a decade-long study on 15,000 male doctors dashed hopes that taking vitamins E and C could reduce rates of heart disease and cancer. A separate finding concluded that vitamin E also played no role in reducing prostate cancer. "Scientific data is lacking on the long-term health benefits of supplements," said Marian Neuhouser, the lead author of the Hutchinson Center study. Take vitamin C, for example. For decades, US parents fed their children orange juice and vitamin C tablets, while some doctors prescribed high doses of the vitamin to patients with respiratory illness.

However, Adit Ginde, the lead author of the University of Colorado study, said: "There's little scientific evidence to support the effectiveness of vitamin C against respiratory problems." Rather, it is vitamin D that appears to regulate the immune system, he said. People with vitamin D deficiency - which increases in cold winter months when there are fewer sunlight hours and people spend less time outdoors - may need to supplement their diets with food rich in the vitamin such as milk, salmon, tuna and eggs, or take it in the pill form.

People with darker skin tones will develop the deficiency faster than lighter-skinned people, he added. Perhaps more controversially, there is clear evidence that the easiest way to soak up the benefits of vitamin D might be some time in the outdoor lounge chair. "Ten minutes in the sun with your sleeves rolled up would far surpass your intake of vitamin D than what you could reasonably consume through food," Dr Ginde said.

His advice counters what skin doctors have been telling the US public for decades: that exposure to the sun causes wrinkles and can lead to skin cancer. Dr Ginde agrees that people need to carefully regulate the time they spend in the sun without the use of sunscreen or protective clothing. "Everything has to be weighed against the risks, like not getting a sunburn," he said. "But there may be other benefits to sunlight that we still do not know about."

Similarly, some scientists studying vitamins have come to suspect that good nutrition comes from the entire package that healthy foods offer, but extracting specific vitamins in pill form may not be as effective. For example, the body may need the fibre in a spinach leaf, for example, to properly absorb its iron, folic acid and other nutrients. "There is a lot more that we still need to learn," admitted Daniel Fabricant, a vice president at the Natural Products Association, a lobbying group for the vitamin industry.

However, Dr Fabricant and other proponents of supplement use dispute some of the recent findings, especially the Hutchinson study, saying women in that trial did not all take the same multi-vitamin, making it impossible to know what levels of various nutrients each was ingesting. Meanwhile, other factors contributing to their health, including exercise and diet, were not factored into the results.

Gene Arnold, who runs a vitamin shop in Malibu, California, that is popular with movie stars, said his decades of experience blending vitamin drinks has him convinced that it is a terrible idea to suggest Americans not supplement their diets. "These studies often don't take into account the participants' complete health picture," he said. "I just don't follow how they come to these conclusions." [e-mail]