Saturday, July 25, 2009


By Robert Bazell, Chief MSNBC Science & Health Correspondent

One of the refrains we hear most often covering the health and science beat is: “You tell me one day something is bad for me and then it is good.” There are many legitimate reasons for this perception, and this story is a fine example.

About three decades ago, dermatologists alarmed at the rising incidence of skin cancer began a campaign to get people to stop spending so much time in the sun, or at least to cover up with strong suntan lotion if they did. The effort was enormously successful. Now there is a big problem with it. When the sun’s rays (unfiltered by lotion) strike our skin, our bodies produce vitamin D. Scientists always knew vitamin D is critical for good health. Children not exposed enough to the sun can get a terrible disease called rickets.

But around 1989 scientists began to discover that vitamin D played an important critical role in all the cells in the body, and they hypothesized that a lack of vitamin D could increase the risks for cancer. Large population studies have now verified that people with low vitamin D levels indeed have higher levels of several common types of cancer, including colon and breast. Some of the best research comes from the Nurse’s Health Study and the Health Professionals Study -- two efforts run by the Harvard School of Public Health that have been following tens of thousands of people for decades. The latest study looks at cancer incidence in men. In addition to the Harvard study, two others have come out demonstrating an increased incidence of breast cancer in women with low levels of vitamin D. Those were presented at the annual meeting of the American Association for Cancer Research.

So how much vitamin D do we need? Based on these latest studies, experts now recommend a minimum of 1,000 units a day. We get about 200 from food and supplements usually contain 400. That is where the sun comes in. No one is saying people should get sunburned or even tan. But you can get 1,000 units of vitamin D by spending 10 minutes in the sun in the middle of the day with your arms and face exposed. Amazingly, with our automobile and indoor lifestyle many Americans do not get even that much. So here is an example where the advice is changing not because of confusion, but because science is making genuine progress.

Once again, science is confirming the age old wisdom that sunlight is essential and beneficial to all living things.

1 comment:

Grammar Gal said...

Fascinating article, mcl! Thank you for bringing this to the attention of residents of Rogers Park, who spend a great deal of spare time at the many beaches we have here, slathering themselves with one sunblocker or another.

What surprised me most was the 'ten-minute factor'.

Let's not forget the most important point: Sunshine is FREE!