The story actually started around 60,000 years ago, when humans first migrated away from the Tropics and their strong sunlight. Immediately we developed medical problems, which were remediated through natural selection by lightening our skin, since dark skin color – melanin – is a sunblock.
UV intensity declines dramatically with reduced sun angle, and those living at higher latitudes receive as little as ten percent of the UV experienced near the Equator. The results were swift. People migrating north soon developed vitamin D deficiencies and were removed from the breeding pool in a cruel Darwinian process: The fetus in women with rickets (a Vitamin D-deficiency condition) is unable to emerge from her body, and both die in childbirth.
Within just a few thousand years, natural selection had turned some people’s skin white, so they were able to manufacture ample vitamin D even from the reduced Sun-intensity of higher latitudes. And they did indeed get enough of it – at first. In Germany and the US, much of the year is warm enough so that the original Native American or Germanic tribes wore very little clothing. Skin was almost fully exposed for over half the year, and the body stores Vitamin D in muscle and fat.
But starting a century ago, everything changed. First, America went from a mostly outdoors agrarian society to a mostly indoors manufacturing one. Then, when air conditioning became widely available in the 1960s, people stopped keeping their windows open – and glass blocks UV.
The last straw was sunblock. It did not even exist until 30 years ago. Moreover, people were advised to cover themselves with these lotions as a way to prevent skin cancer. The metamorphosis was complete. We had become like the Morlocks in the H. G. Wells’s book The Time Machine, shielded from sunlight.
Dr. John Cannel, a researcher at the nonprofit Vitamin D Council, told me last year that “We are the first society of cave people. Nature never dreamed that we’d deliberately avoid the Sun so thoroughly. [And therefore] our blood’s vitamin D levels are just a tiny fraction of what they were a century ago.”
That vitamin D is super-important is no longer in doubt. It is recommended increasingly by family doctors and the popular media alike. Last year, Reader’s Digest called vitamins in general “a scam” and urged people to take no daily supplements whatsoever – with the single exception of vitamin D3.
A spate of studies strongly indicate that vitamin D is the most powerful anti-cancer agent ever known. Spending just ten minutes in strong sunlight – the kind you get from 11 a.m. to 3 p.m. – will allow your body to make as much vitamin D as drinking 200 glasses of milk. Why does Nature do this so quickly? The implied answer is that we were designed to have a high and steady level of this vitamin in our bodies.
Dr. Robert Heaney of Creighton University, who has treated thousands of patients with vitamin D, points to 32 randomized trials in which the majority were strongly positive. For example, a big study of women whose average age was 62 who were given a large daily vitamin D supplement enjoyed a whopping 60 percent reduction in all kinds of cancers after just four years, compared to a control group.
Last November, the National Academy of Sciences issued its first new recommendations about the vitamin since 1997 – and they disappointed many people. The Academy did boost its suggested daily amounts to 600 units for most adults. Yet, Dr. Cannell and many other researchers say even these boosted amounts are still “irrelevant dosages” and urge at least 3,000 units daily.
Of course, you should never let yourself burn, especially if you have fair skin. But it might be wise to get more sun. The nearest star could save your life.
@ Bob Berman
Parts of this article were excerpted from The Sun’s Heartbeat – and Other Stories from the Life of the Star That Powers Our Planet by Bob Berman, published next month by Little, Brown.
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