COVID-19 Response

What you need to know about testing and the new Safer Badgers app. For more information visit

During this time, please contact us at

Twenty-five thousand years, our Paleolithic ancestors got plenty of sun. Scantily draped in animal hides, they spent their days roaming outdoors, hunting and gathering food. With so much sun exposure, they made a lot of vitamin D, the “sun vitamin,” through their skin—around 10,000 units per day, biologists estimate.

Today, with lifestyles that keep us indoors and in vehicles, we don’t get out in the sun nearly as much. And when we do, we often slather ourselves in sunscreen to avoid skin cancer—a protective measure that unfortunately also blocks production of vitamin D. Although we get vitamin D from our food, primarily through fatty fish and fortified milk, yogurt and cereal, there’s been growing concern over the past decade that we aren’t getting enough, and that we may be missing out on a number of the vitamin’s health benefits that we’re just starting to understand.

And if newspaper headlines are to be believed, we could be missing quite a lot. Week after week, articles are published touting vitamin D’s protective role in a wide range of diseases and ailments—cardiovascular disease, hypertension, cancers of the colon, breast and prostate, cold and flu, asthma, autism, depression, osteoporosis, arthritis, neurodegenerative disease, multiple sclerosis, type I diabetes—and even longevity. But don’t count on all of these studies panning out, warns CALS biochemist Hector DeLuca. DeLuca should know—he’s a globally recognized authority on vitamin D whose six decades of research laid the groundwork for much of what we know and are discovering about it today.

“I’m really worried about how much attention vitamin D has received lately because we did this with vitamin E many years ago—where vitamin E was going to cure all kinds of things and of course it didn’t—and it’s completely off the radar screen now,” DeLuca says. “I don’t want that to happen to vitamin D because there are many places where it’s really effective.”

So what are vitamin D’s health benefits, and what do we need to do to maximize them? Both are huge questions in the scientific and medical fields. At this point, only one thing is certain: vitamin D is essential for strong bones. Beyond that, the jury is out because we don’t have the large, randomized human clinical trials required to make those calls—yet.

Nevertheless, there have been a significant number of promising in vitro and animal studies over the years, enough to convince many vitamin D researchers to increase their own doses. And when the U.S. Institute of Medicine in 2010 raised the Recommended Dietary Allowance for vitamin D from 400 to 600 units per day for adults—taking into consideration only the vitamin’s impact on bone health—it didn’t sit well with many members of the vitamin D research community who think the recommended intake should be considerably higher.

“Many people thought that was absolutely absurd—that people should actually be taking anywhere from 2,000 to 4,000 units a day,” says Wes Pike, another CALS vitamin D researcher who is internationally respected for his work. “But the committee didn’t take any risks. They discounted all the other things that people believe higher amounts of vitamin D could be beneficial for—muscle function, a healthy immune system, combating cancer and so much more. And some of those things are real, it’s just that there’s no strong clinical evidence for them yet.”

Fortunately, there soon will be a lot more solid evidence about vitamin D’s health impacts—on heart disease, stroke, cancer and more—thanks to a large clinical trial that’s gearing up at the Institute of Medicine’s request. As scientists, doctors and the public wait for answers, CALS researchers are working in parallel, leading an equally important effort to shine a light on vitamin D’s mode of action inside the body and to explore and understand new vitamin D-based treatments for disease—as they have for almost a century.

The story of vitamin D is largely a CALS story. It was identified by biochemist Elmer McCollum, who discovered vitamins A and B as a young faculty member at CALS before joining Johns Hopkins University, where in 1921 he found a substance that cured the bone-softening disease rickets—and named it vitamin D, as it was then the fourth vitamin known to science. In 1923 CALS biochemist Harry Steenbock figured out how to biofortify food with vitamin D by exposing it to ultraviolet light, a discovery that led to the almost complete eradication of rickets by the mid-1940s.

As his last graduate student, Steenbock in 1951 brought on Hector DeLuca, a promising young chemist from the University of Colorado. At Steenbock’s request, DeLuca stayed on to run his lab. “Steenbock was nearing retirement and wasn’t physically well, so he asked if I would stay after my Ph.D. and direct the research in his lab,” says DeLuca. The offer turned into a faculty position in 1959.

“At the time there was a lot we didn’t know about vitamin D and how it makes better bones,” says DeLuca. “I thought, ‘Why don’t we try to figure out how it works, and maybe we’ll learn how certain diseases take place?’ That was my motivation.”

The rest of this story, which was originally published in the Fall 2012 issue of Grow magazine, is available on the Grow website.