Interview With the Vitamin D Guru

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We don’t get much sunshine up here in the Great Northwest. And few sunny days mean many of us are deficient in Vitamin D. In fact, Vitamin D deficiency is remarkably common even for those living in sunnier climes. Most Seattleites are unaware that we have a Vitamin D expert right in our own backyard. Craig A. Keebler, MD holds board certifications in obstetrics, gynecology and bariatric medicine. His book, Know Your D, sets out to teach us about this essential nutrient. Zing: To those who are new to the Vitamin D topic, how would you describe Vitamin D in a nutshell? Dr. Keebler: Actually, Vitamin D is not a typical vitamin. It’s a gene regulator. Vitamin D activates nearly 1000 genes necessary for good health. For example, it activates at least 60 genes to prevent or defeat cancer cells. It regulates over 12 genes that support the immune system. Vitamin D influences genes that regulate insulin production and effectiveness. It has an effect on genes that decrease inflammation and prevent autoimmunity. Even reproductive health depends on Vitamin D. Zing: What got you interested in Vitamin D? Dr. Keebler: I was working at the time in my medically supervised weight loss clinic. I knew about Vitamin D but it was not a focus of my practice. I was asked by a Rheumatology nurse practitioner if I knew my own Vitamin D level. I was shocked to find out my level was low despite it being summertime. I then learned that people who are obese have a harder time achieving healthy blood levels. Of course, people with obesity also face increased risk of inflammatory conditions and blood sugar problems. So Vitamin D grew to become an important consideration as I took care of these patients. Zing: Why are so many of us deficient? Dr. Keebler: It’s a consequence of modern life. For most of human history: 90% of our Vitamin D was produced from UV light hitting exposed skin. Now, we are outside less as a society (less work, play and exercise happen outside). Even when we are outside, we lather on sunscreen more than ever before. Now, it’s appropriate to use sunscreen, but since it prevents Vitamin D production it’s important to use a Vitamin D supplement. Zing: What did you find most surprising as you began to research Vitamin D? Dr. Keebler: Every month, one can find a whole new area of Vitamin D investigation. We are finding so many areas of health and disease that are affected. Take Vitamin D and brain health. Animal studies are showing us that offspring born to mothers with decreased Vitamin D have more mood disorders, more learning impairments, focus and social problems. Bottom line: the brain is very dependent on Vitamin D. Zing: Any clinical success stories involving Vitamin D? Dr. Keebler: Here’s an observation that struck me: After improving their Vitamin D to healthy levels, my patients would tell me “This is the first winter that I’ve lived in Seattle that I didn’t have the blues.” This goes back to Vitamin D’s influence on brain health. Zing: What precautions should people be aware of? Dr. Keebler: Ideally, people should work with a healthcare practitioner who can check your blood level and custom tailor a dose to fit your specific needs. Regular checks (minimum once a year; more often if you have a specific health concern) will prevent the possibility of getting too much. By the way, there are no recent reports of toxicity (meaning overdose). Past reports of Vitamin D blood toxicity involved people taking 100,000+ units per day. (The common adult maintenance dose is less than 10,000 units per day.) The big problem of our time is not the threat of overdose, its inadequate supply. Zing: What do you think is the next frontier in Vitamin D research? Zing: Back to those who are Vitamin D newcomers. What key takeaway should they remember about Vitamin D? Dr. Keebler: How about three things:
  1. Assume you are Vitamin D deficient until proven otherwise! 40ng/ml is a blood level where many health benefits are noticed. Speaking of testing, the best blood test is called “25-Hydroxy-Vitamin D” (sometimes abbreviated 25-OH Vitamin D).
  2. It’s easier and safer to achieve healthy levels via supplementation than it is to rely on sun exposure.
  3. There are very few food sources that can give an adequate daily supply. But for those who are really interested, 10 cans of sardines will do it!
Learn more about Vitamin D and Dr. Keebler’s book at