Interviewer: With Dr. James Dowd, author of the "Vitamin D Cure" today. Doctor, in your book you say that more than half of Americans are vitamin D deficient. Why is that?
Dr. James Dowd: It has to do with a culture change. If you just go back maybe 50 years. This is before the cell phone, before the personal computer, before flat screen TVs, before cable TV.
Interviewer: People survived then actually.
Dr. Dowd: That's right. We actually were alive back then and breathing. We had dial up telephone, three network television stations, and that was it. For entertainment, you had to get up off your backside and do something. There was less that was automated, mechanized and everything. Just routine daily chores and things required more physical activity, particularly outside. Fifty years ago, they had probably just come out with some of these lawn mowers that were motorized. I remember my dad when I was child, had a push mower that was just those blades. Those things are heavy. It was a lot more work to even mow the yard.
Interviewer: It wasn't self-propelled.
Dr. Dowd: Right. Exactly. No self-propelled mowers, no motorized blades. It was just you grunting, pushing. There was a lot more physical activity. There was a lot more sun exposure. Fifty years ago, how many McDonald's was there? I remember when I was a kid if a McDonald's came to down it was like, oh my God! We've moved into a new era. I remember when I was a child in the late '60s, probably mid '70s, and Doritos were invented. I thought, "Oh my god, it's like manna from heaven. Where did this wonderful thing come from?"
Things have changed dramatically. We don't see that it's changed. We look back maybe five, ten years ago, and, "Nah, it's always been this way."
It hasn't been this way. It was very different. All of those things have impacted our health. We're much less physically active. Physical activity according to the CDC is tied directly to vitamin D levels so when we're sedentary, vitamin D gets stuck in our fat stores, and doesn't get out.
When we don't get out in the sun, we don't make vitamin D, because the ultraviolet B radiation, which is really only available in the spring, summer, and early fall in most of the country, is the only kind of sunlight that makes vitamin D. If we're stuck inside playing video games or Xbox or whatever they are called now, because now the video games are responding to your movement, which is actually a pleasant development that actually you have to move to make your video game work more than your thumbs.
It's still not as much physical activity as it used to be riding your bike to the movie theater, riding your bike two miles away to go see a friend. This was intense physical activity. Our kids are not getting that. They're not getting outside either at the right time to make vitamin D. Our lifestyle has changed dramatically, and even adults, where most of our entertainment, most of our work is indoors now. It's much less physically active.
Interviewer: You mentioned more than half are deficient. Are there certain groups or groups of people that are more at risk than others of being deficient?
Dr Dowd: Yes. There are some high-risk groups. On the website for the book, www.thevitaminDcure.com, there's a risk profile. It's also in the book. The risk profile scores points, more points for these high-risk features. High-risk groups are people who have darker skin tone. That's a particularly high-risk group so African Americans, 90+ percent of them are vitamin D deficient. 75 percent of Latinos are vitamin D deficient, where as only 50 to 60 percent of Caucasians or European Americans are vitamin D deficient. Skin tone is very important as a risk factor.
Because melanin in your skin is actually a sunscreen, and so you need more exposure to get past this screen. Obesity. When your body mass index goes over 30, which is the CDC definition using body mass index of obesity, your risk for vitamin D deficiency climbs more rapidly. Obesity is a significant risk factor.
Actually, just being female is a risk factor. Women have slightly more
vitamin D deficiency, particularly among European Americans. Once your skin is as dark as African American, pretty much everybody is deficient. It doesn't matter. That's such an overwhelming risk factor that it washes out a lot of other risk factors. Among European Americans, vitamin D deficiency is more prevalent in women than it is in men.
The final category that's probably really high risk is breastfed infants.
Breast milk, because the mothers are deficient already, breast milk has little or no vitamin D in it, and certainly not enough to have any impact on the vitamin D of the breastfed infant. The American Academy of Pediatrics has recommended that all breast fed infants be fortified with vitamin D. I think they just raised it to 400 units.
You need vitamin D in these high-risk situations, and you pretty much need to supplement it to get it in the context of our current sedentary indoor lifestyle.
Interviewer: You talk about the darker the skin, the better chance of being deficient. What about the other end of the spectrum when people that are very fair skinned that really can't spend a lot of time in the sun? One would think that they would be deficient as well, but that's not the case?
Dr. Dowd: On the other end of the spectrum with fair skin, it's a double-edged sword. Number one yes, they will make more vitamin D with less exposure to the sun at the right time of the year, and probably even with less skin exposed to the sun. But they also burn much more quickly, which may put them at higher risk for skin cancer. There's that dilemma. I never discourage patients from getting sun, because the amount of sun that we need, there's actually a reasonable safety window there.
Michael Hallick has done a lot of this research, and the skin exposure units are referred to as minimal erythemal dose. One MED, minimal erythemal dose, is the amount of sun exposure that produces just a very faint pinkness of the skin.
Most of the studies show that at 25 percent, one MED, so one-quarter of that sun exposure, produces a ton of vitamin D, which means you could get four times that exposure before you turn a little pink. Turn a little pink is the break point where you say OK, from this point on I'm getting sunburn, below which I'm not.
There actually is a fairly broad window of safety, but with our use of sunscreen today, we're defaulting to zero. If applied appropriately, SPF8 will block 95 percent of vitamin D production. An SPF15 will block close to 98 percent of vitamin D production. When we take our children, one of the more vulnerable groups of people, as far as need for vitamin D goes, and we slather them up with sunscreen, and send them outside, they get no vitamin D.
This is another one of our cultural changes. Fifty years ago there was no sunscreen either. Regular, small exposures to sun will build up a bit of a tan, which is our protection. It is a safe way of getting regular sun exposure. We tend to be sort of the weekend athletes or the weekend yard people, and what we do is indoors, behind a desk, and a computer, six and a half days, half a day on a Saturday or Sunday baking in the sun, and of course, you haven't built up any melanin so you get burned every time you go out.
This is probably the best explanation for why we're seeing a rise in skin cancer. I just don't think that there's an epidemic of people going to tanning salons. I think it's the way we're getting sun exposure has changed as part of our culture, and we're now getting it in big doses, very infrequently, rather than modest doses on a regular basis. Certainly, modest doses on a regular basis is much safer.
Interviewer: You mention women are at a higher risk too. Why is that?
Dr. Dowd: Women are probably at higher risk for a couple of reasons. Number one, they have a higher percent body fat. We know that vitamin D has this proclivity for--it's a fat-soluble vitamin, and like attracts like. It tends to be stored in fat cells until you mobilize it. The way you mobilize it is you exercise and burn the fat. That's how you mobilize it.
Women have a higher percent body fat so their vitamin D tends to stay in fat rather than in the bloodstream where it's going to be measured. Their level tends to be a little bit lower.
Historically, we've also always thought women's jobs as being less
physically active and indoors more often than outdoors. Those variables may also explain why women's vitamin D levels are lower. That has changed somewhat, but in general, all of our jobs are indoors now so it hasn't changed for the better. It's just that men's vitamin D levels are probably dropping because we're all moving indoors too as our economy becomes more of a service economy rather than a labor intensive economy.
Interviewer: How abut geography? What role does that play in vitamin D deficiency and where we live?
Dr. Dowd: Geography played a larger role when we were outdoors with our work and our lifestyles than now that we're indoors. The indoor nature of our current culture has sort of neutralized the effect of geography, but there is a clear difference in geography. There are some interesting graphicals I put in the book, and I stumbled across this. They're on the national oceanic and atmospheric administration website. This is all your hard earned tax dollars to work for the federal government.
They publish these nice UV index charts that are seasonal so that you can see it start in January and rise and peak in July, and then go back down. You can look at that and it tells you. Then there is on the Y-axis the UV index. If your UV index is above three, you can start to make vitamin D. The higher above a UV index of three, the faster you're making vitamin D.
What's interesting is I gave a talk in Anchorage, Alaska, and they have maybe six weeks that their UV index is above three to make any vitamin D. Then you can go look at the UV index data for Hawaii. It's above five or six UV index year round. At peak, in the middle of June it's like 13. You are really cranking out the vitamin D.
With that in mind, you can go on the National Library of Medicine, and there are a handful of case reports from the University of Hawaii or other of people in Hawaii with vitamin D deficiency, because they never get outside. The sun can be there, and it's there during certain times of the year, and you can use tables that are readily available on the web, or you can use the Weather Channel will tell you what the UV index is right now on this day by just logging on and checking the UV index. That will give you an idea. Can I make vitamin D today or can I not make vitamin D today?
The problem with our lifestyles and how much we get outside, and our use of sunscreen, all of these things tell us that most of us probably need to be supplementing vitamin D, because there are just too many obstacles in our way of getting enough sunshine to make enough vitamin D.
Interviewer: We could all move to Florida, but if we don't go outside, it doesn't matter?
Dr. Dowd: That's right. Some of my patients have asked for that
Interviewer: Thank you.
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More than half of the people in this country are deficient in Vitamin D. Dr. James Dowd explains why that is as well as what groups of people are at a particularly higher risk of being deficient
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