DEPRIVED OF SUNSHINE Most Americans lack vitamin D. Some 99 percent of the vitamin D we make comes from exposure to the sun.
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Three-quarters of U.S. teens and adults are deficient in vitamin D, the so-called "sunshine vitamin" whose deficits are increasingly blamed for everything from cancer and heart disease to diabetes, according to new research.
The trend marks a dramatic increase in the amount of vitamin D deficiency in the U.S., according to findings set to be published tomorrow in the Archives of Internal Medicine. Between 1988 and 1994, 45 percent of 18,883 people (who were examined as part of the federal government's National Health and Nutrition Examination Survey) had 30 nanograms per milliliter or more of vitamin D, the blood level a growing number of doctors consider sufficient for overall health; a decade later, just 23 percent of 13,369 of those surveyed had at least that amount.
The slide was particularly striking among African Americans: just 3 percent of 3,149 blacks sampled in 2004 were found to have the recommended levels compared with 12 percent of 5,362 sampled two decades ago.
"We were anticipating that there would be some decline in overall vitamin D levels, but the magnitude of the decline in a relatively short time period was surprising," says study co-author Adit Ginde, an assistant professor at the University of Colorado Denver School of Medicine. Lack of vitamin D is linked to rickets (soft, weak bones) in children and thinning bones in the elderly, but scientists also believe it may play a role in heart disease, diabetes and cancer.
"We're just starting to scratch the surface of what the health effects of vitamin D are," Ginde tells ScientificAmerican.com. "There's reason to pay attention for sure."
But Mary France Picciano, a senior nutrition scientist in the National Institutes of Health's Office of Dietary Supplements, is skeptical that the dip is as deep or widespread as suggested, noting that there's disagreement on how much vitamin D is needed. She notes that the Institute of Medicine (IOM) defines insufficiency as less than11 nanograms per milliliter. Using that as a threshold, some 10 percent of U.S. adults are vitamin D deficient, according to a study published in November in the American Journal of Clinical Nutrition.
That earlier study, co-authored by Picciano, also found that vitamin D deficiency had become more common between the late 1980s and 2004, but that between half and 75 percent of that difference was due to changes in the test used to measure those blood levels and therefore wasn’t a true gauge. "The results are far overstated and their findings are not as accurate as ours," Picciano says. "There is some deficiency — I don't want to minimize that — but it's not as high as they're saying."
Ginde insists the results are reliable. "There's potential for methodology contributing to some of what we found," he says, but the magnitude of the change and other research "argue that this is the reality in the U.S. right now."
Ginde, who last month linked vitamin D deficiency to catching more colds, blames increasing use of sunscreen and long sleeves following skin cancer-prevention campaigns for the change. Using a sunscreen with as little as a 15-factor protection cuts the skin's vitamin D production by 99 percent, the study notes, and there are few sources of the vitamin in our diets. Some food sources are salmon, tuna, mackerel and vitamin D-fortified dairy products, such as milk.
IOM recommends that people get 200-600 International Units (IU) of vitamin D daily, but it's reviewing whether to increase that recommendation in the wake of new studies. An update is expected in May 2010. Ginde believes that whatever those recommendations turn out to be, blacks should take double the amount of vitamin D supplements, because they have more melanin or pigment in their skin that makes it harder for the body to absorb and use the sun's ultraviolet rays to synthesize vitamin D. He adds that people should also take greater amounts of vitamin D in the winter when there's less sunlight.
Jim Fleet, a professor of foods and nutrition at Purdue University who wasn’t involved in the study, agrees with Picciano that failing to consider differences in the vitamin D testing methods (used during the two survey periods) was "a fatal mistake." But he tells ScientificAmerican.com that real deficiencies in vitamin D exist, even when they're defined by the lower cutoff, and that some 40 percent of African Americans are vitamin D deficient according to that threshold.
"If you look at people in the categories that we worry about," he says, "that’s still a lot of people."
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11 Comments
Add CommentPlease note that intoxication with Lead can be a cause of vitamin D deficit.
Reply | Report Abuse | Link to thisThere are many other benefits of vitamin D apart from fracture prevention. The Canadian Cancer society now recommends that everyone take vitamin D to prevent cancer. If you go to www.vitaminD3world.com you can see the data that led to this recommendation
Reply | Report Abuse | Link to thisVery informative article, but I am still confused as to HOW much vitamin D is needed. I love my 32-year-old husband to skin cancer, thus making it my life mission to help raise awareness about the need for better sun protection. I get asked the question about Vitamin D every so often and it has always been my understanding that the amount needed for the suggested daily levels can be derived from 10-15 minutes in the sun each day or adding a couple helpings of vitamin-D rich food to your diet each week (i.e., broccoli, vitD milk, etc.) Am I wrong on this? Thanks for the input. Rhonda Sparks (www.uvskinz.com)
Reply | Report Abuse | Link to thisOops... just re-read my post... although I 'loved' my husband, I meant to write I 'lost' my husband to skin cancer. Sorry about the typo! Rhonda (www.uvskinz.com)
Reply | Report Abuse | Link to thisRhonda - Sorry to ehar about your husband. You want to have a blood level between 50 and 60 nanograms per millilier (ng/mL) as measured by a 25(OH)D blood test. For most people this means 5000 to 7000 IU per day, or 50,000 IU once a week. If you want to read more, there are several excellent books. Try this one: Vitamin D3 and Solar Power for Optimal Health by Dr. Marc Sorenson, available at www.vitaminDdoc.com. You will read over 50 pages that will rock your world about skin and internal cancer. From looking at your website, I know you advocate covering up to avoid sun contact. Dr. Sorenson is a strong advocate of gentle sun exposure to boost vitamin D levels, being careful to never get sunburn.
Reply | Report Abuse | Link to thisHi,
Reply | Report Abuse | Link to thisI come from an irish family who did not care for the sun !My father died of bowel cancer age 49yrs,followed shortly after one at a time 5 of his brothers died of cancers.His father and siblings also died of cancers.Two of my uncles children have cancers.
My mothers side did not do well either,my mother breast cancer and osteoporosis,her sister and 2 cousins died of MS,my mother mother,aunt and granmother also had osteoporosis,my daughter who is still in her 20's has osteoporosis.I have also been very sick and now have cataracts and a calcified pancreas.My blood test for vit D was in my boots,very deficient.I eat very well,lots of fish ect,milk dairy........so I believe there is something in this vit D problem,I feel a new person since taking it and so does my daughter. I also sunbathe without lotions,they gave me 2 basal cells,I always covered myself in it ! Hope this gives a real persons view and how it affected my family,I also live in the UK and have had poor summers,I now jet off to sunny Spain. From the new tanned healthy lady Ros
Hi,
Reply | Report Abuse | Link to thisI come from an irish family who did not care for the sun !My father died of bowel cancer age 49yrs,followed shortly after one at a time 5 of his brothers died of cancers.His father and siblings also died of cancers.Two of my uncles children have cancers.
My mothers side did not do well either,my mother breast cancer and osteoporosis,her sister and 2 cousins died of MS,my mother mother,aunt and granmother also had osteoporosis,my daughter who is still in her 20's has osteoporosis.I have also been very sick and now have cataracts and a calcified pancreas.My blood test for vit D was in my boots,very deficient.I eat very well,lots of fish ect,milk dairy........so I believe there is something in this vit D problem,I feel a new person since taking it and so does my daughter. I also sunbathe without lotions,they gave me 2 basal cells,I always covered myself in it ! Hope this gives a real persons view and how it affected my family,I also live in the UK and have had poor summers,I now jet off to sunny Spain. From the new tanned healthy lady Ros
What Picciano doesn't state is that she is referring to current guidelines for Vitamin D which were established years ago to simply ward off rickets. Every Vitamin D expert agrees that blood levels need to be between 50-80 ng/ml. The government is not listening to the experts and their cries to raise the recommended daily allowance for Vitamin D. The onl yproblem I foresee is that every person's daily allowance is different. There are way too many variables to consider when simply trying to tell someone they need a specific amount if IU of Vitamin D. THe alternative is to get your Vitmain D the natural way and to use the sun as it was intended. Your body knows exactly how much Vitmain D it needs and has a natural regulator to allow for the proper amount to be processed. When you can't process Vitamin D outside becuase of geography (Vitamin D Winter) go to the tanning salon and get a responsible amount of controlled UVB. Some say your body can produce 1000 IU of Vitamin D per minute from fullbody sunbed exposure. Just afew minutes a couple times a week will do!!! don't over do it.
Reply | Report Abuse | Link to thisWhere did the money come from to fund the studies? the reason for my question is that formula companies want the data to reflect a lack of Vit D in breastfed infants, therefore formula is a prefered method of feeding or supplementing. This is a prime example of undermining a person's confidence in doing the right thing for the baby.
Reply | Report Abuse | Link to thisThe other side to the Vitamin D story at http://www.diabeticconnect.com/news-articles/5721-the-vitamin-d-scam
Reply | Report Abuse | Link to thisI think this information about vitamin D is a wake up call about the lack of information, in general, about vitamin deficiencies, vitamin supplements and our diet. Further [unbiased] research definitely needs to be done. I did a little research myself about vitamin supplements and found some interesting information. check out the article here http://akintogreen.com/article/vitamin-supplements-magic-pills-or-placebos
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