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ANAHEIM Although vitamin D insufficiency has reached what might be considered epidemic proportions, it’s failed to move onto the radar screens of most physicians, much less consumers. A host of new studies now link excess weight with a deficiency in this, the sunshine vitamin. But that wouldn’t explain why female soldiers become increasing D-ficient during basic combat training. For them, an Army study suggests, the problem may trace to what they wear.
The findings emerged this week at Experimental Biology 2010. This umbrella conference, sponsored by the American Society of Nutrition and five other biomedical research societies, also hosted the annual meetings of another 17 guest research societies.
Vitamin D isn’t really a “vitamin” in the classic sense — a nutrient that the body uses to build tissue and perform activities. This so-called vitamin is instead the starting ingredient for a hormone: 1,25-dihydroxy vitamin D. That hormone plays a role in everything from building bone and muscle to fighting infection and risk of diabetes — even autoimmune diseases.
Over the millennia, people have evolved the ability to make ample vitamin D in their skin, at least during most of the year. However, covering up with clothes or sunscreen can block the ultraviolet light needed for skin to stimulate its production. Foods can supply some D, but tend to be a rather anemic source. Not surprisingly, many nutritionists now advocate dietary supplements.
Not that many people avail themselves of much supplemental D — as evidenced by a growing number of studies, many of them presented at this week’s meeting. Most of these measured the form of D that circulates in the body: 25-hydroxy vitamin D. And even in regions where UV exposure remains fairly high year round, like Puerto Rico, people don’t seem to be getting nearly enough of the vitamin.
For instance, Karen Gil and her colleagues at the University of Puerto Rico, in San Juan, found that among the 100 overweight and obese men and women they looked at, 55 percent had sufficient vitamin D — and 29 percent were clearly deficient. Not surprising, given the numbers, some 60 percent of the surveyed individuals were not eating the recommended daily allowance of D (which nearly every nutritionist concedes is woefully in need of revision upward), and many didn’t get much time in the sun.
A drink didn’t hurt
Somdat Mahabir of the National Cancer Institute and his colleagues were investigating the role of alcohol on serum vitamin D values among post-menopausal women. Although alcoholics tend to have weak bones, some data had indicated that moderate alcohol consumption might improve bone mineral density. The question Mahabir’s group sought to answer: Would a drink or two a day compromise bone health?
So they recruited 51 postmenopausal women to a long trial. For eight weeks, each got no alcohol (in orange juice), the equivalent of one drink’s worth, or two drink’s worth of alcohol. Each woman went through each eight week cycle, although in a random order (with four weeks off in between each cycle). During the test phases, all meals were prepared for the women — ensuring that each received all the nutrients needed to support health and maintain her current weight.
Bottom line: This federal study found no link between alcohol and D. Only two things stuck out: Blacks tended to have about two-thirds as much 25-hydroxy vitamin D in their blood as did white women (a trend noted elsewhere in the past). And the more obese a woman was, the lower her vitamin D level. Some studies have indicated that anything under 80 nanomoles of 25-hydroxy vitamin D per liter of blood should be deemed insufficient. In this new NCI trial, lean women tended to average about 60 nm/l, overweight women had around 55 nm/l, and those who were obese averaged only about half the desired level — i.e. roughly 40 nm/l.
Slimming down helps . . .
The good news: A year-long Jenny Craig-sponsored study of weight loss in roughly 400 women in their mid-40s found that as these ladies shed the pounds, their vitamin D values climbed. Which was a good thing since their starting (and, unfortunately, ending) vitamin D levels would qualify them as deficient.
Still, women who dropped 10 percent of their body weight increased 25-hydroxy vitamin D values by about 9 percent, reports Cheryl Rock of the University of California, San Diego, and her colleagues. One possible confounder they couldn’t exclude: As women slimmed down, they might have spent more time exercising outdoors — soaking up some rays. And making extra vitamin D.
. . . unless you’re wearing combat fatigues
Presumably, the 74 female Army soldiers undergoing basic combat training at Fort Jackson in Columbia, S.C., between August and October got plenty of sun — and exercise. Still, during eight weeks of intense drills and training, their 25-hydroxy vitamin D dropped by an average of 13 nm/l. Which is bad news, since nearly 60 percent of these young women entered basic training below 75 nm/l. By the end of their training, 75 percent fell into this category.
Drops varied by ethnicity. Blacks started low — about 46 nm/l — and stayed there. Almost exactly. Hispanic whites started out averaging 74 nm/ml and non-Hispanic whites started at nearly 90 nm/l. Vitamin D values in both of these groups dropped 16 percent during training.
Although it’s impossible to know precisely what contributed to the decline in their circulating vitamin D levels, Nancy Andersen of the U.S. Army Research Institute of Environmental Medicine in Natick, Mass., and her colleagues speculate it was the uniforms these women had to wear — and a diet that didn’t provide much vitamin D.
There may be an important lesson here for the military, the authors say. They point out that risk of stress fractures — one of the most debilitating injuries in recruits — has been linked to low vitamin D. “And attrition rate from basic combat training in female soldiers with a diagnosis of stress fracture is 60 percent,” they add.
Want to retain recruits, keep their bones healthy. And what helps a 21-year-old female recruit will help the rest of us as well. We all need to bone up on plenty of D, and the plumper and more darkly skinned among us may need to work especially hard at fighting D-ficiency.
Found in: Biomedicine, Food Science, Humans, Nutrition and Science & Society
- Science & the Public : Vitamin D is a flu fighter
- Vitamin D: Blacks need much more
- Food for Thought : Canadians Advocate Boosting Vitamin D in Pregnancy
- Food for Thought : Breathing Easier with Vitamin D
- Food for Thought : Vitamin D Boosts Calcium Potency
- Food for Thought : Understanding Vitamin D Deficiency
- Vitamin D: What's Enough?
- Vitamin Boost
- The Antibiotic Vitamin
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Gil, K.E., et al. 2010. Low Vitamin D Status Among Overweight and Obese Puerto Rican Adults
FASEB Journal 24(April):917.17. - Mahabir, S. et al. 2010. Effects of Alcohol and Alcohol-Metabolizing SNPs on Serum Vitamin D Levels in Postmenopausal Women in a Controlled Feeding Study. FASEB Journal 24(April):325.7
- Rock, C.L. et al. 2010. Weight Loss is Associated with Increased Serum 25(OH)Vitamin D in Overweight or Obese Women. FASEB Journal 24(April):917.2
- Andersen, N.E., et al. 2010. Changes in Vitamin D Status of Female Soldiers During Basic Combat Training. FASEB Journal 24(April):917.5
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Vitamin D synthesis from UVB exposure is a self limiting process. You don't suffer vitamin D toxicity from sun exposure because further exposure of vitamin D3 to UVA degrades it to supra-sterols the body doesn't use.
So vitamin D3 brought to the surface of the skin by exercise induced sweat will be lost by exposure to UVA and showering.
Athletes, marathon runners, cyclists, skateboarders despite spending hours training in sunshine almost universally have low 25(0H)D status.
The situation is actually worse then stated above as "Circulating 25-Hydroxyvitamin D Levels in Fully Breastfed
Infants on Oral Vitamin D Supplementation" shows, at latitude 32n, it takes 6400iu/daily for lactating mothers to provide Vitamin D replete milk to their babies.
Researchers tend to use 32ng as the cut off point for sufficiency but NATURALLY full body sun exposure from living outdoors near naked achieves 25(OH)D between 60~80ng/ml. It's only around 60ng/ml there is sufficient stored D3 to pass surplus to the next generation.
A further factor involved with athletes and probably young army trainees is the use of sweetened energy drinks like Gatorade as it's known HFCS induces 25(OH)D insufficiency.
200ng/ml above which toxicity has been recorded = 500nmol/l
100ng/ml typical level achieve living naked outdoors end of summer = 250nmol/l thought to be ideal for those with a cancer diagnosis.
80ng/ml top of the normal natural desirable range 200nmol/l
60ng/ml the natural level providing a good reserve of stored D3 to power immune function and suplly D3 replete breast milk = 150nmol/l
55ng/ml level above which less chronic illness is found = 137.5nmol/l
50ng/ml body starts to build a reserve store of D3 125nmol
42ng/ml at this level all Caucasians can achieve optimum Bone mineral density and ideal calcium uptake occurs generally this levels assures basic daily vitamin D3 needs are met but NO STORED D3 reserves available = 105nmol/l
32ng/ml level at which average Caucasian optimizes BMD =80nmol/l and health professionals think is sufficient.
There is a reluctance on the part of health professionals to recommend an intake of Vitamin D3 that effectively reduces chronic disease incidence.
Nutritionists and industry researchers have created an artificial 'deficiency' by declaring 60 or more should be normal -- what rubbish and poor science.
And congrats to the PopSci author for actually pointing out that it is 1,25-dihydroxy vitamin D that is the ultimate end result.
That is the important value to be looking at not 25,D.
If your 1,25D levels are BELOW 40 pg/ml then you are OK -- if into the 40s then you may have systemic infection issues.
Who has high 1,25D values? People with CFS, Lyme, MS, Diabetics, Lupus, Autism, Sacroidosis and all kinds of other chronic illnesses.
Very often they all have low Vit D levels that will accompany the higher 1,25-dihydroxy vitamin D.
Researchers would rather just measure 25,D levels since it costs about 5-10 times less than a 1,25D test which are much trickier to prepare and do.
Plus they wouldn't know what to make of the high 1,25D values anyways which is an effect of disease -- not a cause. Raising Vit D levels certainly won't help.
So if you really want to go in the right direction then spend the extra money and test for 1,25D as well.
You would think the researchers would have gotten a clue on that by now.
One issue not yet explored in the literature is metabolic clearance.
How much D did these women use up due to their physical training?
As Ted points out, the issue of surface production, an old study by Holmes (on our website) shows that soap and even water removes some D.
I think the issue of metabolic clearance will be one of the next very important discoveries about D. I predict it will be increased by both exercise and illness. That is a healthy sedentary person will need less than someone with diabetes who is exercising regularly.
John Cannell, MD
The Vitamin D Council
It’s a natural mistake, a conflation of nmoles/L with ng/mL (i.e. nanomoles per liter vs. nanograms per milliliter).
Two thoughts for future work on D.
First: As a teacher, I deduce that the Achievement Gap might be nothing more than a vitamin D gap, and that the epidemics in children of allergies, ADD, asthma, obesity, diabetes, and even hypertension would all drop if kids got enough D. See more at GoodSchoolFood (dot) org (upper left corner).
Second: children today are also low in the essential omega-3 fatty acids DHA and EPA. It’s no coincidence that fish is the best food source for both D and DHA-EPA—and that we eat far less fish now than in past decades. The tidal wave of fatty acid research shows a lot of overlap in how these nutrients benefit people -- both protect from diabetes, immune disorders, allergies, asthma, hypertension, mental illness, and obesity, which are all epidemic among our youth. And even as vitamin D protects against stroke, heart disease, and cancer, so do DHA and EPA.
Another similarity is that the FDA has stalled in setting better standards for both D and the omega-3s. Our current high cost of health care will be many times worse as each wave of malnourished children reach adulthood.
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