The surge in popularity of vitamin D has largely been prompted by the growing number of doctors recommending patients get their blood levels checked, and then prescribing supplements if results fall below 30 ng/mL. In response, the Food and Nutritional Board (FNB) was commissioned to review the current body of vitamin D research. Results were available last week.
The once under-promoted “sunshine vitamin” has been thrust into the spotlight in the last few years, prompting the need for further studies to establish more precise dosing guidelines.
"I think the confusion is understandable," says Patsy Brannon, a professor of nutritional sciences at Cornell University and member of the panel who presented the new RDA. "The committee is very concerned about the lack of evidence-based consensus guidelines for interpreting blood levels for vitamin D. We strongly recommend that these be developed."
Vitamin D Dosing Stirs Debate
The FNB released the results of their review which included recommending an increase in the the vitamin D RDA from 400 IU (international units) to 600 IU for infants through adults age 70, and 800 IUs after age 71. The panel also raised the acceptable upper limit of daily intake to 4,000 IUs for adults, from 2,000.
The panel concluded that for 97% of the population, a blood level of 20 ng/ml of vitamin D is sufficient, a standard vitamin D advocates say is far too low to prevent bone loss or a host of other health issues research has found are associated with a lower levels of vitamin D.
Several major medical groups, including the Endocrine Society and the International Osteoporsis Foundation, concluded that a level of 30 ng/ml is necessary for optimal bone health, while Dr. John Cannell, Executive Director of the Vitamin D Council, goes a step further, recommending D levels for adults and children stay between 50–80 ng/ml all year round.
The 14-member FNB committee was called by the Institute of Medicine,(IOM) an independent nonprofit scientific body, at the request of the United States and Canadian governments. Asked to review the available data on D, the panel looked at nearly 1,000 publications to determine how much vitamin D and calcium people were getting, how much was needed for optimal health and how much was too much.
Critics of the new recommendations say however, that to suggest an adult needs only the same amount of vitamin D as an infant is preposterous and not in the public’s best interest.
As a result, the new vitamin D guidelines have stirred a debate among doctors and scientists, between those who feel the guidelines are adequate and those who feel they're too low for most individuals, in particular for pregnant and lactating women who if D deficient, can negatively affect their infants' health.
Studies have shown an association between low D in pregnant and lactating women, and their children being at higher risk for bone mineral diseases such as rickets and other pathologies such as type 1 diabetes and neurological disorders, even autism.
Vitamin D a Hormone, Vital to Body Processes - Council Recommends Higher Dosing
The buzz over vitamin D partially stems from its unique role in the body. Technically not a vitamin, D is a secosteroid hormone, and unlike vitamins, hormones are the keys to unlocking binding sites on the human genome, the genetic content in an organism. The human genome contains more than 2,700 binding sites for calcitriol; the metabolic product of vitamin D. Those binding sites are near genes involved in virtually every known major disease of humans.
Vitamin D deficiency has been associated, writes Dr. Cannell on the Council's website, "in the pathology of at least 17 varieties of cancer as well as heart disease, stroke, hypertension, autoimmune diseases, diabetes, depression, chronic pain, osteoarthritis, osteoporosis, muscle weakness, muscle wasting, birth defects, periodontal disease, and more."
Exact dosing of D depends on a number of factors, including weight, color of skin (darker skinned people tend to have lower levels), illness etc. Caucasian skin makes 10,000 IU of vitamin D after 20 to 30 minutes of exposure to summer sun.
Dr. Cannell recommends healthy adults and adolescents who avoid sunlight exposure supplement with at least 5,000 IU of vitamin D daily, children under the age of one 1,000 IU vitamin per day and children over the age of one 1,000 IU per day for every 25 pounds of body weight. These levels are drastically higher than the new revised RDA of only 600 IU/day.
Food and Nutrition Board Says High D Not Necessary
The FNB says the high amount of D often recommended by doctors and testing laboratories is unnecessary and could be harmful. They also concluded that calcium supplements aren’t necessary stating in their report that most people have adequate amounts of calcium and vitamin D in their blood supplied by their diets or natural sources of D from sunshine.
"The evidence for [D] for bone health is compelling, consistent and gives strong evidence of cause and effect," says Dr. Brannon. "Yet for the other health issues, she said, "there are relatively few randomized controlled trials, and even in the observational studies, the effects are inconsistent." (Beck, Melinda, November 10th, 30th. “Triple That Vitamin D Intake, Panel Prescribes,” Wall Street Journal. Retrieved December 6th 2010).
The panel was concerned about what they called "emerging evidence of concern" about possible ill effects of too much vitamin D. Dr. Brannon said the panel had seen higher death rates from pancreatic cancer, prostate cancer and other causes in men whose blood levels were above 50 ng/ml. The link is still tentative and may never be proven, she noted: "The difficulty is, you can't design a trial to look at adverse effects."
Vitamin D Advocates Highly Critical of Food and Nutrition Board Report
Critics of the revised RDA for vitamin D say the numbers don’t come close to the required amount people need to assist in the prevention of a long list of health conditions associated with a D deficiency.
Dr. Cannell feels the FNB is publicizing misinformation and that the panel's messaging will make people unnecessarily fearful of overdosing, something he says is extremely rare, particularly with cholecalciferol, referred to as D3. D3 is the naturally occurring form of vitamin D that is made in large quantities when sunlight strikes bare skin; it can also be taken as a supplement.
In a response to the revised guidelines, Dr. Cannell issued a response on the Council's website, (“Today, the FNB has failed millions, November 30th, 2010) pointing out that:
- The FNB said toxicity might occur at an intake of 10,000 IU/day but they couldn’t produce any evidence except one poorly conducted D study indicating 20,000IU/day could cause mild elevation of calcium.
- The FNB only focused on bone health as they did 14 years prior, ignoring thousands of studies from the last ten years that indicated higher doses of D helps heart, brain, breast, prostate, pancreatic, muscle, nerve, eye, immune, colon, liver, mood, skin and most notably, fetal health.
- The panel reasoned that if so many pregnant women have low D then it must be okay because low levels are so common in pregnant women, yet writes Cannell, this is flawed, circular logic.
- It is nearly impossible to raise vitamin D levels with an RDA of only 600 IU/day. 5000 IU/day is crucial for adults particularly for women who “want their fetus to enjoy optimal vitamin D level,” writes Cannell.
The panel consulted with 14 vitamin D experts explains Cannell in his response, yet after reading each report, the panel decided to suppress the findings. In response, the Vitamin D Council is filing a federal Freedom of Information request to the IOM to release the 14 reports.
Dr. Cannell and others are undeterred by the panels’ findings, committed to advancing the message that higher D dosing offers scientifically-based health benefits. All parties most likely do agree that further research needs to be conducted to create more precise dosing guidelines since dosing depends on a number of factors.
"I supplement patients who are deficient and they feel better. They come in and say, 'I've been much less achy and stiff or my mood's been better since I've been taking the vitamin D,' said Alan Pocinki for Beck’s Wall Street Journal article. An internist in D.C., Pocinki says most of his patients are office workers, and 75% of them fall below the 30 ng/ml level D advocates consider adequate.
"Do we have the data to prove this conclusively? No. We don't have evidence for much of what we do in medicine, but if you wait for the evidence, you may be depriving your patients of beneficial treatments," Dr. Pocinki said.
Disclaimer: The information contained in this article is for educational purposes only and should not be used for diagnosis or to guide treatment without the opinion of a health professional. Any reader who is concerned about his or her health should contact a doctor for advice.
Additional Reading:
Calcium Supplements and Heart Health Under Review
Dementia Linked to Low Levels of Vitamin D in Elderly
Vitamin D Deficiency and Crohns Disease
Vitamin D Deficiency, Fibromyalgia, Anxiety and Depression
Cold and Flu Prevention and Vitamin D
Swine Flu Deaths in Children and Low Vitamin D
Resources:
Cavalier E, Delanaye P, Morreale A, Carlisi A, Mourad I, Chapelle JP, Emonts P. "Vitamin D deficiency in recently pregnant women."Rev Med Liege. February 2008.
Kolata, Gina, “Report Questions Need for 2 Diet Supplements.” The New York Times. November 29, 2010. Retrieved December 6th, 2010.
Laura Owens - Laura Owens has a B.S. in Psychology from Rollins College & U of FL. She is a freelance writer with expertise in motivation & wellness.
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