Researchers at the UCSD and Creighton University at Omaha, Nebraska say the National Academy of Sciences (NAS) Institute of Medicine (IOM)’s Recommended Dietary Allowance (RDA) for vitamin D intake is miscalculated and underestimated — not by any small measure, but by a whopping factor of ten.
In a letter published this month in the journal Nutrients, the scientists explain that they’ve confirmed a calculation error in the IOS metrics that has been previously noted by other investigators, by factoring is a data set pertaining to a different population.
In 2014, University of Alberta School of Public Health statisticians, Professor Paul Veugelers PDF, PhD, MSc and John Paul Ekwaru, published an Open Access paper entitled “A Statistical Error in the Estimation of the Recommended Dietary Allowance for Vitamin D” (Published: 20 October 2014 Nutrients 2014, 6(10), 4472-4475; doi:10.3390/nu6104472) in the online journal Nutrients showing that the Institute of Medicine (IOM) had made a major calculation error in its recommended dietary allowance (RDA) for vitamin D.
Dr. Cedric F. Garland, Dr.P.H, an adjunct professor at UC San Diego’s Department of Family Medicine and Public Health says his team was able to confirm findings last year reported by Dr. Paul Veugelers in Nutrients last October.
The March, 2015 Nutrients letter’s coauthors observe that using the same data set as had the IOM panel, investigators Veugelers and Ekwaru showed that the Recommended Dietary Allowance (RDA) for vitamin D had been underestimated by an order of magnitude, and an RDA of 8895 IU per day would have been appropriate, with the qualification that there was some uncertainty in that estimate, inasmuch as this value required an extrapolation from the available data, which did not include individuals receiving daily vitamin D inputs above 2400 IU/da.
“Both these studies suggest that the IOM underestimated the requirement substantially,” notes Dr. Garland in a Creighton U. release. “The error has broad implications for public health regarding disease prevention and achieving the stated goal of ensuring that the whole population has enough vitamin D to maintain bone health.”
Not only bone health. A study claimed to be the most robust of its kind ever conducted, reported last summer in the journal Neurology by an international team led by Dr. David Llewellyn a Senior Research Fellow in Clinical Epidemiology at the University of Exeter Medical School in Exeter U.K. found Vitamin D deficiency to be associated with substantially increased risk of dementia and Alzheimer’s disease in older people, finding that severely Vitamin D deficient study participants were more than twice as likely to develop dementia and Alzheimer’s disease than persons with higher vitamin D intake.
Dr. Llewellyn is a Chartered Psychologist and an Associate Fellow of the British Psychological Society whose research focuses on risk factors, overlapping pathologies and functional consequences of Alzheimer’s disease and dementia, particularly where vascular and metabolic pathways are implicated. He conducted the first population-based studies to identify the associations between vitamin D deficiency and cognitive impairment in the Health Survey for England and cognitive decline in the InCHIANTI study, both of which were widely reported in the international media.
Investigating elderly Americans who took part in the Cardiovascular Health Study, the Llewellyn research group discovered that moderately vitamin D deficient adults had a 53 percent higher risk of developing any kind of dementia, with risk increasing to 125 percent in severely deficient individuals. Similar results were recorded pertaining to Alzheimer’s disease — the moderately deficient group 69 percent more likely to develop Alzheimer’s, and a 122 percent increased risk for the severely vitamin D deficient cohort.
The study, partially-funded by the Alzheimer’s Association, the Mary Kinross Charitable Trust, the James Tudor Foundation, the Halpin Trust, the Age Related Diseases and Health Trust, the Norman Family Charitable Trust, and the National Institute for Health Research Collaboration for Leadership in Applied Research and Care South West Peninsula (NIHR PenCLAHRC), was published as an Open Access article in the August 6 2014 online issue of the journal Neurology, the medical journal of the American Academy of Neurology. Entitled “Vitamin D and the risk of dementia and Alzheimer disease“ (Neurology, August 2014 DOI: 10.1212/WNL.0000000000000755), the paper is coauthored by Thomas J. Littlejohns, MSc, William E. Henley, PhD, Iain A. Lang, PhD, Cedric Annweiler, MD, PhD, Olivier Beauchet, MD, PhD, Paulo H.M. Chaves, MD, PhD, Linda Fried, MD, MPH, Bryan R. Kestenbaum, MD, MS, Lewis H. Kuller, MD, DrPH, Kenneth M. Langa, MD, PhD, Oscar L. Lopez, MD, Katarina Kos, MD, PhD, Maya Soni, PhD* and David J. Llewellyn, PhD; variously affiliated with the University of Exeter Medical School (T.J.L., W.E.H., I.A.L., K.K., M.S., D.J.L.), Exeter, UK; Department of Internal Medicine and Geriatrics (C.A., O.B.), Angers University Hospital, Angers, France; Herbert Wertheim College of Medicine (P.H.M.C.), Florida International University, Miami; Mailman School of Public Health (L.F.), Columbia University, New York; Kidney Research Institute, Division of Nephrology (B.R.K.), University of Washington, Seattle; Departments of Epidemiology (L.H.K.) and Neurology and Psychiatry (O.L.L.), University of Pittsburgh, PA; Division of General Medicine (K.M.L.), Veterans Affairs Ann Arbor Center for Clinical Management Research, Ann Arbor, MI; and the Institute for Social Research and the Institute for Healthcare Policy and Innovation (K.M.L.), University of Michigan, Ann Arbor.
The scientists investigated 1,658 adults aged 65 and over, all of whom were able to walk unassisted and free from dementia, cardiovascular disease, and stroke at the beginning of the study. The participants were then followed for six years to investigate who went on to develop Alzheimer’s disease and other forms of dementia.
Dr. Llewellyn comments in a U. of Exeter release: “We expected to find an association between low Vitamin D levels and the risk of dementia and Alzheimer’s disease, but the results were surprising — we actually found that the association with vitamin D ‘was twice as strong as we anticipated. Clinical trials are now needed to establish whether eating foods such as oily fish or taking vitamin D supplements can delay or even prevent the onset of Alzheimer’s disease and dementia. We need to be cautious at this early stage and our latest results do not demonstrate that low vitamin D levels cause dementia. That said, our findings are very encouraging, and even if a small number of people could benefit, this would have enormous public health implications given the devastating and costly nature of dementia.”
There are estimated to be some 44 million dementia cases worldwide — and that demographic expected to triple by 2050 due to rapid population aging. Meanwhile, a billion people worldwide are thought to have deficient vitamin D levels with a consequence being that many older adults could experience poorer health as a result.
The Exeter release notes that this research was the first large study to investigate the relationship between vitamin D and dementia risk in which diagnoses were made by an expert multidisciplinary team, and based on a wide range of information including neuroimaging. Previous research has already established that individuals with low vitamin D levels are more likely to eventually experience cognitive difficulties, but this study confirms that vitamin D deficiency translates into substantially greater Alzheimer’s disease and dementia risk. Vitamin D comes from three main sources — exposure of skin to sunlight, foods such as oily fish, and supplements. Older people’s skin can be less efficient at converting sunlight into Vitamin D, making them more likely to be deficient and reliant on other sources. In many countries the amount of UVB radiation in winter is too low to allow vitamin D production.
The study also found evidence of threshold level of Vitamin D circulating in the bloodstream, below which risk of developing dementia and Alzheimer’s disease increases. Having previously hypothesized that this threshold level might be in the 25-50 nmol/L range, their new findings confirm that vitamin D levels twice that high, i.e.: above 50 nmol/L are most strongly associated with good brain health.
A commentary article recently published in Nature Reviews Neurology by John E. Morley, the Dammert Professor of Gerontology, Director of the Division of Geriatric Medicine, and Director of the Division of Endocrinology at Saint Louis University Medical Center at St. Louis, Missouri, entitled “Dementia: Does vitamin D modulate cognition?“ (Published online 21 October 2014 Nature Reviews Neurology 10, 613–614 (2014) doi:10.1038/nrneurol.2014.193) observes: “epidemiological evidence strongly suggests that circulatory levels of 25-hydroxyvitamin D below 50 nmol/l are associated with cognitive impairment and the development of dementia. A number of biochemical mechanisms could explain these effects; however, interventional studies to date have revealed disappointingly little.”
The Alzheimer’s Research Society says “Vitamin D deficiency is common in the elderly because of the skins reduced capacity to synthesize it with age and because of decreased sun exposure, which is necessary for the synthesis of the vitamin. It has been reported that higher blood levels of Vitamin D are associated with a reduced risk for Alzheimer’s disease. If you have a relative with early signs of dementia, you can request that their doctor determine if your relative is deficient in Vitamin D with a simple blood test. This is important, as the elderly require higher levels of Vitamin D than younger adults.”
These research findings and observations are consistent with the Creighton UCSD team’s critique of the IOM’s vitamin D intake guidelines.
The IOM-recommended vitamin D intake is a modest 600 IU/day for persons younger than age 70 years, and 800 IU/day for older individuals. “Calculations by us and other researchers have shown that these doses are only about one-tenth those needed to cut incidence of diseases related to vitamin D deficiency,” Dr. Garland contends.
Dr. Robert P. Heaney, M.D. Professor of Medicine and John A. Creighton University Professor Emeritus, Professor of Medicine and John A. Creighton University Professor Emeritus says: “We call for the NAS-IOM and all public health authorities concerned with transmitting accurate nutritional information to the public to designate, as the RDA, a value of approximately 7,000 IU/day from all sources.
“This intake is well below the upper level intake specified by IOM as safe for teens and adults, 10,000 IU/day,” Dr. Garland notes. Other authors of the Nutrients letter were C. Baggerly and C. French, of the San Diego-based voluntary organization GrassrootsHealth, and E.D. Gorham, Ph.D., of UC San Diego.
In his Creighton U. blog, Dr. Heaney explains how he believes the NAS-IOM statisticians arrived at their erroneous vvitaminD RDA conclusion, noting that the Canadian statisticians Veugelers and Ekwaru took precisely the same studies as the IOM had used and demonstrated that the requirement to ensure that 97.5% of the population would have a value of at least 20 ng/mL, was 8,895 IU per day, while the IOM recommendation is less than 1/10 that. “When my colleagues and I analyzed the large GrassrootsHealth dataset,” he notes, “we calculated a value closer to 7,000 IU per day, still a full order of magnitude higher than the estimate of the IOM, and not substantially different from the estimate of Veugelers and Ekwaru.”
Dr. Heaney observes that this is an important mistake, not only because it should never have been allowed inclusion in a major policy document, but also because IOM recommendations have substantial effects on a wide array of government programs including nutritional standards for US military, for school lunch programs, for WIC and many others, both in the United States and in Canada.
He further notes that while there is almost no public awareness of this IOM’s error or its implications in the United States, a large nutritional health foundation located in Calgary (Pure North SEnergy Foundation) took out a series of half page advertisements in Canada’s self-styled national newspaper the Toronto Globe and Mail and other newspapers alerting Canadians that the error was made and that they need more vitamin D than current policy indicates (http://www.purenorth.ca/?page_id=1356)
The Pure North SEnergy Foundation advocacy letter by the organizations’s founder and Chief Accountability Officer Allan Markin notes:
“Vitamin D plays an important role in overall health. Vitamin D is used by nearly every cell in the body and has an effect on every system. Since it acts as a protector and regulator, it enhances the functioning of our body’s systems to protect against disease. Simply put, optimizing vitamin D levels results in better health.
“Other studies have also found that if Canadians optimized their intake of Vitamin D an estimated 37,000 premature deaths could be avoided annually…
We believe that it is imperative the Health Canada guidelines be revised and that Canada’s current approach to health change from treating disease to optimizing health.”
Dr. Heaney says Health Canada has agreed to undertake an independent reanalysis of the vitamin D RDA calculation, although results are not yet available and what action the federal ministry will take action is still uncertain.
In the U. S., Encinatas, California based GrassrootsHealth a nonprofit public health research organization dedicated to moving public health messages regarding vitamin D from science into practice., is currently running what it calls the “D*action population intervention program” to address the vitamin D deficiency epidemic worldwide. Under the D*action umbrella are programs focused on the entire population.
A link to vitamin D testing can be found here:
Journal letter references:
Heaney, R.P. et al. 2015. Letter to Veugelers, P.J. and Ekwaru, J.P., A Statistical Error in the Estimation of the Recommended Dietary Allowance for Vitamin D. Nutrients 2014, 6, 44724475; doi:10.3390/nu6104472 URL: http://www.mdpi.com/2072-6643/7/3/1688
Veugelers, P.J. et al. 2014. A Statistical Error in the Estimation of the Recommended Dietary Allowance for Vitamin D. Nutrients 2014, 6(10), 4472-4475; doi:10.3390/nu6104472
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University of California San Diego
University of Exeter Medical School
Nature Reviews Neurology
University of Alberta School of Public Health
The Alzheimer’s Research Society
Pure North SEnergy Foundation
University of California San Diego
University of Exeter Medical School
University of Alberta School of Public Health
Saint Louis University Medical Center