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NEW YORK (Reuters Health) - New research suggests that low vitamin D levels in the body are associated with thinking or "cognitive" impairments in older men, but whether vitamin D supplements can help is not yet known. In the study, an investigation of European men, subjects with low levels of vitamin D scored worse on a standard test of cognitive ability than did their peers with normal levels, Dr. David M. Lee, from the University of Manchester, UK, and co-researchers found. Although, the authors emphasize, the difference in scores was not that great.

Nutrients, endpoints, and the problem of proof. Heaney RP. 2008 W. O. Atwater Memorial Lecture J Nutr. 2008 Sep;138(9):1591-5. PMID: 18716155 To sum up, I think that there would be general agreement to the effect that nutrition is important, despite the fact that the still growing number of failed trials of individual nutrients might suggest that no nutrient actually made much of a difference, a conclusion that is absurd on its face and ought to have alerted us to the possibility that there was something wrong with how we were investigating the matter. To provide the proof needed to sustain revised intake recommendations, we shall have to find a design better suited to nutrients than the randomized controlled trial as currently implemented, and we need to develop a series of global indices, nutrient by nutrient, which better capture the polyvalent nature of most nutrients. Perhaps it would be useful for the ASN, in collaboration with concerned governmental entities such as the USDA, to convene a workshop to address these structural issues. Such deliberation may well be arduous and frustrating, but it is terribly important and, in my view, well worth the effort.

ScienceDaily (Aug. 25, 2009) - Low levels of vitamin D are known to nearly double the risk of cardiovascular disease in patients with diabetes, and researchers at Washington University School of Medicine in St. Louis now think they know why. They have found that diabetics deficient in vitamin D can't process cholesterol normally, so it builds up in their blood vessels, increasing the risk of heart attack and stroke. The new research has identified a mechanism linking low vitamin D levels to heart disease risk and may lead to ways to fix the problem, simply by increasing levels of vitamin D.

Vitamin D deficiency is a very serious health problem. Most people tend to think of it only in terms of skeletal problems; however, it is much more than that. Vitamin D deficiency has now been linked with a multitude of neoplasms, autoimmune dysfunction, compromised innate immunity and neurodevelopment in utero. Vitamin D is made in huge amounts when we go into intense sun. A fair-skinned individual can produce approximately 20,000 IU in 10 minutes' time with a total body exposure. A person with significant pigmentation will require up to 10 times the exposure to make an equivalent amount. In the winter at the latitude of Chicago, even a fair person cannot photo-produce vitamin D from mid-October through March. Thus, it is VERY important to have a realistic vitamin D recommendation as the current 200 IU/day recommendation is a joke

For many years, vitamin D was boring--even to doctors. Because it was considered good for bones and not much else, multitaskers like vitamin A, B vitamins and vitamin E hogged all the press. But recent studies have thrust this long-neglected nutrient into the spotlight. Scientists now think vitamin D may affect everything from diabetes to cancer. They're also finding that many people don't have enough of it.

"So why is Dr Vieth so frustrated? You might think he'd have cause for celebration. But for him and other vitamin D researchers around the world, the good news comes with a bitter aftertaste. They believe they can prove vitamin D could help millions live longer and be healthier and yet they have not been able to convince their own governments. In the US and Canada, official vitamin D policy is set by the Institute of Medicine. And in the opinion of Vieth, the current recommendations - 200 International Units per day for people under 50, 400 for people aged 51-70, and 600 for those 71 and older - are outrageously low. Bruce Hollis, professor of paediatrics at the Medical University of South Carolina, calls 400 IU a day "a joke". That's because the best research suggests that to achieve the higher vitamin D blood levels associated with disease prevention, most adults in the US would need to take 1,000-2,000 IU a day: five to 10 times more than the current official recommendation for adult In 1999, Reinhold Vieth (pictured right) published a review of vitamin D research in response to the IOM conclusions. In it, he argued that there was no evidence that amounts lower than 20,000 IU a day could be toxic. "Throughout my preparation of this review, I was amazed at the lack of evidence supporting statements about the toxicity of moderate doses of vitamin D," Vieth wrote. Studies have since shown 10,000 IU a day of vitamin D to be safe. While any substance will become toxic in excess, vitamin D researchers today accept that the current vitamin D recommendations could be more than quadrupled with no fear of toxicity.!

"I discussed in my last post how Dr Vieth has a model of tissue 1,25(OH)2D synthesis and degradation in which the level of active substance is pretty well independent of blood vitamin D level, provided the level is either rising or stable. I think it is also worth pointing out that he is talking, hypothetically, about tissue 1,25(OH)2D, not plasma level... As we know, almost nothing is known about tissue 1,25(OH)2D control. By Vieth's hypothesis tissue 1,25(OH)2D is OK so long as there is at least SOME vitamin D present in plasma and the level dose not vary too much. Obviously there is a level below which you can have as much of the enzyme for converting vitamin D to the active form as you like, if there is no vitamin D in your blood you can't make any 1,25(OH)2D in your tissues, or in your kidneys for export to your blood to control calcium levels. At the lower extremes we have rickets and osteomalacia. These are clear cut, unarguable markers of vitamin D deficiency, in the absence of confounding factors (there are a few)."

"Hi! This is Amy Proal. I wrote the article referenced at the start of the thread about vitamin D. Dr. Marshall is not concerned with vitamin D toxicity. Rather his molecular modeling research has clarified the actions of the two vitamin D metabolites 25-D and 1,25-D. The Vitamin D Receptor (VDR) is a fundamental receptor of the body - it controls the expression thousands of genes, as well as the activity of the innate immune system and the antimicrobial peptides. If you think of the VDR as a switch, 25-D (which is a corticosteroid) turns it off (inactivates it) and 1,25-D turn it on (activates it). What is commonly believed among vitamin D researchers is that if people supplement with extra vitamin D it will be converted into 1,25-D and activate the VDR. Unfortunately, Marshall's work revealed that the type of vitamin D derived from supplements and sun remains, for the most part, in it's precursor form 25-D. This means that the extra vitamin D we get from fortified food products and supplements is turning the VDR off, not on. That causes a decrease in immune function and gene transcription."

"March 18, 2009 | Marlene Busko Palm Harbor, FL - In a large study of adolescents, low serum levels of 25-dihydroxyvitamin D (25[OH]D) strongly predicted prevalence of hypertension, hyperglycemia, and metabolic syndrome [1]. The findings were reported at the AHA 49th Annual Conference on Cardiovascular Disease Epidemiology and Prevention. Adolescents with vitamin-D levels in the lowest quartile were almost four times more likely to have metabolic syndrome than those with vitamin-D levels in the highest quartile. "I think that is quite alarming," lead author Dr Jared P Reis (Johns Hopkins Medical Institutions, Baltimore, MD) said in an AHA podcast issued to the media."