Something so well known that is not known …

High Levels of Vitamin D
Decrease Dementia

And that includes Alzheimer’s disease

By Will Block

W e have recently learned that high intakes of vitamin D help reduce the risk of most cancers. In fact, two recent meta-analyses have addressed this. The most recent found that cancer patients with high levels of vitamin D (at the point of diagnosis) often have better survival rates and remain in remission longer than patients who are vitamin D-deficient.1

This is not trivial. In this latest meta-analysis, 17,332 cancer patients were examined. Significant associations between circulating vitamin D levels and cancer were found. The researchers found the strongest link between vitamin D levels and survival in breast cancer, lymphoma and colorectal cancer.

Vitamin D Associated with Lower Mortality

The risk ratio for the highest versus the lowest quartile of circulating vitamin D levels was 0.55 for overall survival of colorectal cancer patients, 0.63 for breast cancer patients, and 0.48 for lymphoma patients. Higher vitamin D levels were significantly associated with reduced cancer-specific mortality for patients with colorectal and lymphoma and improved disease-free survival for patients with breast cancer or lymphoma.


Higher vitamin D levels
were significantly associated with
reduced cancer-specific mortality for
patients with colorectal and
lymphoma and improved disease-free
survival for patients with
breast cancer or lymphoma.


Only Vitamin D3 Reduces Mortality

The second meta-analysis, published in 2011, emphasizes that cholecalciferol (vitamin D3) reduces mortality in adults more than placebo, but that other forms of vitamin D such as vitamin D2* do not.2 This meta-analysis reports that vitamin D3 (cholecalciferol) reduces all-cause mortality by 6%. According to Durk Pearson & Sandy Shaw, that’s a very impressive reduction! (See “Vitamin D3, But Not Other Forms of Vitamin D Found to Reduce All-Cause Human Mortality,” in their Life Extension News in the April 2012 issue of this publication.)


* For example, ergocalciferol, alfacalcidol, or calcitriol.


This meta-analysis covered 50 trials involving 94,148 subjects with mean age 74 years, of which 79% were women. A commentary on the review concluded that, “… the results of the meta-analysis by Bjelakovic and colleagues should encourage providers to consider cholecalciferol (vitamin D3) as their preferred choice for vitamin D supplementation.”3 We would assume that this also applies to the 17,332 patient study (above).

Vitamin D Deficient Twice as Likely to Suffer Dementia and Alzheimer’s

Fig. 1. Kaplan-Meier curves for unadjusted rates of all-cause dementia and Alzheimer disease by serum 25-hydroxy­vitamin D (25(OH)D) concentrations.

LEM1410Alz_graph274.gif
(click on thumbnail for full sized image)

Vitamin D deficiency is associated with a substantially increased risk of dementia and Alzheimer’s disease in older people, according to the most rigorous study of its kind ever conducted.4 Just published in Neurology, an international team led by Dr. David Llewellyn from the University of Exeter Medical School in the UK investigated the study participants — consisting of 1,658 elderly American adults (aged 65 and over) initially free from dementia, cardiovascular disease, and stroke. The participants were then followed for six years to determine who went on to develop Alzheimer’s disease and other forms of dementia. During that time, 171 participants developed all-cause dementia, including 102 cases of Alzheimer’s disease.

Risk of Dementia Increased from 53 – 125 Percent

At the end of the study, the researchers discovered that elderly Americans who were moderately deficient in vitamin D had a 53 per cent increased risk of developing dementia of any kind, and the risk increased to 125 per cent in those who were severely deficient.

Risk of Alzheimer’s Increased from 69 – 122 Percent

Similar results were recorded for Alzheimer’s disease, with the moderately deficient group 69 per cent more likely to develop this type of dementia — jumping to a 122 per cent increased risk for those severely deficient. Considered together, it was found that those subjects most deficient in vitamin D deficiency were twice as likely to develop dementia or Alzheimer’s disease.

Given the number of cases of dementia (of which Alzheimer’s is the most severe form) which are expected to triple by 2050 as a result of rapid population aging, and given that perhaps a billion people worldwide who are currently thought to have low vitamin D levels, the results could be devastating.

The research is the first large study to investigate the relationship between vitamin D and dementia risk where the diagnosis was made by an expert multidisciplinary team, using a wide range of information including neuroimaging. Previous research established that people with low vitamin D levels are more likely to go on to experience cognitive problems, but this study confirms that this translates into a substantial increase in the risk of Alzheimer’s disease and dementia.

While vitamin D comes from three main sources — exposure of skin to sunlight, foods such as oily fish, and supplements — the older you get the less efficient you become at converting sunlight into vitamin D, making it less likely that you will be deficient and reliant on other sources. That means taking supplements. Plus, in many countries the amount of UVB radiation in winter is too low to allow vitamin D production.



Vitamin D deficiency is associated
with a substantially increased risk of
dementia and Alzheimer’s disease in
older people according to
the most rigorous study of its
kind ever conducted.


Threshold Level of Vitamin D

The UK study also found evidence of a critical point for circulating levels of vitamin D in the bloodstream, below which the risk of developing dementia and Alzheimer’s disease arises. Previously, the research team had hypothesized that this might lie in the region of 25 – 50 nmol/L. However, their new findings confirm that vitamin D levels above 50 nmol/L are most strongly associated with good brain health.

According to another study on vitamin D’s potent anticancer properties,5 “Low levels of vitamin D may be associated with increased cancer incidence and mortality in men, particularly for digestive-system cancers. The vitamin D supplementation necessary to achieve a 25(OH)D increment of 25 nmol/L may be at least 1500 IU/day.” [Emphasis added] What about more than 50 nmol/L, as suggested for good brain health? That would probably be in the range of 2000 – 4000 IU/day, though levels of 6000 – 8000 IU/day would be better.

Back to the senior researcher of the study. Dr. Llewellyn said: “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 was twice as strong as we anticipated.6

“[O]ur 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.”

Amyloid Clearance and Other Mechanisms

As an explanation of how vitamin D may act to prevent dementia and Alzheimer’s disease, the researchers point out that in vitro vitamin D increases the phagocytic clearance of amyloid plaques by stimulating macrophages and reducing amyloid-induced cytotoxicity and apoptosis in primary cortical neurons.

Previous prospective studies have established that low vitamin D concentrations in elderly adults are associated with an increased risk of cognitive decline. Also, a recent study found that amyloid-β induction of induced nitric oxide synthase, part of the inflammatory process of AD, is dependent on the disruption of the vitamin D-vitamin D receptor pathway. Another study has found that vitamin D supplementation ameliorates age-related decline in learning and memory in aged rats.

In addition, vitamin D deficiency has been linked to cerebro­vascular pathology. Other meta-analyses have established that vitamin D deficiency is associated with an increased risk of incident stroke, particularly ischemic stroke. In summary, low vitamin D concentrations may increase the risk of dementia and AD through both neurodegenerative and vascular mechanisms.

Overall the findings support the hypothesis that vitamin D may be neuroprotective and that “sufficiency” in the context of dementia risk may be in the region of 50 nmol/L.

Good for Body and Mind

Don’t take chances with your health. At the right dose level, vitamin D is plentiful and cheap. This wasn’t always the case, but now knowledgeable purveyors produce it in the right size, 2000 IU/cap. Don’t fail to take advantage of something that is exceedingly good for protecting your body and your mind.

References

  1. Li M, Chen P, Li J, Chu R, Xie D, Wang H. Review: the impacts of circulating 25-hydroxyvitamin d levels on cancer patient outcomes: a systematic review and meta-analysis. J Clin Endocrinol Metab. 2014 Jul;99(7):2327-36. doi:10.1210/jc.2013-4320. Epub 2014 Apr 29.
  2. Bjelakovic G, Gluud LL, Nikolova D, Whitfield K, Wetterslev J, Simonetti RG, Bjelakovic M, Gluud C. Vitamin D supplementation for prevention of mortality in adults. Cochrane Database Syst Rev. 2011 Jul 6;(7):CD007470.
  3. Murff HJ. ACP Journal Club. Review: cholecalciferol (vitamin D3) reduces mortality in adults; other forms of vitamin D do not. Ann Intern Med. 2011 Nov 15;155(10):JC5-04.
  4. Littlejohns TJ, Henley WE, Lang IA, et al. Vitamin D and the risk of dementia and Alzheimer disease. Neurology. 2014 Aug 6. pii: 10.1212/WNL.0000000000000755. [Epub ahead of print]
  5. Giovannucci E, Liu Y, Rimm EB, Hollis BW, Fuchs CS, Stampfer MJ, Willett WC. Prospective study of predictors of vitamin D status and cancer incidence and mortality in men. J Natl Cancer Inst. 2006 Apr 5;98(7):451-9.
  6. University of Exeter. Link between vitamin D, dementia risk confirmed. ScienceDaily. http://www.sciencedaily.com/releases/2014/08/140806161659.htm. Published August 6, 2014. Accessed August 17, 2014.


Will Block is the publisher and editorial director of Life Enhancement magazine.

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