Researchers from the U.K. reported in a recent article in the periodical Neurology that high levels of Vitamin D reduce the risk of developing dementia and Alzheimer’s disease. This provides more evidence to recommend taking extra vitamin D as an anti-aging (preventive) medicine action. You should get your blood levels over 50 nmol/L. Doing so potentially decreases your risk of developing dementia and Alzheimer’s disease as you grow older.
The study utilized another study that was started in 1992. Initially they evaluated 1658 elderly patients from 1992 to 1999 in the United Kingdom (David Llewellyn from the University of Exeter Medical School). This original study was to detect the development of cardiovascular disease in these patients. When that study began, none of the patients had dementia, heart disease or stroke and blood samples were obtained from them for analysis. In 2008, a separate group of researchers evaluated the Vitamin D levels in these patients and reported their results in the Neurology Journal.
The results demonstrated that as these patients got older, there was a correlation between their prior level of Vitamin D and the development of dementia years later. They found that the elderly people with less vitamin D in their blood were more likely to develop dementia and Alzheimer’s disease. At the end of the study, 171 participants in the study developed dementia, which included 102 cases of Alzheimer’s disease.
Those whose vitamin D levels were considered “severely deficient” (defined as vitamin D level <25 nmol/L) at the start of the study were twice as likely to develop these conditions as those with levels >50 nmol/L (desired levels). Those starting with vitamin D levels between 25 to 50 nmol/l (i.e. “deficient”) had a 50% increased risk of developing these problems.
The absolute risk of developing these neurological diseases in this study was discussed. Of all the participants evaluated in the study, 10 percent of the group with desired levels of Vitamin D developed dementia, which increased to 15 and 22 percent of vitamin D deficient and severely deficient people, respectively.
The researchers did not test whether taking vitamin D supplements or changing diet plans would have affected dementia risk. Moreover, they said, “It is too early to tell whether improving vitamin D levels helps to delay or prevent dementia – clinical trials are now urgently needed.”
However, the study authors concluded that: “Our results confirm that vitamin D deficiency is associated with a substantially increased risk of all-cause dementia and Alzheimer disease.” One author, Autier, speculated that this association may be a consequence of low vitamin D associated with an increase in inflammation which is common in many chronic conditions, including dementia, Alzheimer’s disease, heart disease and cancer.
Autier coauthored a systemic review of vitamin D and ill health published in The Lancet in 2013. In that paper he discussed the importance of keeping Vitamin D levels up and this association with reducing inflammation: “inflammatory processes that are common in many chronic conditions, infectious diseases, aging, dementia and even depression… are strongly involved in Alzheimer’s disease, and these processes are likely to be present well before Alzheimer’s disease is clinically detectable.” Higher vitamin D levels are associated with a decreased risk of colorectal cancers. 
Dr. Robert L. True, from TrueMD.com, has recommended that patient’s have their blood levels of vitamin D checked. If below 50 nmol/L, he recommends they take extra vitamin D to boost their levels above this range. There are essentially no side effects from doing this, and doing so could decrease your risks of developing dementia, and other problems.
It’s easy to just take this pill. If it can help, why not do so as long as it’s safe, which it is. Most people should take around 5,000 units per day; some, up to 10,000 units per day. See your physician to know the best course of action for you.
Littlejohns, TJ, et al. “Vitamin D and the risk of dementia and Alzheimer disease.” Neurology, Sept. 2,2014, 83(no.10): 920-928.
Aurtier, P, et al, “Vitamin D status and ill health: a systematic review”, The Lancet Diabetes & Endocrinology, Volume 2, Issue 1, Pages 76 – 89, January 2014