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“A critical weekly review of important new research findings for health-conscious readers”

VITAMIN D REDUCES RISK OF COGNITIVE DECLINE & DEMENTIA

Regular readers of this column are already well aware of the preventive effects of Vitamin D with respect to falls in the elderly, certain cancers, and cardiovascular disease.  (My new book, “A Cancer Prevention Guide for the Human Race,” which is scheduled to be published in August, 2010, contains an exciting and comprehensive update on the role of Vitamin D in cancer prevention.)  Now, a newly published research study, which appears in the current issue of the Archives of Internal Medicine, has linked low Vitamin D levels in the blood with an increased risk of cognitive decline and dementia in adults over the age of 65.

A total of 858 adults at or over the age of 65 participated in this prospective public health study, which was conducted over a period of 7 years.  All of these study volunteers underwent extensive evaluation of their cognitive function, using validated, standardized tests, when they entered into the study.  All patients also underwent testing of their blood for Vitamin D levels.  This extensive evaluation and testing was then repeated every 3 years during the course of this important clinical research study.

The results of this study indicated that patient volunteers with low Vitamin D levels in the blood (less than 25 nmol/liter), when compared with volunteers with normal blood levels of Vitamin D (75 nmol/liter, or higher), experienced significant declines in their intellectual function over the course of this study.  Indeed, the patient volunteers with decreased Vitamin D levels in their blood were as much as 60 percent more likely to experience progressive cognitive decline or dementia over the relatively brief duration of this study, when compared with the patients who had normal levels of Vitamin D in their blood! 

The results of this study are very similar to the findings of a similar study, which has just been published in the journal Neurology.  In this particular study, an inadequate level of Vitamin D in the blood of elderly men and women was associated with a significantly increased risk of cognitive decline and dementia from all causes, including Alzheimer’s disease and stroke.  Moreover, abnormalities of the brain, as detected by MRI scans, were also more commonly observed in patients who were deficient in Vitamin D.

Vitamin D deficiency is very common in older men and women.  An estimated 80 percent of people over the age of 65 have inadequate levels of Vitamin D in their blood, while as many as 45 percent of older men and women also have severe Vitamin D deficiency.

The results of these two studies strongly suggest that adequate levels of Vitamin D in the blood may be associated with a significantly reduced risk of aging-associated cognitive decline and dementia in older men and women, in addition to improving muscle strength, decreasing the risk of certain cancers, and decreasing the risk of cardiovascular disease. 

Not everyone should take large doses of Vitamin D, however, as the unmonitored use of this potent hormone-like vitamin can cause dangerous elevations in the level of calcium in the blood, as well as calcifications in the soft tissues of the body, kidney failure, pancreatitis, and gastrointestinal ulcers.  (Prior to starting Vitamin D supplements, you should certainly discuss the risks and benefits of Vitamin D supplementation with your physician.)

To learn more about the critical role of Vitamin D and the risk of cancer, look for the publication of my new landmark book, “A Cancer Prevention Guide for the Human Race,” in the August of this year. 

Disclaimer: As always, my advice to readers is to seek the advice of your physician before making any significant changes in medications, diet, or level of physical activity

Dr. Wascher is an oncologic surgeon, a professor of surgery, a cancer researcher, an oncology consultant, and a widely published author

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Welcome to Weekly Health Update

“A critical weekly review of important new research findings for health-conscious readers”

GINKGO BILOBA, MEMORY & COGNITIVE HEALTH

Regular readers of this column know that I have a strong interest in lifestyle- and diet-based approaches to disease prevention, but that I insist on rigorous, high-quality research-based data before I can recommend a particular lifestyle or dietary modification to my readers (or to myself).  Many past columns have reviewed the findings of research studies with favorable results associated with specific nutritional or other lifestyle approaches to disease prevention.  However, this week’s column will report on a newly published prospective clinical research trial that calls into question the supposed clinical value of the traditional Chinese medicine herb Ginkgo biloba in reducing the cognitive decline associated with aging and Alzheimer’s disease.

Previously published public health research data, based upon low-powered research methods, have suggested that dietary supplementation with Ginkgo biloba might be able to improve memory and cognition, particularly in older adults.  However, more recent data, based upon more robust types of clinical research, have called this assumption into question (as well as previous claims that Gingko biloba can delay or reverse the cognitive decline associated with Alzheimer’s disease).  Now, a newly published prospective, randomized, double-blind, placebo-controlled clinical trial of Gingko biloba supplementation in older adults in the United States appears to have definitively resolved the controversy about the value of Gingko biloba in maintaining memory, and other high level cognitive functions, in older adults. 

Ginkgo biloba trees are often referred to as living fossils, as they are known to survive for 1,500 years or more, and their presence has been documented within fossil-bearing rocks more than 270 million years old.  Although ancient fossils containing the distinctive bilobed leaves of Ginkgo biloba trees have been found on multiple continents, modern day Gingko trees now grow naturally only in China (although they have been widely cultivated, over a period of centuries, throughout Asia, and particularly in Japan and Korea).    

A new highly-powered prospective clinical research trial evaluating Ginkgo biloba supplementation appears in this week’s issue of the Journal of the American Medical Association.  More than 3,000 adults between the ages of 72 and 96 years participated in this placebo-controlled research trial, with an impressive average patient follow-up duration of more than 6 years.  These patient volunteers were secretly randomized to one of two groups.  The patients in the “experimental group” received 120 mg of Ginkgo biloba extract twice daily during the course of this study, while the “control group” of patients received an identical-appearing placebo (“sugar pills) twice daily.  (As this was a double-blind study, neither the patient volunteers nor the researchers knew which patients were receiving Gingko pills and which were receiving the placebo pills until after the research study was completed.) 

Multiple validated cognitive screening exams were given to all of these older patient volunteers during each year of the study, and the rate of annual decline in cognitive function was then compared between the two groups of patient volunteers.  Areas of cognitive function that were specifically tested for in this high-powered prospective clinical research trial included memory, attention, visual-spatial abilities, language function, and overall executive brain function.  (Note: these same cognitive function tests are also routinely utilized to assess cognitive function in patients with Alzheimer’s disease.)

Unfortunately, there was absolutely no difference observed or measured in the rate of decline in cognitive function between the two groups of older patient volunteers, indicating the lack of any clinically detectable benefit in age-related cognitive decline associated with high-dose supplementation with Ginkgo biloba.

(As an editorial aside, the Journal of the American Medical Association (JAMA) is to be commended for publishing this rigorously performed clinical research trial and its Level One research findings, as there is a well-known bias against publishing clinical research studies with “negative findings,” such as this study, among prestigious medical journals.)

Although this is the second recent high-level prospective clinical research trial that has found absolutely no clinical benefit in preserving or improving cognitive function in older adults associated with Ginkgo biloba supplements, there may still be potential clinical applications for this ancient herbal remedy in view of its known ability to improve blood flow through networks of small blood vessels in the body.  There is also some research evidence available suggesting that Ginkgo biloba may have potentially important anti-inflammatory properties, and that these properties might be clinically useful in some chronic inflammatory diseases, such as ulcerative colitis (Ginkgo biloba, ulcerative colitis & colorectal cancer).  For now, however, the overwhelming available clinical research evidence indicates that Ginkgo biloba appears to offer no benefit to older patients in terms of either preserving or improving memory, or in improving other areas of higher cognitive function.

Disclaimer: As always, my advice to readers is to seek the advice of your physician before making any significant changes in medications, diet, or level of physical activity