Can vitamins help prevent Alzheimer's disease?
Many HSI members are well aware that an elevated level of homocysteine (an amino acid) increases the risk of heart disease and other cardiovascular problems. And they also know that foods and supplements rich in vitamins B6, B12, and folate can help reduce homocysteine.
Less well known, however, is a demonstrated link between high homocysteine and an increased risk of Alzheimer's disease (AD) and dementia.
So we return to the original question: Can vitamins (specifically, the ones mentioned above) help prevent Alzheimer's disease?
Last year, researchers from the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University recruited more than 320 healthy older men from a Veterans Affairs study on aging. At baseline, all of the men completed food-frequency questionnaires, and blood was drawn from each subject to measure B vitamins and homocysteine. Over the following three years the men took occasional tests to monitor cognitive function.
At the conclusion of the study, researchers reported these results:
High homocysteine levels were associated with a decline in recall memory
High folate levels were significantly linked to verbal fluency
Subjects with elevated folate levels had fewer declines in spatial copying (a drawing test that measures the brain's ability to understand and reproduce geometric figures)
Writing in the American Journal of Clinical Nutrition, the USDA authors concluded that, "Low B vitamin and high homocysteine concentrations predict cognitive decline."
Vitamins B6, B12, and folate have been proven to help metabolize homocysteine. These nutrients are abundant in asparagus, lentils, chickpeas, most varieties of beans, and especially spinach and other leafy green vegetables. But many people don't absorb B vitamins well, so in addition to these food sources a good B-complex supplement is often required to lower homocysteine levels.
According to several studies, supplements of the antioxidant amino acid N-acetylcysteine (NAC) may also lower homocysteine levels.
In 2001 I told you about a study that showed how NAC improved cognitive function in patients with probable Alzheimer's disease. The 24-week study of 47 subjects revealed that those participants who took NAC showed improvement in nearly every outcome measure, without experiencing any negative side effects.
Once homocysteine levels are addressed, there are other nutrients that may offer further protection from Alzheimer's. In the e-Alert "Form Rides with Function" (4/20/05), I told you about two studies from Johns Hopkins University that show how two key vitamins may support cognitive function.
In the first study, nearly 580 subjects, aged 60 or older, were followed for more than seven years. A diet high in vitamin E (spinach, eggs, nuts, seeds, avocados, tomatoes, peaches and blackberries) was strongly associated with a significant reduction of Alzheimer's risk. Intake of dietary vitamin C was found to be somewhat useful in reducing AD risk, but less effective than vitamin E.
Nearly two years later, another Johns Hopkins team interviewed more than 4,700 subjects aged 65 or older. Supplement intake was assessed, as well as the prevalence of dementia and Alzheimer's disease, from 1995 to 1997, and again from 1998 to 2000. Evaluation of the data showed that in the first phase, those who took supplements of vitamins C and E combined had a 78 percent lower risk of AD. In the second phase, the percentage dropped to 64, but still indicated a significant level of protection.
In addition, Alzheimer's risk was even lower among subjects who took a vitamin E supplement along with a multivitamin that contained vitamin C.
Jenny Thompson -HSI [Also, be sure to do your Sudoku!]