(Released Aug. 12, 2005)
Study featured in the 1st issue of Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association
Chicago, Ill. – Newly published research suggests that older adults whose diets include a total folate intake at or above the recommended dietary allowance (RDA) are at a significantly reduced risk of developing Alzheimer’s disease. The study appeared in the inaugural issue of Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association.
Folates are B-vitamin nutrients that are found in foods such as bananas and oranges, leafy green vegetables, asparagus, broccoli, liver, and many types of beans and peas.
According to the researchers, study participants who reported intake at or above the 400 microgram recommended daily allowance of folates had a 55 percent reduction in risk in developing Alzheimer’s. They also noted that most people in the study who reached that intake level did so by taking folic acid supplements. This suggests that many people do not get the recommended amount of folates in their diet.
In “Reduced risk of Alzheimer’s disease with high folate intake: The Baltimore Longitudinal Study of Aging,” Maria Corrada, Sc.D., Assistant Professor of Neurology, University of California Irvine; Claudia Kawas, M.D., Department of Neurology and Neurobiology & Behavior, University of California Irvine; and colleagues examined whether total intake (diet plus supplements) of antioxidant vitamins (E, C, carotenoids) and B vitamins (folate, B6, and B12) is associated with a reduced risk of Alzheimer’s. They analyzed the diets of 579 non-demented men and women age 60 and older and compared the nutrient intake of those who later developed AD to the intake of those who did not develop the disease.
“Because this was an observational study, it is possible that other factors may be responsible for the reduction in risk,” said Corrada. “People with a high intake of one nutrient are likely to have a high intake of several nutrients, and may generally have a healthy lifestyle. Additional studies are necessary to determine whether folate has a direct, causal role in risk reduction for Alzheimer’s and to determine appropriate recommendations.”
To the researchers’ knowledge, this is the first prospective study to report on the association between folate intake and Alzheimer’s risk and to analyze antioxidants and B vitamins simultaneously.
“While this research needs to be confirmed, what it suggests is strongly in accordance with the diet-related recommendations of the Alzheimer’s Association’s Maintain Your Brain® campaign,” said William Thies, Ph.D., vice president, Medical & Scientific Affairs, Alzheimer’s Association. “A brain-healthy diet is lower in fat and cholesterol and higher in antioxidants, such as those contained in dark colored fruits and vegetables. And, a brain-healthy diet is most effective when combined with regular physical and mental activity and social interaction.”
More about folates
Folates can help reduce the risk of certain serious and common birth defects called neural tube defects, which affect the brain and spinal cord. Research suggests that they may also be beneficial in heart disease by decreasing homocysteine levels. In 1996, the Food and Drug Administration (FDA) published regulations requiring the addition of folic acid to enriched breads, cereals, flours, corn meals, pastas, rice, and other grain products. Folic acid is a synthetic form of folate that is found in supplements. Folic acid supplementation should always include vitamin B12 supplementation because folic acid can mask an underlying vitamin B12 deficiency, which can cause permanent damage to the nervous system. In fact, taking any one of the B vitamins for a long period of time can result in an imbalance of other important B vitamins. For this reason, it is generally important to take a B complex vitamin with any single B vitamin.
More about the study
The researchers used data from the Baltimore Longitudinal Study of Aging (BLSA) to identify the relationship between dietary factors and Alzheimer’s disease risk. Between 1984 and 1991, study volunteers provided detailed dietary diaries for a typical seven-day period. Participants were 579 nondemented volunteers (359 men, 220 women) aged 60 and older. Total nutrient intake per day was estimated as the intake from diet and supplements combined.
Participants were tracked for up to 14 years (mean follow-up = 9.3 years). Over the course of the study, 57 of the participants developed Alzheimer’s. The researchers found that those with higher intake of folates (RR, 0.41; 95% confidence interval [CI], 0.22 to 0.76), vitamin E (RR, 0.56; 95% CI, 0.30 to 1.06), and vitamin B6 (RR, 0.41; 95% CI, 0.20 to 0.84) had lower rates of the disease. However, when the three vitamins were analyzed together, only folates (RR, 0.45; 95% CI, 0.21 to 0.97) were associated with a significantly decreased risk of Alzheimer’s.
After taking into consideration intake of other vitamins, study participants with total intake of folate at or above 400 micrograms had a 55 percent reduction in the risk of developing Alzheimer’s. Levels much above the RDA did not provide additional protection. No association was observed between intake of vitamin C, carotenoids, or vitamin B12 and the development of Alzheimer’s.
According to the researchers, one of the limitations of the study is the lack of diversity in the participants’ education and ethnicity – well-educated, mostly white volunteers. Therefore, the results of this study may not be generalizable to other populations. This relative homogeneity, however, may minimize the possible confounding effects of education and ethnicity.
The National Institute on Aging initiated the Baltimore Longitudinal Study of Aging in 1958 to prospectively examine the normal aging process. The study was originally undertaken at the Gerontology Research Center (NIA) and the Department of Neurology at Johns Hopkins.
Folate, homocysteine and Alzheimer’s
According to the researchers, there are several possible ways that folate intake may impact the risk of developing of Alzheimer’s, some of which may be related to its ability to reduce homocysteine levels. These include:
High homocysteine levels are known to contribute to vascular disease, and studies show strong connections between risk factors for vascular disease and Alzheimer’s.
There is evidence that high homocysteine levels may be directly linked to risk of Alzheimer’s. For example, recent animal studies suggest that high homocysteine (and low folic acid levels) may make brain cells more vulnerable to damage from beta-amyloid.
There is some evidence that homocysteine may cause direct toxicity to neuronal cells.
About Alzheimer’s & Dementia
Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association, published quarterly, will present the latest original, peer-reviewed, basic and clinical research advances in the field, including early detection, prevention and treatment. Coverage will extend from healthy brain aging to all forms of dementia, and include leading edge material of interest to both the basic scientist and practitioner. Alzheimer’s & Dementia will focus on bridging the knowledge gaps across diverse investigations ranging from the bench to the bedside.
About The Alzheimer’s Association
The Alzheimer’s Association, the world leader in Alzheimer research, care and support, is dedicated to finding prevention methods, treatments and an eventual cure for Alzheimer’s. For nearly 25 years, the donor-supported, not-for-profit Alzheimer’s Association has provided reliable information and care consultation, created supportive services for families, increased funding for dementia research, and influenced public policy changes. The Alzheimer’s Association’s vision is a world without Alzheimer’s disease. For more information, visit www.alz.org or call 800-272-3900.
Editor’s Note: Anticipated dates for the first issues of Alzheimer’s & Dementia are: August 2005, October 2005, January 2006, and April 2006. Complimentary subscriptions can be made available for news media.
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