August 21, 2012
Many people take antioxidant supplements like vitamins C and E in the hopes of warding off Alzheimer’s disease and other diseases of aging. But in a new study, published in the Archives of Neurology, researchers report that a four-month course of antioxidant supplements did not appear to be effective in altering the course of Alzheimer’s disease.
Some earlier studies have suggested that people who eat an antioxidant-rich diet, packed with vitamin E, vitamin C and other nutrients, may help reduce the risk of Alzheimer’s disease, though other studies have found antioxidants to be of little benefit. Antioxidants act to mop up the highly reactive oxygen molecules, called free radicals, that build up during daily living and that can damage cells throughout the body, including the brain. Antioxidants have long been touted to prevent heart disease and cancer. It was hoped they might also slow or prevent that brain deterioration that occurs in Alzheimer’s disease.
In the current study, researchers at the University of California, San Diego, set out to assess the effects of antioxidants on Alzheimer’s by measuring levels of proteins in the cerebrospinal fluid, or CSF, which bathes the spinal cord and brain. Levels of certain proteins act as markers for the onset of Alzheimer’s disease, measuring byproducts of Alzheimer’s hallmarks like beta-amyloid and tau. If protein levels showed a healthy trend, the scientists theorized, the antioxidants might be having a beneficial effect on the brain.
The study included 78 patients with mild to moderate Alzheimer’s disease who were divided into three groups and given supplements for 16 weeks. Some were given 800 IU per day of vitamin E (the form known as alpha-tocopherol), along with 500 mg a day of vitamin C plus 900 mg a day of alpha-lipoic acid, another antioxidant. A second group got 400 milligrams of coenzyme Q10, a popular antioxidant supplement, three times a day. The third group, which served as a control, got look-alike placebo pills.
None of the groups showed any improvements in terms of CSF markers directly related to Alzheimer’s disease. They did show improvement in one marker, indicating that those who were taking the vitamin E, vitamin C, lipoic acid cocktail may be undergoing less oxidative damage to the brain. However, this group also scored worse on tests of memory than those in the placebo group, raising the concern that they may be undergoing faster cognitive decline.
The researchers also found that while coenzyme Q10 was safe and well tolerated in patients, it did not appear to offer benefits for the brain, as measured by any of the markers.
It’s difficult to use the results of this study to advise whether Alzheimer’s patients or those at risk for Alzheimer’s should or should not take antioxidant supplements. First, the study was of short duration (4 months) and was fairly small (78 patients). Clinical trials for potential Alzheimer’s drugs of this size and duration have not previously produced results that hold up in larger trials. Therefore, it is unlikely that a study of this size and duration could provide information telling us whether the supplements affected the course of Alzheimer’s in these patients.
Also, the study was primarily concerned with measuring proteins in CFS, which does not necessarily reflect how each patient is doing as far as disease progression is concerned or whether their memory and thinking skills are actually changing (though some cognitive tests were employed).
Finally, the study does not address the question as to whether taking antioxidant supplements by healthy people might affect their risk of developing Alzheimer’s.
Nutrition experts point out that many foods contain a rich mix of antioxidants, so that taking one or several supplements does not duplicate the benefits of eating healthful foods. Numerous studies suggest that eating a rich variety of fruits and vegetables or a Mediterranean diet may help to ward off Alzheimer’s and a range of other ailments.
Douglas R. Galasko, MD; Elaine Peskind, MD; Christopher M. Clark, MD; et al: “Antioxidants for Alzheimer Disease: A Randomized Clinical Trial With Cerebrospinal Fluid Biomarker Measures.” Archives of Neurology, published online March 19, 2012. doi:10.1001/archneurol.2012.85