December 23, 2007
A varied diet rich in fish, fruits and vegetables may lower your risk of Alzheimer's disease, a large new study from France suggests. Daily consumption of fruits and vegetables and weekly consumption of fish were all linked to a decreased risk of dementia. Opting for omega-6 oils, on the other hand, the kind of fats commonly found in packaged foods, at the expense of omega-3s, found in fish, walnuts and other nuts, could increase the risk of developing memory problems, the researchers report. It's not that omega-6 oils are unhealthy. Indeed, certain omega-6 oils are essential nutrients required for normal health and must be obtained from food. However, when omega-6 oils are consumed in great excess compared to omega-3's, problems may ensue.
The findings appeared in Neurology, the medical journal of the American Academy of Neurology. For the study, researchers examined the diets of more than 8,000 men and women living in three French cities -- Bordeaux, Dijon, and Montpelier. All the participants were over age 65 and free of dementia at the beginning of the study. Over the next four years, 183 of the seniors developed Alzheimer's disease, and 98 developed another type of dementia.
The investigators found that people who regularly consumed omega-3 rich oils, such as canola oil, flaxseed oil, and walnut oil, reduced their risk of dementia by 60 percent compared to people who did not regularly consume such oils. People who ate fruits and vegetables daily also reduced their risk of dementia by 30 percent compared to those who didn't regularly eat fruits and vegetables. The study also found people who ate fish, also high in omega-3s, at least once a week had a 35 percent lower risk of Alzheimer's disease and 40 percent lower risk of dementia, but only if they did not carry the APO-E4 gene that increases the risk of Alzheimer's. "Given that most people do not carry the Apo-E4 gene, these results could have considerable implications in terms of public health," said study author Pascale Barberger-Gateau of INSERM, the French National Institute for Health and Medical Research, in Bordeaux, France.
"However, more research is needed to identify the optimal quantity and combination of nutrients which could be protective before implementing nutritional recommendations." In addition, the study found people who did not carry the Apo-E4 gene and consumed an unbalanced diet characterized by regular use of omega-6 rich oils, but not omega-3 rich oils or fish, were twice as likely to develop dementia compared to those who ate less omega-6 rich oils, which include sunflower or grape seed oil. The study did not find any association between a lower risk of dementia and consuming corn oil, peanut oil, lard, or meat. Nor did it report a link between drinking wine and a healthy brain. Other research has noted that fats from meat may be bad for the brain, while a drink or two of red wine may help to keep memory intact.
"While we've identified dietary patterns associated with lowering a person's risk of dementia or Alzheimer's, more research is needed to better understand the mechanisms of these nutrients involved in these apparently protective foods," said Dr. Barberger-Gateau. Population studies such as this one can be unreliable, because people do not always report accurately all the foods they have consumed and there are so many factors besides diet at play. Still, they may suggest general trends about the foods we eat and their effects on overall health.
The study continues a long line of research showing that a varied diet rich in fruits, vegetables, and heart-healthy fats may be good for the brain. Colorful fruits and vegetables are high in antioxidants that help to protect blood vessels throughout the body, including the brain. Fish and nuts contain omega-3 fatty acids such as DHA, which has been linked to brain health. A varied diet high in these foods may help to reduce inflammation, which researchers believe may be linked to Alzheimer's, heart disease, and other ailments.
P. Barbrger-Gateau, PhD; C. Raffaitin, MD; L. Letenneur, PhD; et al: "Dietary Patterns and Risk of Dementia: The Three-City Cohort Study." Neurology, Volume 69, pages 1921-1930.