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  • The Alzheimer's Disease and Memory Disorders Center

  • Diet and Dementia: Toxic Preservatives Contribute to Alzheimer's Disease

  • Suzanne de la Monte, MD, MPH, discusses her research into the relationship between diet and Alzheimer's disease.
    It's no secret that eating right can help us be healthier, fitter, and even avoid cancer. Now, research proves that it can also reduce our chances of developing Alzheimer's disease.

    Suzanne M. de la Monte, MD, MPH, a physician-scientist at Rhode Island Hospital and professor of neuropathology, neurosurgery, and neurology at The Warren Alpert Medical School of Brown University, found a critical link between our modern diet, characterized by processed "convenience" foods, and the disease. Though scientists had already determined that Alzheimer's disease, a devastating form of dementia, was characterized by tangles and plaques in the brain, no one had determined the cause.

    De la Monte discovered the connection when she was investigating another disease thought to be regulated by poor responses to insulin. When de la Monte and her research team conducted an experiment in which they disabled the insulin and insulin receptors in the brain, they were surprised to find they had recreated Alzheimer's disease.

    Diabetes mellitus and Alzheimer's disease are both characterized in part by a deficiency in the production of insulin. Insulin in the body is not only produced in the pancreas, as commonly known, but in the brain. De la Monte found that in Alzheimer's disease, the production of insulin and similar substances in the brain almost cease, creating what she calls "diabetes in the brain." But what was causing the drop in production of brain insulin?

    The Culinary Connection

    When de la Monte studied national statistics, she made another startling discovery. In the United States, fast food chain and meat processing company sales increased more than eightfold from 1970 to 2005. During this time, grain consumption also increased fivefold, including grains grown using nitrogen-containing fertilizers. Rates of Alzheimer's, diabetes, and fatty liver disease increased dramatically in people ages 55 and over during this period, while medical science and health care steadily improved. "One cannot explain this trend on the basis of just genetics," says de la Monte. "So the best correlation we can find is how we eat and how we live."

    De la Monte says lifestyle trends are to blame. Americans are ingesting more nitrates and nitrites, which are added to many foods as preservatives, colorings and flavorings. They are also present in tobacco. Under acidic conditions, such as in the stomach, or when foods are prepared at high temperatures such as frying or flame broiling, nitrates and nitrites convert to nitrosamines, which can be carcinogenic. At the same time, we are taking in more calories, high-fat foods and sugars, leading to fatty liver disease, which in turn produces toxins and insulin resistance that damages the brain.

    What We Can Do

    De la Monte says the most important lesson to be learned from her research is that if we created these trends, we could reverse them. Early findings from The Nun Study, a longitudinal study of aging and Alzheimer's disease using data collected from the older School Sisters of Notre Dame, show that habits adopted even very early in life can strongly influence the risk of developing Alzheimer's and other diseases later. Since children are particularly susceptible to toxins, good nutrition at an early age appears to be one of the best defenses against developing the disease.

    De la Monte advises parents to fill their shopping carts with fresh, wholesome foods, and to avoid feeding their children foods containing nitrates and nitrites. The most potentially harmful foods are those that are processed, smoked, or preserved, mainly smoked meats, bacon, and processed cheeses. The ingredient labels of such foods will include "sodium nitrite." Parents should also limit their children's consumption of "white" foods such as white bread, pasta and rice, whose high sugar content can adversely affect metabolism and insulin production and contribute to obesity. Adults may wish to limit their consumption of beer, as many brands may contain very high contents of nitrates to lengthen their shelf life.

    De la Monte also encourages the support of local farming over factory farms, and healthy habits such as exercise, avoiding smoking, and staying intellectually stimulated. "You only have one body, and one brain, so we should take care of them."