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Healthy diet cuts Alzheimer's disease risk

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Eating a healthy diet may help reduce risk of Alzheimer's disease, a new study published in the June 2010 issue of Archives of Neurology suggests.

The study led by Yian Gu Ph.D. of Columbia University Medical Center, New York and colleagues found people eating a diet with more salad dressing, nuts, fish, poultry and certain fruits and vegetables and fewer high fat dairy products, red meat, organ meats and butter were less likely to be diagnosed with Alzheimer's disease.

"Epidemiological evidence linking diet, one of the most important modifiable environmental factors, and risk of Alzheimer's disease is rapidly increasing," Yian Gu et al. wrote as background information in the article.

"However, current literature regarding the impact of individual nutrients or food items on Alzheimer's disease risk is inconsistent, partly because humans eat meals with complex combinations of nutrients or food items that are likely to be synergistic."

The study involved 2,148 adults  aged 65 and older without dementia at baseline.  The participants were assessed for the development of dementia every 1.5 years for an average of four years during which 253 people were diagnosed with Alzheimer's disease.

Several dietary patterns were identified based on some nutrients previously shown to be associated with Alzheimer's disease risk including saturated fatty acids, monounsaturated fatty acids, omega-3 fatty acids, omega-6 fatty acids, vitamin E, vitamin B12 and folate.

The researchers found a diet high in salad dressing, nuts, fish, tomatoes, poultry, fruits and calciferous and dark and green leafy vegetables and low in high-fat dairy, red meat, organ meat and butter was associated with reduced risk of developing Alzheimer's disease.

They explained why these foods help reduce the risk. They said vitamin B12 and folate can help reduce circulating homocysteine levels, vitamin E might prevent Alzheimer's disease via its strong antioxidant effect and certain fatty acids may be related to dementia and cognitive function through atherosclerosis, thrombosis or inflammation.

Many previous studies have suggested lifestyle modifications may lead to a reduction in Alzheimer's.  Below are a brief summary of some studies reported early at foodconsumer.org. 

Previous studies have suggested certain foods or ways may help prevent Alzheimer's disease.

Green tea may fight Alzheimer's

An antioxidant found in green tea known as epigallocatechin gallate (EGCG)  may help prevent the development of amyloid fibrils, which are associated with Alzheimer's and Parkinson's disease, according to a new German study in the May 30, 2008 online edition of Nature Structural & Molecular Biology.

Erich Wanker, from the Max Delbrueck Center for Molecular Medicine in Berlin and colleagues found "the polyphenol (-)-epigallocatechin gallate efficiently inhibits the fibrillogenesis of both alpha-synuclein and amyloid-beta by directly binding to the unfolded polypeptides and preventing their conversion into toxic, on-pathway aggregation intermediates."

According to the authors, EGCG could be used to eliminate the toxic misfolded proteins in cells and prevent the formation of amyloid plaque if patients are treated.  But it is unknown whether the treatment could reverse the existing plaques.

Another study published in the April 7, 2008 issue of Brain Research showed "Green tea epigallocatechin-3-gallate (EGCG) reduces beta-amyloid mediated cognitive impairment and modulates tau pathology in Alzheimer transgenic mice."

Other studies also have suggested EGCG may be taken as a health supplement to prevent certain cancers and metabolic syndrome in addition to a range of other health benefits.


Curry prevents Alzheimer's disease

The chemical known as Bisdemethoxycurcumin in curry, which is made of Turmeric root, may help fight Alzheimer's disease, a study conducted by the David Geffen School of Medicine in Los Angeles and the Human BioMolecular Research Institute in San Diego suggested.

The researchers found Bisdemethoxycurcumin boosted immune cells called macrophages to clear amyloid beta, a protein found in the brain plagues causing Alzheimer's.

The study was published July 16, 2007 in the online early edition of the Proceedings of the National Academy of Sciences. Other observational studies have also found people who use curry often such as Indians have a lower risk of developing Alzheimer's. 


Overweight, obesity may boost Alzheimer's disease risk

Overweight or obese people may have a greater likelihood of developing Alzheimer's disease (AD) compared with those who have a normal body weight, a study reported in the Dec. 2005 issue of the Journal of Alzheimer's disease suggests.

In the new study, researchers at the Farber Institute for Neurosciences at Thomas Jefferson University in Philadelphia and Edith Cowan University in Joondalup, Western Australia found that being extremely overweight or obese were associated with an increased risk of Alzheimer's disease.

In the study of 18 extremely obese (but otherwise healthy people), researchers measured body mass index (BMI) and beta-amyloid blood levels. They found a "statistically significant correlation" between BMI and beta-amyloid.

Previous studies have demonstrated being overweight or obese is a risk factor for Alzheimer's disease.


Calorie restriction may prevent Alzheimer's

Calorie restriction boosts longevity and may help prevent aging-related Alzheimer's disease by triggering the brain activity associated with longevity,  a study, which appears in the July 2006 issue of the Journal of Biological Chemistry, suggests.

Mount Sinai School of Medicine researchers found calorie restriction based on low carbohydrate food can reduce beta-amyloid peptides in the brain of the lab mice. Conversely, a high caloric intake based on saturated fat was found to increase levels of the peptides that are linked with Alzheimer's.

Grape seed extract may help prevent Alzheimer's
A study led by Wang J and colleagues from Mount Sinai School of Medicine in New York suggests that taking grape seed extract supplements may help prevent or even treat Alzheimer's disease.

The study published on June 18 in the Journal of Neuroscience showed that grape seed polyphenolic extract significantly inhibits amyloid beta-protein aggregation into high molecular weight oligomers in vitro.

The study also showed that when orally administered to lab mice, the extract dramatically attenuates cognitive deterioration commonly experienced by Alzheimer's patients.

Extracellular accumulation of soluble high-molecular-weight oligomers has been proposed to be responsible for Alzheimer's dementia and memory deficits in mice with an disorder similar to human Alzheimer’s disease.


Red wine compound reduces Alzheimer's disease-causing peptides

Resveratrol, a compound found in red grapes and red wine, may help fight Alzheimer's disease, and possibly other amyloid-related diseases, according to a lab study published in the Nov. 11, 2005 issue of the Journal of Biological Chemistry.

For the study, Philippe Marambaud and his colleagues at the Litwin-Zucker Research Center for the Study of Alzheimer's Disease and Memory Disorders in Manhasset, New York, administered resveratrol to cells which produced human amyloid-beta, and monitored amyloid-beta levels inside and outside the cells to assess the effectiveness of resveratrol on amyloid-beta peptides. They found the treated cells had significantly lower amounts of amyloid-bata than the untreated cells.

Other researchers in past studies have suggested that resveratrol may act as an antioxidant to help get rid of free radials provoked by amyloid-beta peptides in the brain. Free radials generated from fatty acids are believed to cause Alzheimer's.


Mediterranean diet lowers Alzheimer's risk in American cohort

A study published in the April, 2006 issue of Annals of Neurology found Americans who ate a Mediterranean diet consisting of  high amounts of fruits, vegetables, legumes, cereals, some fish and alcohol, and little dairy and meat had a reduced risk for Alzheimer's disease as they aged.

Nikolaos Scarmeas of Columbia University Medical Center followed 2,258 non-demented people in New York City who had no dementia when entering the study. The subjects were examined every 18 months during a period of 4 years.

Compared with those in the group that adhered to a Mediterranean diet the least, subjects in the middle tertile had a 15 to 21 percent lower risk of Alzheimer's disease, and those in the highest tertile had a 39 to 40 percent lower risk, the researchers found.

The association remained significant even after considering potential confounders such as age, gender, ethnicity, education, caloric intake, BMI, smoking and comorbid conditions.


High Blood Sugar Level Increases Risk Of Alzheimer's Disease

People with high blood sugar levels may be at an increased risk of developing Alzheimer's disease, researchers report. Alzheimer's disease is linked with type 2 diabetes, but researchers say the link may develop much before patients are identified as diabetic.

The condition with high blood sugar levels that is not yet in the established diabetes range is called pre-diabetes. Researchers from Stockholm's Karolinska Institute said that people with higher than normal blood sugar levels could be at an increased risk for developing Alzheimer's disease at a later stage.

The researchers presented the findings of their nine-year study on the opening day of the 10th International Conference on Alzheimer's Disease and Related Disorders in Madrid in 2006.

David Liu

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