Both being more physically active and adhering to a Mediterranean-type diet appears to be associated with reduced Alzheimer’s risk, according to a new report in the August 12, 2009 issue of the Journal of the American Medical Association (JAMA). While previous studies have only investigated the association between either physical activity or diet and Alzheimer’s disease risk separately, this new research explored their combined association
Findings of Observational Study Warrant Further Research in Controlled Clinical Trial to Clarify the Role of These and Other Possible Factors Contributing to AD Risk
Both being more physically active and adhering to a Mediterranean-type diet appears to be associated with reduced Alzheimer’s risk, according to a new report in the August 12, 2009 issue of the Journal of the American Medical Association (JAMA).
While previous studies have only investigated the association between either physical activity or diet and Alzheimer’s disease risk separately, this new research explored their combined association.
“Often times people who exercise also follow a healthy diet and vice versa. We wanted to tease out which of these two behaviors may be associated with lower risk for AD, or if the combination of the two is associated with decreased risk even further,” said Nikos Scarmeas, M.D., lead author of the study and associate professor of clinical neurology in the Department of Neurology, in the Sergievsky Center and in the Taub Institute for Research on Alzheimer’s Disease and the Aging Brain at Columbia University Medical Center.
This population-based study in a multi-ethnic community living in Northern Manhattan, observed 1880 elderly subjects, with an average age of 77. The participants were interviewed about their level of physical activity and dietary habits, and their responses were then summarized into two single scores. The study subjects were then followed to observe which subjects went on to develop Alzheimer’s over the course of approximately five and a half years.
To learn about their physical exercise routine, participants were queried about their activity during a two week period prior to the interview. The subjects were asked to quantify how many times they engaged in physical activity and for how long. Participants were queried regarding three categories of activities: vigorous activity (i.e., jogging etc), moderate activity (i.e., hiking, bicycling, etc), and light activity (i.e., golfing, gardening, etc).
For the dietary portion of the study, subjects were asked regarding their food consumption over the course of the previous year. Their responses were then grouped into nine food categories, the sum of which represented the Mediterranean-type diet score. A Mediterranean-type diet is typically characterized by high intake of fish, vegetables, legumes, fruits, cereals and monounsaturated fatty acids; relatively low intake of dairy products, meats and saturated fats; and moderate alcohol consumption.
The study found that those subjects who were very physically active had a 33 percent risk reduction of Alzheimer’s; those who adhered more strongly to a Mediterranean-type diet had a 40 percent risk reduction. In addition, Dr. Scarmeas and his colleagues found that there was a gradual decreasing risk for Alzheimer’s in study participants who were reporting that they were both exercising a lot and following a diet closer to the Mediterranean-type: those subjects had a 60 percent reduction in their risk for developing Alzheimer’s disease.
“So it seemed that the more that they were doing in terms of both diet and exercise, the lower was their risk for the disease,” said Dr. Scarmeas.
Dr. Scarmeas further noted that even low degrees of physical activity reported by these elderly study subjects seemed to be associated with having a protective effect against Alzheimer’s
“This study is important because it shows that people may be able to alter their risk of developing Alzheimer’s by modifying their lifestyles through diet and exercise,” said Dr. Scarmeas.
Dr. Scarmeas cautions, however, that this was an observational, epidemiological study – based on interviews with study subjects on their physical activity routines and dietary habits. Therefore, the associations were based on what subjects reported and no randomized interventions were done. Only a clinical trial type of design would offer additional information to help clarify the role of these behaviors and reveal other potential contributing factors.
“We know that some part of Alzheimer’s is related to genetic changes and as time goes on we discover more and more of these changes. But it is also possible that non-genetic changes, including lifestyle and behavior, may also be affecting our brain health and our risk of developing brain diseases, like Alzheimer’s, maybe in combination with our genetic predisposition,” said Dr. Scarmeas. “We need to understand and learn more about the exact biological mechanisms that may connect physical activity and diet with the biological changes of Alzheimer’s disease.”
“Since the benefits of following a healthy diet and remaining active have already been suggested as beneficial in other disease prevention and since based on the present and other similar studies we have some preliminary hints that this may also be helpful for brain health, it seems advisable that we emphasize not only to patients, but to healthy individuals, too, the importance of these lifestyle behaviors in affecting our overall health,” said Dr. Scarmeas.
Authors of the JAMA study include: Nikolaos Scarmeas, M.D.; Jose A. Luchsinger, M.D.; Nicole Schupf, Ph.D.; Adam M. Brickman, Ph.D.; Stephanie Cosentino, Ph.D.; Ming X. Tang, Ph.D.; and Yaakov Stern, Ph.D.
This study was supported by the National Institute on Aging.
Note: In the same issue of JAMA, Dr. Scarmeas co-authored with researchers from the Université Victor Ségalen Bordeaux 2 in France, a separate study titled, “Adherence to Mediterranean Diet, Cognitive Decline, and Risk of Dementia.” Dr. Scarmeas expressed his encouragement about the study, which helps to validate findings by Dr. Scarmeas and his colleagues on the association between the Mediterranean diet and a reduced risk for Alzheimer’s disease. More specifically, the French study found an association between higher adherence to this diet and slower rates of cognitive decline. No associations with risk for developing Alzheimer’s disease were noted in this study, but this was clearly due to methodological limitations including the relatively small number of study subjects who developed Alzheimer’s disease according to Dr. Scarmeas. Dr. Scarmeas also noted the significance of the fact that the French study looked at a different population, and in particular, a Mediterranean one.
The Taub Institute for Research on Alzheimer’s Disease and the Aging Brain at Columbia University Medical Center is a multidisciplinary group that has forged links between researchers and clinicians to uncover the causes of Alzheimer’s, Parkinson’s and other age-related brain diseases and discover ways to prevent and cure these diseases. It functions in close cooperation with the Department of Pathology and Cell Biology, the Department of Neurology and the Gertrude H. Sergievsky Center.
Columbia University Medical Center provides international leadership in basic, pre-clinical and clinical research, in medical and health sciences education, and in patient care. The medical center trains future leaders and includes the dedicated work of many physicians, scientists, public health professionals, dentists, and nurses at the College of Physicians and Surgeons, the Mailman School of Public Health, the College of Dental Medicine, the School of Nursing, the biomedical departments of the Graduate School of Arts and Sciences, and allied research centers and institutions. Established in 1767, Columbia’s College of Physicians and Surgeons was the first institution in the country to grant the M.D. degree and is among the most selective medical schools in the country.
Source: Columbia University Medical Center. ( www.cumc.columbia.edu.)
1 University of East Anglia, United Kingdom
* To whom correspondence should be addressed. E-mail: a.hart@uea.ac.uk.
Accepted 6 June 2009
Objective. Dietary linoleic acid, an n-6 polyunsaturated fatty acid, is metabolised to arachidonic acid, a component of colonocyte membranes. Metabolites of arachidonic acid have pro-inflammatory properties and are increased in the mucosa of patients with ulcerative colitis. The aim of this investigation was to conduct the first prospective cohort study investigating if a highdietary intake of linoleic acid increases the risk of developing incident ulcerative colitis.
Design & Setting. Dietary data from food frequency questionnaires were available for 203 193 men and women aged 30-74 years, resident in the UK, Sweden, Denmark, Germany or Italy and participating in a prospective cohort study (EPIC – European Prospective Investigation intoCancer and Nutrition). These participants were followed up for the diagnosis of ulcerative colitis. Each case was matched with four controls and the risk of disease calculated by quartile of intake of linoleic acid adjusted for gender, age, smoking, total energy intake and centre.
Results. A total of 126 participants developed ulcerative colitis (47% women) after a median follow-up of 4.0 years (range 1.7-11.3 years). The highest quartile of intake of linoleic acid was associated with an increased risk of ulcerative colitis (OR=2.49, 95% CI=1.23 -5.07, p=0.01) witha significant trend across quartiles (OR for trend = 1.32, 95% CI=1.04-1.66, p=0.02).
Conclusions. The data support a role for dietary linoleic acid in the aetiology of ulcerative colitis.An estimated 30% of cases could be attributed to having dietary intakes higher than the lowest quartile of linoleic acid intake.
Source: Gut. Published Online First: 23 July 2009. doi:10.1136/gut.2008.169078
Uncooked meat products enhanced with food additives may contain high levels of phosphorous and potassium that are not discernable from inspection of food labels, according to a study appearing in an upcoming issue of the Clinical Journal of the American Society Nephrology (CJASN). This can make it difficult for people to limit dietary phosphorous and potassium that at high levels are harmful to kidney disease patients.
Kidney disease patients on dialysis must watch their intake of dietary phosphate so that their blood phosphate levels do not rise. This is important because high blood phosphate levels may cause premature death in dialysis patients. Kidney disease patients also must limit their intake of potassium, because high blood potassium levels can cause sudden death.
One growing source of dietary phosphorous and potassium is through “enhanced” fresh meat and poultry products. These foods are injected with a solution of water with sodium and potassium salts (particularly phosphates) as well as antioxidants and flavorings. While ingesting phosphates and potassium can be dangerous for dialysis patients, there is no requirement that these ingredients be included in nutrition labels. There also have been no studies on the levels of phosphates and potassium contained in fresh meat and poultry products that have been “enhanced.”
Richard Sherman, MD, and Ojas Mehta, DO (University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School), examined the potassium and phosphate content in a variety of “enhanced” and additive-free meat and poultry products available in local supermarkets. They found that products that were labeled as “enhanced” had an average phosphate concentration that was 28% higher than additive-free products, with some products almost 100% higher.
Potassium content was variable. Additive-free products all contained < 387 mg of potassium per 100 gm of protein while 5 of the 25 products with additives that were studied contained at least 692 mg of potassium per 100 gm of protein (maximum 930 mg/100 gm). Most foods with phosphate and potassium additives reported the additives on the labeling; however, 8 of the 25 “enhanced” products included in the study did not list the additives.
“The burden imposed on those seeking to limit dietary phosphorus and potassium could be ameliorated by more complete food labeling by manufacturers,” the authors wrote.
The study was funded by grants from Genzyme, Inc. and Dialysis Clinics, Inc. The authors reported no other financial disclosures.
The article, entitled “Phosphorus and Potassium Content of Enhanced Meat and Poultry Products: Implications for Patients Receiving Dialysis,” will appear online athttp://cjasn.asnjournals.org/ on July 23, 2009, doi 10.2215/CJN.02830409.
