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Professional Dialogue: Does the Mediterranean Diet Prevent Alzheimer’s?

July 25, 2017   /

Alzheimer’s disease is the most common form of dementia, with roughly 4.5 million people older than 65 years of age affected. While the causes of Alzheimer’s disease are not clear, it appears they are a combination of issues relating to aging, genetics, molecular changes in the brain, and environment/lifestyle factors.

Studies are looking at the connection between diet and Alzheimer’s in an attempt to help understand this disease. Research indicates that some of the risk factors for heart disease and stroke, such as high blood pressure, high cholesterol, and low levels of folate, also may increase the risk of Alzheimer’s disease. The purported relationship between vascular disease and Alzheimer’s disease could potentially lead to a link between diet and Alzheimer’s disease. The use of this information by dietetics practitioners in certain positions will help to reduce the rates of Alzheimer’s disease in the future. As our understanding of the vascular disease/Alzheimer’s disease connection is supported by research, registered dietitians will need to keep up to date on these recommendations to help provide the latest information to a growing population of older Americans.

A Medscape review of the key dietary influences on Alzheimer’s disease is available at http://www.medscape.com/viewarticle/466037_print. These influences include antioxidant nutrients such as vitamins C and E (foods vs supplements), dietary fat composition, and fish and n-3 fatty acids. One of the dietary patterns that has received interest in preventing Alzheimer’s disease is the Mediterranean diet. The diet is typically low in saturated fat and high in fruits and vegetables, with unsaturated fats, lean meats, and low-fat dairy foods recommended in moderate amounts. The Mayo Clinic’s Web site provides a concise summary of this eating pattern at http://www.mayoclinic.com/health/mediterranean-diet/CL00011.

A well-publicized study on the relationship between diet and Alzheimer’s disease was released in the Annals of Neurology in April 2006, available at (http://www.cumc.columbia.edu/dept/sergievsky/cnd/pdfs/MediterraneanDietandRisk.pdf. This study concluded that the Mediterranean Diet may protect against Alzheimer’s disease and that a dose/response relationship may exist (ie, better adherence to the diet results in a greater decrease in the risk of developing Alzheimer’s disease).

In 2004, Public Health Nutrition published a literature review titled “Mediterranean Diet and Cognitive Decline,” abstract available at http://www.medscape.com/medline/abstract/15482625. This study concluded that “essential components of the Mediterranean diet—MUFA [monounsaturated fatty acid], cereals, and wine—seem to protect against cognitive decline.

The vascular disease/Alzheimer’s disease connection is especially intriguing because of the possibility of using statin medications to treat Alzheimer’s disease. According to the Medscape review of diet and Alzheimer’s disease, it seems that cholesterol is an important component in Alzheimer’s disease. Studies of dietary saturated fat also note an association between saturated fat intake and Alzheimer’s disease. Some studies of patients who are prescribed statin drugs found a significantly lower risk of Alzheimer’s disease compared to similar patients who were not prescribed these medications.

Despite numerous studies citing a connection between diet and Alzheimer’s disease, no conclusive evidence exists to show that dietary changes will prevent Alzheimer’s disease. The Dietary Reference Intakes for vitamins C and E (published in 2000) do not recommend antioxidant supplements to prevent diseases. At this time, the evidence points to a connection between diet and Alzheimer’s disease. Further research may help confirm a connection.

Implications for the dietetics practitioner
A diet low in saturated fat and high in whole grains, fruits, and vegetables, with moderate levels of unsaturated fats, such as the Mediterranean Diet pattern. may have a protective effect against both Alzheimer’s disease and cardiovascular disease. This type of eating pattern is recommended as part of the Dietary Guidelines for Americans, which is recommended for all patients, including those who are at risk for Alzheimer’s disease. As further research is conducted, more specific dietary recommendations for Alzheimer’s disease may emerge.

 

 

References and recommended readings

Féart C, Samieri C, Barberger-Gateau P. Mediterranean diet and cognitive function in older adults. Curr Opin Clin Nutr Metab Care. 2010;13:14-18.

Institute of Medicine, Food and Nutrition Board. Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids: A Report of the Panel on Dietary Antioxidants and Related Compounds, Subcommittees on Upper Reference Levels of Nutrients and Interpretation and Uses of Dietary Reference Intakes, and the Standing Committee on the Scientific Evaluation of Dietary Reference Intakes. Washington, DC; National Academy Press; 2000. Available at: http://www.nal.usda.gov/fnic/DRI//DRI_Vitamin_C/vitamin_c_full_report.pdf. Accessed October 6, 2011.

Jick H, Zornberg GL, Jick SS, Seshadri A, Drachman DA. Statins and the risk of dementia. Lancet. 2000;356:1627-1631.

Panza F, Solfrizzi V, Colacicco AM, et al. Mediterranean diet and cognitive decline. Public Health Nutr. 2004;7:959-963, 2004.

Scarmeas N, Stern Y, Tang MX, Mayeux R, Luchsinger JA. Mediterranean diet and risk for Alzheimer’s disease. Ann Neurol. 2006;59:912-921.

Solfrizzi V, Panza F, Frisardi V, et al. Diet and Alzheimer’s disease risk factor or prevention: the current evidence. Expert Rev Neurother. 2011;11:677-708.