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Kenneth H. Cooper MD, MPH


How Effective are the DASH Diet and the Mediterranean Diet at Reducing Mortality Risk? The Cooper Center Longitudinal Study.

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Live well

Monday, Mar 19, 2018

It has long been known that dietary pattern is associated with several chronic disease risk factors.  According to the American Cancer Society, among non-tobacco users dietary pattern as well as physical activity are considered to be the two most important modifiable lifestyle factors in determining cancer risk. Among the many chronic disease risk factors impacted by dietary pattern are blood cholesterol, glucose, and triglyceride levels, blood pressure, hemoglobin A1C, obesity, inflammation, and serum vitamin D levels. Two dietary patterns that have received much attention in the medical literature are the Dietary Approaches to Stopping Hypertension (DASH) diet and the Mediterranean diet. In certain populations such as hypertensives and older individuals, DASH has been shown to reduce all-cause mortality. On the other hand, results from the Mediterranean diet regarding mortality have been somewhat inconsistent. Because some Cooper Clinic patients complete a dietary record as part of their preventive exam, researchers sought to examine the relationship between dietary patterns and specific food group intake with the risk of all-cause and cardiovascular disease mortality in a group of middle-aged patients.
The study evaluated 11,376 healthy Cooper Clinic men and women with an average age of 47 years who were examined between 1987 and 1999. Each patient completed a 3-day diet record prior to their preventive exam. In order to help provide accurate self-reported data, written instructions and photographs of serving sizes were provided to patients by Clinic dietitians. Based on this diet record, each patient was given a DASH Diet Score and a Mediterranean Diet score. The DASH diet score was based on average daily intake of fruits, vegetables, nuts, legumes, dairy, whole grains, red meat, sodium, and added sugars. Patients were placed into one of 5 groups (quintiles) based on their overall DASH diet score and by each DASH component. The Mediterranean diet score was based on average daily intake of vegetables, fruits, nuts, legumes, grains, fish, dairy, and meat. Patients were placed into quintiles based on their overall Mediterranean diet score and by each Mediterranean diet component.

During an average follow-up of 18 years, there were 841 total deaths; of which 249 were related to CVD. While performing the data analyses, researchers carefully controlled for factors that might have muddied the waters such as age, smoking, body mass index, family history, and physical activity level. As shown in Figure 1, each quintile increase in the overall DASH diet score was associated with a 6% decrease in the risk of all-cause mortality. A higher vegetable intake seemed to drive most of this decrease in risk. This was the first study to show that the DASH diet is associated with a decreased risk of all-cause mortality in a population that was healthy at baseline. However, the DASH diet score was not significantly associated with cardiovascular mortality in the current analyses.

The overall Mediterranean diet score was not significantly associated with risk of all-cause or cardiovascular disease mortality. However, when examining specific components of the Mediterranean Diet, a higher intake of fruits, nuts, and whole grains was associated with an approximately 35% decrease in risk of cardiovascular mortality. Lastly, for both dietary patterns, those with the highest intake of solid (saturated and trans) fats and added sugars (e.g. non-diet soda, candy, fake fruit juice, etc.) had the highest risk of all-cause mortality.

The main takeaway from this study is that increased intake of vegetables, fruits, nuts, and whole grains are associated with significant reductions in overall mortality risk, while a high intake of solid fats and added sugars is associated with a significant increase overall mortality risk. These findings support current dietary recommendations to consume more plant-based foods, fewer animal products that are high in saturated fat, and less added sugars. Of note, vegetables, fruits, and whole grains are complex carbohydrates, which should further dispel the hip and trendy myth that all carbohydrates are ‘bad’ and should be limited or avoided in the diet. Variety, balance, and moderation are the keys to healthful eating for all!

Shah, N., Leonard, D., Finley, C., Rodriguez, F., Sarraju, A., Barlow, C….Maron, D. (2018). Dietary patterns and long-term survival: a retrospective study of healthy primary care patients. Am J Med, 131:1, 48-55. 1016/j.amjmed.2017.08.010

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