Is diet related to dementia? For a long time, researchers have known two things: (i) poor dietary habits increase the risk of getting heart disease, and (ii) having heart disease increases the risks of dementia (1). The next question followed naturally: Does poor diet itself increase the risk of dementia? Researchers now say, Yes (2, 3, 4).
Here are three central findings.
First, the Mediterranean Diet has been found to reduce the chances of suffering cognitive declines from both Alzheimer’s’ Disease and normal aging (5).
Just what is the Mediterranean Diet? It has these elements:
How does this diet protect the brain?
Olive Oil and Fish Oil.Both are central in this diet, as both are high in MUFA. In an analysis of more than 700 research participants in Europe, the intake of olive oil (MUFA) showed positive association with cognitive function over the course of 6-13 years (6, 7, 8, 9).
Grains. High caloric intake from cereals and breads does not increase the likelihood of cognitive declines.In fact, an inverse correlation has been found – that is, the higher the proportion of calories taken from cereals and breads, the lower the rates of Alzheimer’s. In effect, cereals and breads become a protective factor (2).
Fruits and Vegetables. A careful study that adjusted for age, sex, and other demographics found that those who reported drinking three glasses of fruit/vegetable juice a week had a 75% lower risk of developing Alzheimer’s Disease, compared with those who reported drinking less than one glass a week (10).
Second,saturated fat has been shown to increase the risk of cognitive decline in both North American and European samples of research participants. The European study was large, including of 700+ participants, and found a connection between the consumption of these fats and a decline in cognitive function. (7). Saturated fats such as stearic acid are found in cookies and pastries, as well as many processed meat and dairy products.
In a very broadly based meta-analytic study (an analysis of 18 previously published studies), a series of regression analyses were performed on people age 65 and older in 11 countries. The primary finding was that diets high in calories from saturated fats showed the highest correlations with receiving an Alzheimer’s diagnosis (2).
Third, certain vitamin deficiencies reduce memory capacities, and also have a negative effect on other cognitive functioning. Especially problematic are vitamin deficiencies of B6, B12, flavonoids, folates, and antioxidants such as vitamins E and C. Conversely, dietary flavonoids have a protective effect against dementia (11).
A partial list of flavonoids includes blueberries, strawberries, black tea, all citrus fruits, red wine, parsley, peanuts, cocoa, parsley, broccoli, brussels sprouts, red bell peppers, spinach, and garlic.
Green leafy vegetables are especially important in this list, as they contain more Vitamin E than other vegetables, and have shown a strong inverse relationship with cognitive decline – the higher the intake of leafy greens, the slower the cognitive decline (12).
Summary. After citing nearly 300 references in a lengthy review of studies examining the links between diet and Alzheimer’s, reviewers concluded with this summative sentence: “(F)ollowing dietary advice for lowering the risk of cardiovascular and metabolic disorders, high levels of consumption of fats from fish, vegetable oils, non-starchy vegetables, low glycemic index fruits and a diet low in foods with added sugars and with moderate wine intake should be encouraged. Hopefully this will open new opportunities for the prevention and management of dementia and AD.” (13)
13. Diet and Alzheimer’s disease risk factors or prevention: The Current Evidence. Solfrizzi, V., Panza, F., Frisardi. V., Seripa, D., Logroscino, G., ; Bruno P., Imbimbo,B., Pilotto, A. Expert Review of Neurotherapeutics.
John Robertson, Ph.D.