The Brain-Diet Connection

Morgan Davis, RD, LDN

It’s no news flash that what you eat can influence your risk of developing some chronic diseases such as diabetes, cardiovascular diseases and some cancers.  But, did you know that your daily dish may affect brain function as you age?  While a healthful diet and exercise have been long time players in weight management and prevention of many chronic diseases, these factors are also being recognized as influential in protection of the aging brain.

Normal Cognitive Decline and Beyond

Age-related cognitive decline (ARCD) is a natural phenomenon, occurring as part of the normal aging process- this may include decreased ability to recall facts and mild decrease in concentration.  However, sometimes we see this manifested in a more extreme condition such as dementia or Alzheimer’s disease, which are not a part of normal aging.  These conditions are not only detrimental to the individual as they progressively lose their ability to complete simple activities of daily living, but also can cause emotional and financial burdens to the family.

As people are living longer lives, there is an increase in prevalence of people living with Alzheimer’s disease.  According to the Alzheimer’s association, one in three seniors dies with Alzheimer’s or another form of dementia and more than 5 million Americans currently live with the disease.  We are also seeing the disease in younger generations- up to 5% of people diagnosed with the disease have what is considered early-onset Alzheimer’s, being diagnosed in their 40’s and 50’s.

Causes & Risk Factors

While the exact cause of the dementia is unclear, experts believe it may be a result of multiple factors.  There are definite common characteristics of those who develop the condition- inflammation, plaques caused by clumps of the beta amyloid protein, tangles of strands of the protein tau, loss of connection between brain cells, and progressive brain cell failure.

In recent times, a large portion of research has been devoted to understanding characteristics, causes, and possible prevention strategies of Alzheimer’s and dementia.  Studies indicate that Alzheimer’s risk factors are strongly correlated with the risk factors of cardiovascular disease (CVD).  A diabetes diagnosis, hypertension, elevated cholesterol and overweight/obesity are all factors that may increase risk of dementia (as well as CVD).

Alzheimer’s is often referred to as ‘type III diabetes’ due to the similar biochemical characteristics of the diseases.  According to Dr. Court Vreeland, board certified neurologist, “80% of patients with mild cognitive impairment and Alzheimer’s disease display impairment in glucose metabolism.”  Diabetes is a known risk factor for developing Alzheimer’s.

Let’s Talk About Prevention

Just as we can lower our risk of diabetes and cardiovascular diseases with diet and lifestyle habits, it seems we may also lower our risk of more severe forms of cognitive decline.  Evidence suggests that the increase in blood flow, oxygen, and glucose delivery to the brain that occurs during exercise directly protects brain cells.  Indirectly, exercise may reduce risk of dementia by decreasing risk of CVD, cerebrovascular disease and diabetes.

A majority of the studies focusing on diet and cognition have found beneficial effects of a Mediterranean style diet on prevention of cognitive decline.  Previously the Mediterranean diet has been touted for other benefits, including: decreased risk or CVD, decreased cholesterol levels, improved blood pressure control, improved glucose metabolism, anti-inflammatory properties, anti-oxidant properties, and endothelial function support.

The typical Mediterranean diet includes:

Monounsaturated fatty acids (MUFAs) such as the fat found in olive oil

Polyunsaturated fatty acids (PUFAs) mostly in the form of omega-3 fats found in fish

High amount of fruits and vegetables

Moderate consumption of alcohol (no more than 1 drink/night for women, 2 drinks/night for men) mostly in the form of red wine

Whole grains (low glycemic index)

Legumes and nuts

Low consumption of saturated fats (limited intake of red meat and dairy)

Dietary Fatty Acids

High intake of saturated fats (such as those found in butter, red meat, poultry skin, baked goods) is correlated with increased cognitive decline.  On the other hand, there is overwhelming support for the brain-protecting attributes of mono- and poly-unsaturated fats.  Fish is a direct source of omega-3 fats, especially docosahexaenoic acid (DHA) which is important for cognitive development.  Olive oil contributes a high level of mono-unsaturated fats (MUFAs), as well as other known anti-oxidant properties.  MUFAs are essential for maintaining structural integrity to membranes (including those in the brain) and decreasing oxidative stress.  The Mediterranean diet is famous for the high intake of the “healthy fats” found in olive oils in fish.

Fruits and Vegetables

The colorful foods that should be making up half of your plate at each meal, are powerful sources of antioxidants and phytonutrients, which are naturally occurring plant compound with known health benefits.  Fruits and vegetables are a vital component of the typical Mediterranean diet.  In particular, dark leafy green vegetables (spinach, kale, collards, swiss chard, etc.) are strongly associated with optimal brain function.

Alcohol Intake

Moderate alcohol intake, especially wine, is a recognized component of a Mediterranean diet.  Keeping to a moderate intake of alcohol is especially important, as drinking large amounts can lead to short-term cognitive impairment.  A condition called Korsakoff’s syndrome, or “alcoholic dementia,” can occur as a result of long-term excessive alcohol consumption.  However, people who consume light to moderate amounts (no more than 1 drink/night for women, 2 drinks/night for men) may reduce their risk of cognitive decline.

Bottom Line

During the aging process, brain tissue can be damaged from oxidative stress.  In more severe cases, this can lead to forms of dementia and Alzheimer’s disease.  Elements of the Mediterranean diet produce antioxidant properties, guarding against this damage.  Among the many researched benefits, a Mediterranean style diet (healthy fats such as olive oil, fruits, vegetables, whole grains, fish, nuts, legumes, and moderate alcohol) may lead to decreased risk of cognitive decline and the development of dementia during aging.

For More Information

Alzheimer’s Association.

Mediterranean Diet & Food Pyramid.

Mediterranean Diet Linked to Better Memory.

Additional Sources

Akter K, Lanza EA, Martin SA, Myronyuk N, Rua M, Raffa RB. Diabetes Mellitus and Alzheimer’s disease: shared patholoty and treatment? Br J Clin Pharmcol. 2011; 71(3): 365-376.

Luchsinger JA, Noble JM, Scarmeas N. Diet and Alzheimer’s Disease. Curr Neurol Nerosci Rep. 2007; 7: 366-372

McAuley E, Kramer AF, Colcombe SJ. Cardiovascular Fitness and Neurocognitive Function in Older Adults: A Brief Review. J Brn Bhvr Immnty. 2007; 18(3): 214-220

Webb D. Protecting Cognitive Function- Evidence Shows Diet and Lifestyle Factors Positively Affect the Aging Brain. Today’s Dietitian. 2013; 15 (2): 58-60.