Smart Fat Choices Protect Your Brain
Eating fish, olive oil and nuts instead of red meat and butter might be a menu plan for protecting your memory. Besides calories, a key difference between those dietary choices is the type of fats they contain. Fish, especially salmon and other fatty fish, are high in omega-3 fatty acids, a type of polyunsaturated fat. Olive oil contains the highest percentage of monounsaturated fats among common oils. Nuts are excellent sources of healthy mono- and polyunsaturated fats and may also contain the plant variety of omega-3s. Red meat, butter and other foods high in animal fats, on the other hand, are sources of saturated fat—the primary culprit in unhealthy cholesterol levels.
Smart fat choices have long been known to be important for protecting your heart. But increasingly scientists are discovering that the right fats can also protect your brain—while too much saturated fat can increase your risk for cognitive impairment.
“A growing number of studies are showing that while total fat intake isn’t necessarily related to cognitive health, individuals who consume higher levels of mono- and polyunsaturated fats and lesser amounts of saturated fat are at a lower risk for cognitive decline than are those who do not,” says Tammy Scott, PhD, a scientist at Tufts’ HNRCA Nutrition and Neurocognition Laboratory.
LATEST FINDINGS: Two new studies, both focusing on the so-called Mediterranean diet, have recently spotlighted the brain benefits of switching your fat intake. In one, using data on 17,478 participants in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study, average age 64, healthy people eating more Mediterranean-style were 19% less likely to develop cognitive impairment over four years. That meant consuming more fish and plant products while eating less red meat and dairy.
“Diet is an important modifiable activity that could help in preserving cognitive functioning in late life,” commented lead researcher Georgios Tsivgoulis, MD, of the University of Alabama-Birmingham and the University of Athens, Greece. “However, it is only one of several important lifestyle activities that might play a role in late-life mental functioning.” He also cited exercise, avoiding obesity and smoking, and controlling conditions such as hypertension and diabetes.
Participants with diabetes did not see a cognitive benefit from adherence to a Mediterranean eating pattern in the study, published in Neurology. Diabetes patients have other risk factors for cognitive decline, including vascular problems, that could make them not as responsive to modest dietary changes.
OLIVE OIL AND NUTS: In a second new study, researchers who recently reported heart benefits from the Mediterranean diet (see the June newsletter) published findings linking the dietary pattern—especially with extra olive oil or nuts—to better cognitive function. Participants in the PREDIMED-NAVARRA trial who followed a Mediterranean style diet and also consumed at least four tablespoons daily of extra-virgin olive oil scored significantly better than a control group on two mental tests. Those assigned to the Mediterranean plan plus about a quarter-cup of walnuts, almonds and hazelnuts daily also scored better than the control group. Over six and a half years of followup, fewer participants in either Mediterranean-style group were diagnosed with dementia than in the control group.
That control group was actually assigned to a diet intended to be low in fat. The Mediterranean groups consumed more total fat than the controls—the difference being that the fat was primarily heart-healthy monounsaturated (as in olive oil) or polyunsaturated (as in walnuts). That finding further supports the apparent brain benefits of switching fats, not just cutting down on fats of all types.
Researchers, writing in the Journal of Neurology, Neurosurgery and Psychiatry, cautioned that the sample size was relatively small and the study included people at high risk of cardiovascular disease, and so might not be generalized to the population as a whole.
FIGHTING OXIDATIVE STRESS, INFLAMMATION: Besides the important vascular benefits of improving cholesterol levels, which can benefit blood flow to the brain, consuming more fish, healthy fats, nuts and other plant foods might contribute to cognitive protection in other ways. Compounds in such foods can combat oxidative stress and inflammation. For example, a recent US-Italian study (see the December 2012 newsletter) found that olive oil was associated with significant improvement in inflammation and blood-vessel function.
Says Tufts’ Scott, “Extra-virgin olive oil is rich in polyphenols that are known to have anti-inflammatory properties. Chronic inflammation has been related to a number of age-related disorders, including cardiovascular disease and cognitive decline.”