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Heart Smart Living
Heart Smart Living

Cardiologist, author, and heart health expert Dr. Sarah Samaan offers advice on how to live a heart smart life.

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Dietary Fat and Dementia Risk

Saturated fats may be harmful but olive oil may protect the brain

The conventional advice to choose a low-fat diet has taken a beating in recent years. While all forms of fat are equally caloric, different types of fat can have distinctly different effects on our health.

There are basically four types of fat: saturated, polyunsaturated, monounsaturated, and trans. Saturated fats come from animal fat, including red meat, full fat dairy, and chicken skin, as well as from tropical oils like coconut and palm oil. Polyunsaturated fats include the omega-3’s from fish, flax, and walnuts, and omega-6’s from vegetable oils and sunflower seed oil.  Monounsaturated fats (sometimes called omega-9’s) are abundant in olive oil, canola oil, and avocados. (Click this link for more on omega 3,6, and 9 fats.) Trans fats are the partially hydrogenated oils found in hard margarine and many forms of vegetable shortening. These fats (which usually start out as polyunsaturated fats) have no redeeming health qualities, and are well known to increase the risk for heart attack and stroke.

Last year I told you about an exciting study that suggested that olive oil could cut the risk for stroke. A new report from the Women’s Health Study, published in the Annals of Neurology, offers convincing evidence that a diet high in monounsaturated fats (MUFA) is associated with a lower than average likelihood of cognitive decline (an early sign of dementia), while a diet high in saturated fats appears to have the opposite effect.

Over 6000 women were included, and all underwent testing for cognitive function (such as memory and reasoning ability) over the course of four years. While total fat and polyunsaturated fats didn’t seem to have an impact, those who ate the most saturated fat were 50 percent more likely to show decline in mental function. On the flip side, the women whose diets were rich in olive oil and other MUFA scored significantly higher on tests of cognition compared to the average.

I love this study because it provides some very simple guidance that we can easily put into practice. Limit or eliminate red meat, use olive oil in place of butter and other oils, and stop feeling guilty about eating avocados. Of course, calories count, so don’t go overboard, but it’s great to know that we can enjoy good food and promote good health at the same time.

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Tags: Diet and Heart Health

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About the Author


Dr. Samaan is an acclaimed cardiologist, writer, and heart health educator.