FRIDAY, May 18, 2012 (HealthDay News) -- Women who eat a lot of "bad" saturated fat may hurt their overall brain function and memory over time, Harvard University researchers report.
In contrast, eating more "good" monounsaturated fat improved brain function and memory, suggesting that fats may have the same effect on the brain as they do on the heart, the researchers added.
"Making changes and substitutions in one's diet to eat fewer saturated fats and consume more monounsaturated fats might be a way to help prevent cognitive decline in older people," said lead researcher Dr. Olivia Okereke, an assistant professor of psychiatry at Harvard Medical School. "This is important because cognitive decline affects millions of older people. So, this is a promising area of research."
Just like exercising, maintaining a healthy weight and not smoking, this may be another modifiable factor in the fight against mental decline, Okereke added.
"Such modifiable factors are important because these are things that people canactually change and over which they can exert some individual control," she said.
The report was published in the May 18 online edition of the Annals of Neurology.
For the study, Okereke's team collected data on 6,000 women who took part in the U.S. Women's Health Study.
These women took three brain function tests every two years over an average span of four years.
In addition, they filled out detailed food questionnaires at the start of the study and before the brain tests.
The researchers found that over time, women who ate the highest amounts of saturated fat had the worst overall brain function and memory, compared to the women who ate the least.
Moreover, women who ate the most monounsaturated fats had higher scores on brain tests over the four years of testing, they note.
Saturated fat comes from animal fats such as red meat and butter, while monounsaturated fats are found in olive oil and other vegetable products.
In the study, the researchers accounted for many things that could influence the findings, including age, education, exercise, smoking, drinking, medication use and health conditions. This is done to ensure that the findings are not due to better health behaviors among certain women.
"We think it is unlikely that these findings regarding dietary fat would be primarily explained by a healthy lifestyle in those with more education," Okereke said.
Although this study was among women, "it would make sense that the basic underlying reasons for the findings we saw in women should also apply to men," she added.
Samantha Heller, a dietitian, nutritionist, exercise physiologist and clinical nutrition coordinator at the Center for Cancer Care at Griffin Hospital in Derby, Conn., commented that "it appears that the effects of eating a lot of saturated fat and the foods associated with it, such as red and processed meats, cheese and butter, over time creates a cascade effect of ill health."
This study supports others that have found an association between saturated fats, the incidence of Alzheimer's disease and an increased decline in brain function, she said.
"Saturated fat has been associated with an increased risk of atherosclerosis, cancer and diabetes, and may increase fat storage in your abdomen -- commonly referred to as 'ab flab,'" Heller said.
"Ab flab in and of itself increases the risk for heart disease, diabetes, certain cancers and Alzheimer's disease," she said.
The evidence is stacking up against consuming saturated fat regularly, Heller said.
"To lower your intake of saturated fat, choose low or nonfat dairy foods such as fat-free milk and yogurt. Stick with skinless poultry and fish. Limit red and processed meats such as beef, pork, lamb, hot dogs or bologna, to a few times a month. Experiment with meatless meals such as veggie burgers, spinach-eggplant lasagna, or black bean, corn and avocado tacos," she advised.
For more information on a healthful diet, visit the U.S. Department of Agriculture.