Conventional wisdom holds that people should follow a healthy diet and get regular exercise to help control their cholesterol and triglycerides, another type of harmful blood fat. But there has actually been little research into how well older adults' cholesterol and triglyceride levels respond to diet changes.

In the new study, researchers looked at the effects of dietary-fat changes among 900 Australian adults age 49 and older who were followed for 10 years. At the outset, 5 percent were taking a cholesterol-lowering medication, usually a statin; a decade later, one-quarter were using drugs to control their cholesterol.

Overall, the study found, people who managed to cut down on butter, and saturated fats in general, showed subsequent dips in their total cholesterol levels -- regardless of whether they were on a statin.

At the same time, "good" HDL cholesterol levels inched upward when study participants started eating more fish and omega-3 fatty acids -- healthy, unsaturated fats found mainly in oily fish like salmon and mackerel. People who boosted their omega-3 from food also showed declining triglyceride levels.

The findings imply that older adults can make a difference in their heart health by choosing good dietary fats, according to lead researcher Anette E. Buyken of the Research Institute of Child Nutrition in Dortmund, Germany.

Importantly, she told Reuters Health in an email, it also appears that the "benefits of reducing saturated fat and increasing omega-3 fat are the same for those on statins and those who are not."

Individually, the cholesterol and triglyceride improvements attributed to each diet change were less than dramatic.

For example, for every 1 percent increase in omega-3 intake, HDL levels rose by about 2.5 mg/dL; HDL levels lower than 40 mg/dL are considered a risk factor for heart disease, while levels of 60 mg/dL or higher are thought to be optimal.

However, Buyken noted, the modest effects of individual diet changes can add up -- if, for instance, a person cuts down on butter and swaps red meat, a source of saturated fat, for omega-3-rich fish.

Then there is the fact that healthful foods have benefits that go beyond a person's cholesterol levels, Buyken pointed out. Omega-3 fats, for instance, have been linked to lower risks of age-related vision loss and dementia among older adults.

The American Heart Association recommends that adults limit their saturated fat intake to less than 7 percent of their daily calories and strive to eat two fish meals per week, preferably omega-3-rich fatty fish.

SOURCE: Journal of Nutrition, January 2010.