People gearing up for an indulgent holiday feast may want to make time for some pre-meal exercise. A small study suggests that a long walk before a fatty meal can lessen the effects of high fat intake on blood vessel function.

Eating high-fat foods is known to transiently elevate levels of blood fats such as triglycerides, and recent research has shown that a rich meal can also temporarily impair the functioning of the lining of blood vessels-called the endothelium.

The new study, published in the December 21st issue of the Journal of the American College of Cardiology, suggests that moderate exercise can blunt these effects in both thin and obese middle-aged men.

The 20 men in the study ate a rich meal -- featuring whipped cream, chocolate and a whopping 80 grams of fat -- under two conditions on separate days. In one condition, the men spent 90 minutes walking on a treadmill the day before the meal; in the other, they had their meal after an exercise-free day.

The researchers found that the men's post-meal triglyceride levels rose to a lesser degree when they exercised before the meal. Moreover, their blood vessel function -- specifically, the dilation of small vessels in the forearm in response to increased blood flow -- was better when compared with the no-exercise condition.

"Our results do suggest that exercise can help to lessen the potential adverse effects of fatty meals on blood vessel function," Dr. Jason Gill, the study's lead author, stated.

But that's not to say that people who exercise regularly have a license to indulge, according to Gill, of the University of Glasgow in the UK.

There was a general decrease in blood vessel function after the fatty meal, whether the men exercised or not, Gill and his colleagues found. The impairment was less pronounced, however, when the meal came after a long walk.

Past research has shown that high-fat meals, but not low-fat ones, can temporarily dampen normal blood vessel dilation. The concern, according to Gill's team, is that if these post-meal effects are repeated daily over time, there will be consequences for a person's long-term cardiovascular health.

Gill said the average person downs about 70 to 100 grams of fat per day, which indicates that their blood fats are elevated for the majority of the day, every day. The new findings suggest that regular exercise can curb the potential damage to blood vessel function -- and offer another possible reason for why exercise improves heart health.

It's not clear exactly how pre-meal exercise countered the effects of the fatty meal. According to Gill, activity may help by lowering blood fat levels and giving fat particles less opportunity for "interacting" with the vessel walls, or by giving a boost to blood flow that can last for hours afterward.

The study, funded by the British Heart Foundation, included 10 normal-weight men and 10 obese men. For the exercise condition, they walked at a moderate pace for 90 minutes. According to Gill, shorter exercise sessions may also be helpful for blood vessel function, since the researchers previously found that 30 minutes of activity can lower post-meal blood fat levels.

SOURCE: Journal of the American College of Cardiology, December 21, 2004.