From the sugar-covered butter balls that your mother makes to roast beef, cheesecake and even the delicate fizz of champagne, it's the season for fats.
Coupled with too little exercise during busy holidays, these foods can be enough to tip some people into a heart attack. Even the healthy put on pounds -- three to five, on average.
Luckily, researchers are learning more about fats and the chemical form in which they exist in foods and in the body. Called triglycerides, the substances were the subject of a recent study by researchers at the University of Maryland Medical Center.
They found that these fats, at levels much lower than previously thought, can increase a person's risk of heart disease. According to another new report, by researchers in Chicago, triglycerides can change the blood's consistency from a flowing river into a milkshake, thick and sluggish, and more likely to form blood clots.
"There are several lines of data that have now shown that triglycerides are more important than we thought they were before," said Dr. Robert S. Rosenson of Rush Presbyterian St. Luke's Medical Center in Chicago.
At the University of Maryland, other researchers have come up with a potential antidote:
Taking huge doses of vitamins before chomping on high fat foods like a cheeseburger and fries may protect blood vessels.
"We joke now that maybe McDonald's should serve you the vitamins before they serve the meal or mix them in the food," said Dr. Gary D. Plotnick, professor of medicine and director of echocardiography at the University of Maryland School of Medicine.
Plotnick's study, though, is small, and the results preliminary.
What is certain is that triglycerides, often neglected as attention has focused on cholesterol, are emerging as an independent risk factor for heart disease. In a few years, many people may keep track of their triglyceride levels, just as they do with cholesterol.
The two are different compounds. Cholesterol is a waxy substance; triglycerides are fats. But both are in the blood, both can contribute to heart disease, and both have so-called "good" and "bad" forms.
Bad triglycerides, for instance, are generally found in foods rich in saturated fat, such as ice cream, cheese, hot dogs and fried foods. Good triglycerides, which can reduce one's level of fat, are found in certain fish -- salmon, sardines, mackerel, herring, and tuna packed in water.
As early as 1959, scientists knew the bad triglycerides were a potential risk factor for heart disease. But early findings that linked a genetically based high cholesterol disorder with heart attack risk hogged the attention, doctors said.
"Cholesterol really was in the limelight for so many years. Now we realize that we may have been missing the boat for so many years with triglycerides," said Dr. Michael Miller, director of preventive cardiology at the University of Maryland Medical Center.
When blood is drawn and left overnight, triglycerides appear as a creamy layer on the blood. After a person eats fatty foods, triglycerides will clear from the bloodstream in several hours. But people with higher levels, over time, risk having the triglycerides contribute to a buildup of plaque in the arteries. "We often see more people with heart attacks over the holidays. Some say it's due to the cold, but the fact is all these things [overeating, not exercising, drinking alcohol] that are taking place influence triglycerides in very dramatic ways," said Rosenson, director of the Preventive Cardiology Center at Rush in Chicago.
Rosenson has shown that higher levels of triglycerides thicken the body's blood. That makes it harder for the heart to pump, prevents the blood from delivering nutrients to tissues and, by increasing the drag on blood vessels, damages their linings. The thicker blood raises the chances of a blood clot, Rosenson said.
The National Cholesterol Education Program says triglyceride levels of less than 200 are normal. But Miller's study found that even people with levels of 100 were more than twice as likely to suffer future heart disease as those with less triglyceride. Miller's group tracked 460 adults over 18 years. The researchers adjusted for other risk factors such as smoking, diabetes, hypertension, lack of physical activity, low levels of HDL (the "good" cholesterol) and high levels of LDL (the "bad" cholesterol).
"What we found was actually surprising a lot of people," Miller said. "Our study shows for the first time that only mildly elevated triglyceride levels appear to enhance the risk of heart disease events."
More studies need to be done to confirm this, as well as to show that lowering triglyceride levels actually reduces heart disease, Miller said.
Whether people should take drugs to lower their triglyceride level is still unclear, said Dr. Roger Blumenthal, director of the Ciccarone Preventive Cardiology Center at Johns Hopkins Hospital. Miller's study was limited by its size, he said. But Blumenthal added that people should not hesitate to use lifestyle changes, such as improving diet, to lower triglyceride levels.
Taking a different tack, Plotnick and his team at Maryland are trying to block the effects of fatty foods. The team found several months ago that blood vessels wouldn't expand normally after a 900-calorie, 50 percent fat meal of an Egg McMuffin, Sausage McMuffin and two helpings of hash browns.
Using ultrasound and a blood pressure cuff to measure the dilation of an artery in the arm, Plotnick's group found that a few hours after the fatty meal, blood vessels expanded an average of percent, compared with 21 percent before the meal.
That troubled them, because it meant that even people with normal cholesterol levels might be prone to develop heart disease because of high-fat meals. So they tried to block the effect, using vitamins whose chemicals -- antioxidants -- might stop damage to the blood vessels.
They gave 20 volunteers vitamins C and E, at 10 times the recommended dose, before eating the McDonald's meal. This time the arteries responded normally, dilating an average of 17 percent two hours after the meal. Plotnick cautions that it is unclear which vitamins might work best, and at what dose and timing, and whether high doses might have harmful side effects. Plotnick and his collaborators, Dr. Mary Corretti and Dr. Robert A. Vogel, also do not know which specific fat prevents the artery from expanding. Their work does show that eating low-fat meals helps avoid heart disease.
Pub Date: 12/23/96