- September 2010 > Wellness Wise
Part of the confusion comes from the fact that cholesterol in food isn't the same thing as the cholesterol that clogs arteries. To be sure, foods high in cholesterol can cause blood levels of cholesterol to rise. But only about one in three people seem to be especially susceptible to the effects of cholesterol in food.
"And even then, dietary cholesterol isn't the biggest worry when it comes to heart disease," says Kathy McManus, MS, RD, director of nutrition for Brigham & Women's Hospital in Boston. "Studies show it's only about half as important as saturated fat and trans fat in raising serum cholesterol levels."
Cholesterol-Free Food: What Does It Mean?
All those factors can make it easy to get confused when you're trying to make a healthy choice at the grocery store. Many foods trumpet themselves as being cholesterol free or low in cholesterol. That's an easy claim to make. The main sources of dietary cholesterol are animal foods that don't carry nutrition facts labels, such as:
Cholesterol-free labels are misleading in another way. Foods loaded with saturated fat or trans fats can claim they contain zero cholesterol, but they're actually more of a threat to your heart and arteries than foods with a little cholesterol and less saturated fat.
Cholesterol and the Great Egg Debate
One source of confusion has long been eggs. A typical egg contains about 200 milligrams of cholesterol, but only 1.5 grams of saturated fat. When researchers first linked high blood cholesterol levels to heart disease, eggs got a bad rap.
But there's never been good evidence that eggs are a major factor in high blood cholesterol levels or a contributing cause of heart disease.
In fact, when researchers at Harvard Medical School analyzed data from almost 120,000 men and women, they found that eating the equivalent of an egg a day did not increase the risk of heart disease or stroke. A more recent Harvard Medical School study, published in 2008, also found that otherwise healthy men could eat up to seven eggs a day with little risk. The only danger showed up in men with diabetes, which is known to increase heart disease risk.
Indeed, studies suggest that only about 30% of people are particularly susceptible to the effects of dietary cholesterol on blood cholesterol levels.
And overall, the effects of dietary cholesterol are relatively small compared with saturated fat and trans fats.
In a review of studies in which volunteers were fed eggs, researchers found that lowering the amount of dietary cholesterol by 100 milligrams a day resulted in only a 1% reduction in blood cholesterol levels. Replacing saturated fat with unsaturated fat had a much more beneficial effect on cholesterol.
Beyond Cholesterol: Saturated Fat and Trans Fat
What's a food shopper to do? Even though cholesterol isn't the chief villain, it's still worth glancing at how much a packaged food contains. The official advice from the American Heart Association and other groups is to limit your total daily intake to less than 300 milligrams.
But while checking cholesterol numbers, also take a look at the saturated fat, which has a much bigger impact on raising cholesterol levels. Most nutritionists say a healthy diet should get no more than 7% of calories from saturated fat.
Trans fats may be even more dangerous because they raise LDL, or "bad" cholesterol levels and lower HDL, the "good cholesterol" at the same time.
Fortunately, trans fats, which are found in partially hydrogenated oils, are being phased out of many packaged foods, so they pose less of a danger. Still, if you eat a lot of processed foods, you may still be consuming more than you should.
Foods can call themselves "trans-free" as long as they contain less than half a gram of trans fats per serving. To find out whether a food has trans fats, check the ingredient label for partially hydrogenated oils.
Lowering Cholesterol With Weight Loss
If you could stand to lose a few pounds, probably the most important number to check on the label is calories per serving.
A recent study by researchers at the University of Surrey in England showed that when volunteers cut back on calories, it didn't matter how much dietary cholesterol they consumed. Even when their diets contained up to 582 milligrams of cholesterol a day -- far over the recommended amount -- their blood cholesterol levels remained unchanged as long as they cut back on calories and lost weight.
"Cholesterol in packaged foods really isn't a big issue," says McManus. "Three much more important numbers on the nutrition facts panel are serving size, calories per serving, and the type of fats," says McManus. "If you keep track of those, you don't have to worry about how much cholesterol a packaged food contains."
SOURCES: Kathy McManus, MS, RD, director of nutrition, Brigham & Women's Hospital, Boston.Clarke et al, British Medical Journal, May 27, 1997; pp 112-17.Djousse and Gaziano, American Journal of Clinical Nutrition, April 2008; pp 799-800.Greene et al, Nutrition & Metabolism, Jan 6, 2006.Harman et al, European Journal of Clinical Nutrition, September 2008; pp. 287-93.Howell et al, American Journal of Clinical Nutrition, 1997; pp 1747-1764.Hu et al, The Journal of the American Medical Association, 1999; vol: 281: 1387-1394.
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