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Cholesterol: What’s diet got to do with it?


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Cholesterol in the foods you eat generally has little effect on levels in your bloodstream. But your overall diet does.

Cholesterol has a bad reputation, thanks to its well-known role in promoting heart disease. Excess cholesterol in the bloodstream is a key contributor to artery-clogging plaque, which can accumulate and set the stage for a heart attack. But if you’re like many people, you might not understand cholesterol’s other key functions—or the connection between the cholesterol you eat and that in your bloodstream.

Although we measure cholesterol in the blood, it’s found in every cell in the body. A waxy, whitish-yellow fat, cholesterol is a crucial building block in cell membranes. It’s also used to make vitamin D, hormones, and fat-dissolving bile acids.

Cholesterol is so important that your liver makes what you need to stay healthy. Only about 10% to 20% comes from what you eat. So for most people, dietary cholesterol doesn’t have much of an effect.

“In general, the correlation between how much cholesterol you eat and the cholesterol in your blood is pretty low,” says Eric Rimm, professor of epidemiology and nutrition at the Harvard T.H. Chan School of Public Health. Over all, the biggest influence on your blood cholesterol level is the mix of other types of fats and carbohydrates in your diet, says Rimm. What’s potentially confusing, however, is that much of the cholesterol in the average person’s diet comes from animal-based foods—which also contain a fair bit of saturated fat (see “Cholesterol and saturated fat in common foods”).

Omit the cholesterol limit

For decades, the Dietary Guidelines for Americans have advised eating no more than 300 milligrams of cholesterol a day. But earlier this year, a scientific advisory panel recommended removing the cholesterol limit altogether. (The revised 2015 guidelines are expected to be released soon.)

What about dietary cholesterol and the risk of cardiovascular disease? A review of 40 studies in the August American Journal of Clinical Nutrition found no clear evidence linking dietary cholesterol to a higher risk of coronary artery disease or stroke. But the authors say the studies were too varied and different from one another to draw any firm conclusions.

A whole-diet focus

A diet high in saturated fat—found mainly in meat and dairy products—tends to raise blood cholesterol levels, especially harmful LDL cholesterol. However, other recent research that pooled data from many studies also found no association between dietary saturated fat and a higher risk of cardiovascular disease.

Yet these findings can be misleading because they don’t consider a person’s overall diet, explains Rimm. Most people eat the same number of daily calories over time. Those who cut back on saturated fat may replace those calories with easily digested carbs like white bread, white rice, and sweetened low-fat yogurt. That can lead to weight gain and make the body less sensitive to insulin, increasing the risk of type 2 diabetes—all of which can boost heart disease risk.

But if people substitute unsaturated fats—found in fish, nuts, and plant oils—in place of saturated fat, the opposite occurs. Their blood cholesterol levels tend to drop, they become more sensitive to insulin (which helps prevent type 2 diabetes), and their heart disease risk may go down.

That’s one reason that the Mediterranean diet appears to be so heart-friendly. It includes only small servings of foods containing saturated fats (meat and dairy) but liberal amounts of olive oil, which is rich in unsaturated fat. The diet also emphasizes vegetables, fruits, nuts, beans, and whole grains, which contain fiber—another nutrient that helps lower cholesterol. The bottom line: “If your diet includes lots of those healthy foods, you don’t need to worry so greatly about how much cholesterol you’re eating,” says Rimm.

Cholesterol and saturated fat in common foods

Many foods high in cholesterol also contain modest amounts of saturated fat, which raises blood cholesterol levels. The American Heart Association recommends limiting saturated fat to 5% to 6% of your total calories. For a 2,000-calorie diet, that translates to about 13 grams of saturated fat per day.

Food

Cholesterol (mg)

Saturated fat (g)

Egg, 1 large

186

1.6

Chicken breast with skin, 4 ounces

84

3

Ground beef, 85% lean, 4 ounces

68

4.5

Shrimp, 3 ounces

55

trace

Cheddar cheese, 1.5 ounces

43

8.2

Pork sausage, 1-ounce patty

41

4.2

Bacon, 1 ounce (3 slices)

31

4

Vanilla ice cream, ½ cup

29

4.5

Cheese pizza, 1 slice

18

4.7

Source: USDA Nutrient Database.

Posted by: Dr.Health

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