HDL and LDL aren’t the only types of lipoproteins circulating in our blood. There are others, too, such as Very Low Density Lipoprotein (VLDL), Intermediate Density Lipoprotein (IDL), and lipoprotein A. Your doctor may not be measuring these now, but he or she may sometime in the distant future. Emerging research reveals that all three are associated with an increased risk of developing heart disease. So are triglycerides, another type of lipoprotein typically tested along with cholesterol. Your body turns excess calories from food into triglycerides and stores them in fat cells to be used as a backup source of energy.
How food affects cholesterol levels
Not too long ago, experts believed eating more cholesterol caused cholesterol to accumulate in the bloodstream and on artery walls. That meant foods high in cholesterol but otherwise heart-healthy, like eggs or shrimp, were considered taboo. After all, cholesterol in food is structurally identical to cholesterol in the bloodstream (minus the lipoproteins that carry it). However, as research has matured in recent years, scientific opinion has changed. "The relationship between cholesterol levels and dietary cholesterol isn’t as strong as we once thought," says Cindy Moore, MS, RD, director of nutrition therapy at the Cleveland Clinic Foundation.
Cholesterol levels are largely influenced by the kind of fat you eat. Two helpers are monounsaturated fats (in olives, avocados, and olive and canola oils) and polyunsaturated fats (found in vegetable oils, soybeans, fish, shellfish, and seeds). Nuts are rich sources of both. Of the two, monounsaturates are especially beneficial, raising HDL and lowering LDL. As long as most of the fats in your diet are heart-healthy mono- and polyunsaturates, you can consume between 20 and 35 percent of your calories from fat, according to the USDA’s Dietary Guidelines for Americans.
Just as some fats are positive, others are problematic. "When it comes to elevated LDL, trans and saturated fats are the real culprits," Moore says. Reducing saturated fat to seven percent of calories (15 grams in a 2,000-calorie-per-day diet) can lower LDL as much as 10 percent, according to an American Heart Association report. Trouble is, most Americans eat too much saturated fat―roughly 11 percent of total calories. And that saturated fat sends a troublesome signal to your liver, telling it to pump out more cholesterol, causing LDL to build up in your bloodstream. As for trans fats? "They’re an even greater concern," Moore says. While saturated fats boost LDL, they also increase HDL. Trans fats, on the other hand, do double damage, increasing LDL while reducing protective HDL.