Health &
Nutrition
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Cholesterol and Shrimp - "Setting the Record Straight"
Turns out shrimp have had a bum rap. A recent study conducted by Harvard School of Public Health and Rockefeller University in New York cleared these succulent little delicacies of crimes against hearts, arteries and veins.
Researchers found that a low-fat diet which included lots of steamed shrimp did not raise blood cholesterol levels in the least. To paraphrase the results reported in the November 1996 American Journal of Clinical Nutrition: Shrimp may even lower blood cholesterol.
First, a little bakground on cholesterol. Cholesterol travels through the bloodstream in lipoproteins, plump little fat and protein packages. Scientists have determined that a positive ration between two types of cholesterol - low density lipoprotein (LDL) and high density lipoprotein (HDL) - keeps blood cholesterol levels in check and reduces susceptibility to heart disease.
LDL is commonly called "bad cholesterol" because it may intensify the production of artery-blocking plaques that can lead to a heart attack. We call HDL "good cholesterol" because it carries cholesterol back to the liver for reprocessing or excretion, effectively clearing the bloodstream of cholesterol. People with high blood cholesterol have too much LDL and not enough HDL to counter balance it.
In the new study, 18 healthy adults with fairly low blood cholesterol levels received different low-fat diets for three weeks. Although eating 10 ounces of steamed shrimp a day boosted their LDL and HDL cholesterol, most of the increase was in HDL. As a result, participants' overall blood cholesterol levels were unaffected!
Here's why. It is not choleterol in our food that increases blood cholesterol. It is saturated fat. Cholesterol from food impacts our systems only if we can absorb it, and saturated fat seems to assist absorption. We know that eating food with a highly saturated fat content raises our LDL cholesterol. Most high cholesterol foods - meat, eggs, and dairy products - are high in saturated fat too. So, they increase LDL.
Shrimp make a dramatic contrast. While they do have a high level of cholesterol, shrimp have essentially no saturated fat - just over one gram per serving (as compared with beef that has up to 10 grams). Shrimp cholesterol is much less easily absorbed than cholesterol from other high fat foods. Scientists are not sure why. However, knowing that cholesterol (being essentially a fat) is not water-soluble, they hypothesize that shrimp's low saturated fat and high water content may impede the absorption of shrimp's cholesterol.
As a bonus, shrimp contain relatively high amounts of highly beneficial Omega 3 fatty acids (fish oil), as does most seafood. Omega 3 fatty acids raise HDL cholesterol levels. For this reason, eating shrimp may actually lower blood cholesterol levels.
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