Blueberries have many health benefits, including improving memory and helping to prevent heart disease and hypertension. Researchers have also discovered that blueberries decrease the level of cholesterol in the blood, at least in hamsters.
There are several types of cholesterol in hamster and human bodies. LDL cholesterol is the so-called “bad” cholesterol because it can increase the risk of heart disease and stroke. It’s made of low density lipoprotein which is carrying cholesterol. The lipoprotein transports the cholesterol away from the liver and towards the body’s cells. Cholesterol has many essential functions in the body. However, if LDL cholesterol is too concentrated, the cholesterol may be deposited in the lining of an artery, forming part of a material called plaque. Plaque also contains calcium, fat and other materials. The plaque may protrude into the cavity, or lumen, of the artery and may reduce or block blood flow in the artery. In addition, bits of plaque may break off, and blood clots may form on the broken surfaces.
VLDL (“Very Low Density Lipoprotein) cholesterol is also known as a bad cholesterol, since the body converts it into LDL cholesterol. However, HDL (“High Density Lipoprotein”) cholesterol is “good” cholesterol because its lipoprotein moves cholesterol away from the arteries to the liver for processing.
A team of scientists at the U.S. Department of Agriculture fed one group of hamsters blueberry products – blueberry skins, fiber obtained from the skins or chemicals called polyphenols, which give blueberry skins their color and were extracted from the skins – while hamsters in another group weren’t fed the blueberry products. All the hamsters were following a high fat diet. The level of total cholesterol in the blood of the hamsters that ate blueberries was 22% to 27% lower than in the blood of hamsters that didn’t eat the blueberry products. In addition, the hamsters that ate blueberries had 44% lower VLDL cholesterol in their blood.
The livers of hamster and of humans play a large role in controlling the blood cholesterol level. The liver makes cholesterol but also removes excess cholesterol, converting it to other substances or eliminating it from the body. The Department of Agriculture scientists found that blueberry products affected the activity of hamster liver genes that control their liver’s regulation of cholesterol.
The experiment examining the effect of blueberry products on cholesterol in hamsters certainly has impressive results, but researchers need to determine if blueberry products affect blood cholesterol in humans as they do in hamsters. The researchers would also like to know which specific chemical or chemicals in blueberries are responsible for the beneficial effects on cholesterol level. It would also be good to know the specific effects of blueberry compounds on each of LDL cholesterol and HDL cholesterol. While we’re waiting for further research reports, it’s a good idea to include blueberries in our diets right now because of their other great health benefits.