This study analyzed the effects of giving blueberry extracts to hamsters fed on a high-fat diet. The results showed that blueberry extracts successfully reduced the blood cholesterol of the hamsters and increased the fat excretion in the stools of the animals. Blueberry was also found to increase the activity of the liver hormones and thus stimulated the manufacture of bile acids and cholesterol. The authors conclude that “hepatic modulation of bile acid and cholesterol synthesis primarily contributes to the cholesterol-lowering effect of” the blueberry extracts in hamsters.
It is known that there are various pathological processes like long-term inflammation and oxidative damage that lead to heart disease. There are naturally derived compounds that have anti-inflammatory and oxidative stress-reducing capacities that have been found to help in the prevention of heart disease. Blueberries are said to possess anti-inflammatory and antioxidant properties. It is found that phenolics and other compounds like flavonoids in blueberries decrease blood cholesterol and the stickiness of the blood cells called platelets. This property of blueberries helps to prevent heart disease. This study looked at the effects of blueberry extracts on hamsters in terms of blood cholesterol lowering and other anti-inflammatory properties.
- Male Syrian Golden hamsters were chosen for the experiment and were fed a high-fat diet.
- The hamsters were divided into two groups. One group was the control group that was given 5% cellulose solution. The other group was given blueberry extracts.
- The blueberry extracts included 2% dried extract of peels, 8% dried peels, and 6% from the residual blueberry peels.
- The blood levels of cholesterol, liver levels of cholesterol, and the stool level of cholesterol bile and fats were measured before and after the study. The genetic changes in the liver enzymes were also studied.
- The results showed that blueberry extracts, which are the remains after the juice is extracted, could reduce total blood cholesterol by 22-29% more than the control group of animals.
- On analyzing specific parts of the cholesterol, it was observed that the blueberry extracts lowered the bad cholesterols, very low-density lipoprotein (VLDL), by 44% of the control group of animals.
- The blueberry extracts also increased the loss of cholesterol, fats, and bile acids in the stools of the study animals.
- Furthermore, it was noted that the blueberry peel extracts successfully modified the genes of the liver to enhance the manufacture of cholesterol and bile acids. However, the genes that regulate inflammation were not changed by the blueberry extracts in the animals, suggesting that this has no significant anti-inflammatory property.
The authors agree that in this study they studied the genetic changes in the liver to identify the changes brought about by the blueberry extracts. They observed that the livers of the control group of animals fed on fat were pale and blotchy, while the livers of the blueberry-fed animals were dark and smooth. The authors admit that they did not follow up the actual changes effected by these genetic changes and suggest further studies to explore these issues.
This study shows that blueberry peel extracts, when fed to hamsters that were on a high-fat diet, were successful in reducing blood cholesterol and inducing the liver genes to modulate the cholesterol metabolism. This is mainly brought about by an increase in bile acid synthesis. These bile acids are instrumental in increasing the excretion of the excess cholesterol and fats in the feces of the animals that are brought about by the blueberry extracts. On the other hand, this study fails to demonstrate the anti-inflammatory properties of the blueberry extracts. The authors conclude that blueberry by-products have properties that can aid in the prevention of heart disease and suggest further studies to explore in detail the benefits in human beings.
For More Information:
Hepatic Gene Expression Related to Lower Plasma Cholesterol in Hamsters Fed High-Fat Diets Supplemented with Blueberry Peels and Peel Extract
Publication Journal: Journal of Agricultural and Food Chemistry, 2010
By Hyunsook Kim; Glenn Bartley
From the Agricultural Research Service; Albany, California
*FYI Living Lab Reports Are Summaries of the Original Research.