The new research, presented April 19 at the Experimental Biology convention in New Orleans, gives tantalizing clues to the potential of blueberries in reducing risk factors for cardiovascular disease and metabolic syndrome. The effect is thought to be due to the high level of phytochemicals – naturally occurring antioxidants – that blueberries contain.

The study was performed in laboratory rats. While the animal findings suggest blueberries may be protective against two health conditions that affect millions of Americans, more research should be done.

The researchers studied the effect of blueberries (freeze dried blueberries crushed into a powder) that were mixed into the rat diet, as part of either a low- or high-fat diet. They performed many comparisons between the rats consuming the test diets and the control rats receiving no blueberry powder. All the rats were from a research breed that is prone to being severely overweight. 

In all, after 90 days, the rats that received the blueberry-enriched powder, measured as 2 percent of their diet, had less abdominal fat, lower triglycerides, lower cholesterol, and improved fasting glucose and insulin sensitivity, which are measures of how well the body processes glucose for energy.

While regular blueberry intake reduced these risks for cardiovascular disease and metabolic syndrome, the health benefits were even better when combined with a low-fat diet.

In addition to all the other health benefits, the group that consumed a low-fat diet had lower body weight, lower total fat mass and reduced liver mass, than those who ate a high fat diet. An enlarged liver is linked to obesity and insulin resistance, a hallmark of diabetes.

The rats in the study were similar to Americans who suffer fatty liver disease and metabolic syndrome as a result of high-fat diets and obesity. Metabolic syndrome is a group of health problems that include too much fat around the waist, elevated blood pressure, elevated blood sugar, high triglycerides, and together these conditions increase the risk of heart attacks, strokes and diabetes.

But were the health benefits seen in rats a result of losing abdominal fat, or something else?

“Some measurements were changed by blueberry even if the rats were on a high fat diet,” says E. Mitchell Seymour, M.S., lead researcher and manager of the U-M Cardioprotection Research Laboratory. “We found by looking at fat muscle tissue, that blueberry intake affected genes related to fat-burning and storage. Looking at muscle tissue, we saw altered genes related to glucose uptake.”  

Steven Bolling, M.D., a U-M heart surgeon and head of the Cardioprotection Laboratory, says: “The benefits of eating fruits and vegetables has been well-researched, but our findings in regard to blueberries shows the naturally occurring chemicals they contain, such as anthocyanins, show promise in mitigating these health conditions.”

Although the current study was supported by the U.S. Highbush Blueberry Council, which also supplied the blueberry powder, the council did not play a role in the study’s conduct, analysis or the preparation of the poster presentation.

Note: If no author is given, the source is cited instead.

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