Blueberries Help Lower Cholesterol

Recent Canadian research published in the July 2008 issue of the British Journal of Nutrition shows that blueberries may have a cardio-protective effect by lowering cholesterol.

Agriculture and Agri-Food Canada, Kentville, Nova Scotia, conducted tests on pigs fed a blueberry-supplemented diet. Blueberry-supplemented diets resulted in a reduction in total cholesterol, including both low-density lipoprotein (LDL) and high-density lipoprotein (HDL) levels. Three levels of supplementation were tested: 1%, 2% and 4% of the diet, with the greatest reduction found in pigs fed a 2% blueberry diet—equivalent to approximately two 1-cup servings of blueberries in the human diet. The researchers note that these findings suggest that similar results could be “reasonably achieved in the adult human diet, and suggests that the observed effect from blueberry supplementation could occur in healthy humans.”

However, other dietary factors might have contributed to these results. “In feeding trials, we found that blueberry supplementation reduced plasma cholesterol levels more effectively when the animals received a mostly plant-based diet than when they received a less heart-healthy diet,” said Kalt, noting that the soy, oats and barley in the pigs’ diets “may have functioned synergistically with the blueberries to beneficially affect plasma lipids.”

The antioxidant content of the blueberries very well might have played a role in their observed cardio-protective actions. “Flavonoids may act as antioxidants to inhibit LDL oxidation, and thereby protect against vascular insult by oxidation,” says Kalt. “Flavonoids may also reduce vascular inflammation related to atherosclerosis.”

According to Kalt, pigs were selected for study because they have levels of LDL similar to humans and are susceptible to diet-induced vascular disease. Pigs can also develop atherosclerotic plaques in the aorta and carotid artery, and have a similar blood pressure and heart rate as humans.