PORTLAND, Maine, June 19, 2008 /PRNewswire via COMTEX/ -- New research published in the British Journal of Nutrition (Br J Nutr., Dec. 17, PMID: 18081945, 2007) shows that blueberries may have a cardio-protective effect, by significantly lowering cholesterol. Lead scientist, Wilhelmina Kalt, Ph.D, from Agriculture and Agri-Food Canada conducted tests on pigs fed a blueberry-supplemented diet. Blueberry-supplemented diets resulted in a reduction in total cholesterol including both LDL and HDL levels. The greatest reduction in total, LDL and HDL cholesterol levels was found in pigs fed a 2% blueberry diet equivalent to approximately 2 one-cup servings of blueberries in the human diet. According to the study, this could be "...reasonably achieved in the adult human diet and suggests that the observed effect from blueberry supplementation could occur in healthy humans."
"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 Dr. Kalt. "The soy, oats and barley contained in these diets may have functioned synergistically with the blueberries to beneficially affect plasma lipids."
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.
The Antioxidant Power of Blueberries
The antioxidant activity of blueberries may help to explain their potential cardio-protective effect observed in this study. Antioxidants are free-radical quenchers, helping protect us against cellular oxidative damage that can lead to heart disease, degenerating brain function such as in Alzheimer's disease and some types of cancer. In a comprehensive study of the antioxidant capacity of foods, using a test tube assay called ORAC (Oxygen Radical Absorbing Capacity), blueberries ranked among the highest on the list. (Wu, X. et al. J Agric Food Chem 2004, 52:4026-37.) The major contributors to this high level of antioxidant activity are a family of compounds in blueberries called polyphenols -- particularly the flavonoids. (Prior, R.L. et al J Agric Food Chem. 1998, 46: 2686-93). "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."
Dr. Kalt advises consumers to choose blueberries along with other brightly colored fruits and vegetables containing health-promoting antioxidants. The USDA recommends between 1 to 2 1/2 cups of fruit per day depending on age, gender and activity level. According to the USDA, just 1/2 cup of fruit delivers one fruit serving. "Eating more fruits and vegetables will help with weight control, disease prevention and promote healthy aging," said Kalt. "Get your blues every day by eating at least 1/2 cup of blueberries as part of a well-balanced diet."