Blueberries reduce cholesterol levels, for pigs at least
levels by over ten per cent, suggests a new study with our porcine
friends.
Feeding the animals a two per cent blueberry diet led to reductions in total, LDL and HDL-cholesterol of 12, 15, and eight per cent, respectively, Canadian researchers report in the British Journal of Nutrition. The significance for humans lies in the fact that pigs have levels of LDL similar to humans and are susceptible to diet-induced vascular disease, according to lead researcher, Wilhelmina Kalt, from Agriculture and Agri-Food Canada. Pigs can also develop atherosclerotic plaques in the aorta and carotid artery, and have a similar blood pressure and heart rate as humans. The two per cent blueberry diet is equivalent to approximately two cups of blueberries in the human diet, suggested the researchers, giving a dose that could be "...reasonably achieved in the adult human diet and suggests that the observed effect from blueberry supplementation could occur in healthy humans," wrote Kalt and co-workers. The cholesterol-lowering potential of the fruit has already been reported in the literature, while the berry is also increasing linked to other health benefits including protecting against cancer and neurodegenerative diseases like Alzheimer's. Sales of the fruit have been booming, going from £10.3m (€14.9m) in 2003 to almost £40m (€58m) in 2005, according to UK supplier BerryWorld, driven by dieticians and scientists hailing the fruit as one of nature's superfoods. Berry promising results The researchers undertook two feeding trials, the first involved supplementing a plant-based diet containing 70 per cent soy, oats and barley with one, two, or four per cent blueberries. The two per cent diet produced the best results, reported Kalt and co-workers. The second trial involved feeding pigs a diet containing 20 per cent soy, oats and barley and supplemented with 1.5 per cent blueberries. This produced total cholesterol reductions of eight per cent, but only in animals given additional supplements of cholesterol, salt, and fructose. "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. "The soy, oats and barley contained in these diets may have functioned synergistically with the blueberries to beneficially affect plasma lipids." Active compounds While no mechanistic study was performed by the researchers, they speculate that the major contributors to the cholesterol-lowering effects of the berries were the polyphenols -- particularly the flavonoids. "Flavonoids may act as antioxidants to inhibit LDL oxidation and thereby protect against vascular insult by oxidation," said Kalt. "Flavonoids may also reduce vascular inflammation related to atherosclerosis." The researchers were affiliated with Agriculture and Agri-Food Canada, Charlottetown Veterinary Clinic, Alberta Children's Hospital, and the Canadian Forestry Service. Source: British Journal of Nutrition July 2008, Volume 100, Issue 01, pp 70-78 "Effect of blueberry feeding on plasma lipids in pigs" Authors: W. Kalt, Kim Foote, S. A. E. Fillmore, Martha Lyon, T. A. Van Lunen, K. B. McRae
