Blueberries Have Secret to Lowering Cholesterol
Just as blueberry season is about to arrive, it is appropriate to revisit nature's only true blue food in light of a new study that reveals some of its secrets. Hong Kong researchers found two apparent ways blueberries can lower cholesterol.
Blueberries pack a powerful punch
Although blueberries may have only recently revealed the secret behind their ability to lower cholesterol, what is not a secret about blueberries is that they are an abundant source of potent antioxidants, including flavonols, tannins, phenolic acids, and anthocyanins. In this latest study, investigators were impressed by the anthocyanins.
In the study, hamsters received a diet supplemented with 0, 0.5, or 1.0% blueberry anthocyanins for six weeks. The doses were equivalent to 2,500 mg of anthocyanins in a 2,000 calorie diet, which is more than the 900 to 1,800 mg per 2,000 calorie doses typically recommended by supplement makers.
However, the researchers explained that "the concentration of blueberry anthocyanins used in the present study could achieve its cholesterol-lowering activity under the more physiological conditions in humans if the data could be extrapolated to humans."
After six weeks, the hamsters fed the blueberry supplement had 6 to 12 percent lower total cholesterol levels along with a 37 to 66% increase in bile acid excretion and a 24 to 30% increase in excretion of sterols. Why is this important?
According to the investigators, "cholesterol-lowering activity of bile acids was more likely mediated by enhancing the excretion of sterols." They also noted that "In view that excess cholesterol in mammals is usually disposed via biliary excretion or by conversion to bile acids, the results suggest that based on the significant increase in bile acid excretion, this may be a primary mechanism."
Other blueberry benefits
Blueberries and their high anthocyanins content in particular have been much researched, and with impressive results thus far. Benefits associated with blueberries and their antioxidants include help with weight loss efforts, possibly reducing the growth of breast cancer, and helping protect against colitis and cancer.
In this latter case, scientists have noted strong evidence that the polyphenols, lignans, stilbenoids, anthocyanins, and other components in blueberries can repair cell damage that results from inflammation and oxidative stress.
In a recent study from Brigham and Women's Hospital and Harvard Medical School, investigators reported that women who eat lots of blueberries and strawberries could delay cognitive decline by 2.5 years. According to one of the study's authors, Dr. Elizabeth Devore, "We provide the first epidemiologic evidence that berries may slow progression of cognitive decline in elderly women."
Other research has suggested a compound called pterostilbene found in blueberries may protect against asthma by reversing airway inflammation. Yet other studies have suggested blueberries can help lower the risk of high blood pressure.
Given all the potential health benefits associated with blueberries, there doesn't seem to be any good reason to miss out on them this season. The latest study indicating the ability of blueberries to lower cholesterol is a welcome addition to the list of blueberry advantages.
Devore EE et al. Dietary intakes of berries and flavonoids in relation to cognitive decline. Annals of Neurology 2012 Apr 25. DOI: 10.1002/ana.23594
Liang Y et al. Blueberry anthocyanins at doses of 0.5 and 1% lowered plasma cholesterol by increasing fecal excretion of acidic and neutral sterols in hamsters fed a cholesterol-enriched diet. European Journal of Nutrition 2012 online: doi: 10.1007/s00394-012-0393-6
Seeram NP. Berry fruits for cancer prevention: current status and future prospects. Journal of Agricultural and Food Chemistry 2008 Feb 13; 56(3): 630-65