Cranberries and Cholesterol
The cranberry (Vaccinium macrocarpon) comes from a low growing vine plant that predominantly is found on the eastern seaboard of the US from New England down as far south as the Carolinas. The US is the largest producer of commercial cranberries providing some 500 million pounds of the red berry on the world market. Cranberries are seldom eaten as a stand alone fruit unless dried and are more often found in juices, sauces, and ingredients of other dishes. The health benefits of cranberries can be traced to colonial times when sailors would eat cranberries to prevent scurvy on long ocean voyages. Other benefits attributable to the cranberry include the prevention of urinary tract infections and stomach ulcers as well as improving oral hygiene.
Population studies have consistently shown that people who eat a diet high in fruits and vegetables have lower heart disease risk. One reason for this relationship is the high concentration of polyphenols present in these foods. Polyphenols are plant chemical compounds that display numerous health benefits such as antioxidant properties and cholesterol lowering effects. One well known example of a polyphenol is catechin, the cholesterol beneficial compound found in green tea. (see my prior article Tea Proven To Lower Cholesterol) Among the most commonly consumed fruits in this country, cranberries have the highest total polyphenol content.
Cranberries exert their cholesterol benefit both directly and indirectly. As a dietary food choice, cranberries are excellent. They are naturally low in calories, fat, and sodium. They contain no cholesterol and are high in pectin, the soluble dietary fiber that can lower cholesterol. Furthermore, even though cranberries contain little fat, the fat that is present is polyunsaturated which is the good fat associated with raising HDL and lowering LDL. The polyphenols of cranberries are beneficial to cholesterol in two ways. Firstly, they are antioxidants and thereby prevent LDL from transforming into more damaging lipid particles, the kind that like to invade heart artery walls. Secondly, polyphenols stimulate the liver to absorb more blood cholesterol and promote the excretion of this cholesterol into the gut in the form of bile.
Both animal and human studies have demonstrated a beneficial cholesterol effect with the consumption of cranberries.
In 2006, a British study examined the cholesterol effect of increasing amounts of daily low calorie cranberry juice in 31 obese men. As daily cranberry juice consumption increased from 125ml to 500ml/day, HDL levels were noted to rise by ~8%. Some other studies have shown total and LDL cholesterol to be reduced but the data is conflicting. However, an increase in HDL seems to be a more consistent observation. One concern over daily consumption of cranberry juice is that is quite high in sugar. In fact, one study did observe a mild increase in triglycerides which was directly attributed to the increase in sugar intake. However, this adverse effect was not seen when low calorie or artificially sweetened cranberry juice was studied. Cranberries can also be ingested in a concentrated powder capsule form as well but the data on cholesterol with this preparation is lacking.
The consumption of a high cranberry diet appears to be well tolerated and quite safe. There have been some reports that cranberries consumed in large amounts may increase drug levels of a blood thinner called warfarin, but scientific research has not supported these claims.
In summary, polyphenols are a beneficial plant chemical that exert numerous biological effects that contribute to the reduction of heart disease risk. Some of these effects include preventing the oxidation of LDL and improving cholesterol lipid profiles. Cranberries are a great source for these polyphenols, and now that the holidays are finally here, perhaps it's a good time for us to pay more attention to them in our diets.