Berries a Good Source of Plant Antioxidant
11 minutes ago
By Stephen Pincock
LONDON (Reuters Health) - Berries such as cranberries and blackcurrants are good sources of a compound that may fight cancer and heart disease, researchers from Finland have found.
They discovered that eating berries popular in Finland--lingonberries, which are closely related to cranberries; blueberry-like bilberries and blackcurrants--translated into higher levels of a flavonoid called quercetin in the blood.
Flavonoids, found in a variety of fruits and vegetables, are thought to combat oxidation, a process in which cell-damaging substances called free radicals accumulate. "Berries are kind of a forgotten source of many potentially beneficial components--fiber, vitamin C, and many flavonoids and other phenolic compounds," study author Dr. Iris Erlund told Reuters Health. "They are also low in energy and fat."
Quercetin is one of the most potent dietary antioxidants, according to lab research, and most studies performed so far indicate that it may protect against cardiovascular diseases, Erlund said. Animal studies also indicate an anti-cancer effect, but evidence from human populations is not as strong in this respect.
The researchers randomly assigned 40 60-year-old men to two diets. Twenty ate 100 grams a day of blackcurrants, lingonberries and bilberries for eight weeks, while the others ate as normal.
While the men were eating the berries, their blood quercetin level increased 32% to 51% compared to men eating their normal diet, the researchers report in the European Journal of Clinical Nutrition. After eight weeks, men eating berries were taking in about 12 milligrams per day of quercetin, compared to about 5.8 mg per day in the control group.
Overall, the best source of quercetin is yellow or red onion, Erlund said. Berries contain a little less, but many have higher levels than tea and red wine, which are often mentioned as good sources.
But not all berries are good sources, she noted. "The best berry sources in Scandinavia are cranberries, lingonberries, bilberries and black currants, in the order of quercetin content."
Heating and freezing destroy many antioxidants, the Finnish researchers said, so it is best to eat fruits like berries uncooked. "However, not everything is destroyed, and there is still plenty left after storage in the freezer or heating to make jam for instance," Erlund said.
Juices, on the other hand, often contain less of the beneficial compounds because processing does not completely release them from the berry skin, she said.
SOURCE: European Journal of Clinical Nutrition 2003;57:37-42. |
