Navigation Links
Studies force new view on biology of flavonoids

Flavonoids, a group of compounds found in fruits and vegetables that had been thought to be nutritionally important for their antioxidant activity, actually have little or no value in that role, according to an analysis by scientists in the Linus Pauling Institute at Oregon State University.

However, these same compounds may indeed benefit human health, but for reasons that are quite different ?the body sees them as foreign compounds, researchers say, and through different mechanisms, they could play a role in preventing cancer or heart disease.

Based on this new view of how flavonoids work, a relatively modest intake of them ?the amount you might find in a healthy diet with five to nine servings of fruits and vegetables ?is sufficient. Large doses taken via dietary supplements might do no additional good; an apple a day may still be the best bet.

A research survey, and updated analysis of how flavonoids work and function in the human body, were recently published in Free Radical Biology and Medicine, a professional journal.

"What we now know is that flavonoids are highly metabolized, which alters their chemical structure and diminishes their ability to function as an antioxidant," said Balz Frei, professor and director of the Linus Pauling Institute. "The body sees them as foreign compounds and modifies them for rapid excretion in the urine and bile."

Flavonoids are polyphenolic compounds with some common characteristics that are widely found in fruits and vegetables and often give them their color ?they make lemons yellow and certain apples red. They are also found in some other foods, such as coffee, tea, wine, beer and chocolate, and studies in recent years had indicated that they had strong antioxidant activity ?and because of that, they might be important to biological function and health.

"If you measure the activity of flavonoids in a test tube, they are indeed strong antioxidants," Frei said. "Based o n laboratory tests of their ability to scavenge free radicals, it appears they have 3-5 times more antioxidant capacity than vitamins C or E. But with flavonoids in particular, what goes on in a test tube is not what’s happening in the human body."

Research has now proven that flavonoids are poorly absorbed by the body, usually less than five percent, and most of what does get absorbed into the blood stream is rapidly metabolized in the intestines and liver and excreted from the body. By contrast, vitamin C is absorbed 100 percent by the body up to a certain level. And vitamin C accumulates in cells where it is 1,000 to 3,000 times more active as an antioxidant than flavonoids.

The large increase in total antioxidant capacity of blood observed after the consumption of flavonoid-rich foods is not caused by the flavonoids themselves, Frei said, but most likely is the result of increased uric acid levels.

But just because flavonoids have been found to be ineffectual as antioxidants in the human body does not mean they are without value, Frei said. They appear to strongly influence cell signaling pathways and gene expression, with relevance to both cancer and heart disease.

"We can now follow the activity of flavonoids in the body, and one thing that is clear is that the body sees them as foreign compounds and is trying to get rid of them," Frei said. "But this process of gearing up to get rid of unwanted compounds is inducing so-called Phase II enzymes that also help eliminate mutagens and carcinogens, and therefore may be of value in cancer prevention.

"Flavonoids could also induce mechanisms that help kill cancer cells and inhibit tumor invasion," Frei added.

It also appears that flavonoids increase the activation of existing nitric oxide synthase, which has the effect of keeping blood vessels healthy and relaxed, preventing inflammation, and lowering blood pressure ?all key goals in prevention o f heart disease.

Both of these protective mechanisms could be long-lasting compared to antioxidants, which are more readily used up during their free radical scavenging activity and require constant replenishment through diet, scientists say.

However, Frei said, it’s also true that such mechanisms require only relatively small amounts of flavonoids to trigger them ?conceptually, it’s a little like a vaccine in which only a very small amount of an offending substance is required to trigger a much larger metabolic response. Because of this, there would be no benefit ?and possibly some risk ?to taking dietary supplements that might inject large amounts of substances the body essentially sees as undesirable foreign compounds.

Numerous studies in the United States and Europe have documented a relationship between adequate dietary intake of flavonoid-rich foods, mostly fruits and vegetables, and protection against heart disease, cancer and neurodegenerative disease, Frei said.
'"/>

Source:Oregon State University


Related biology news :

1. Studies reveal methods viruses use to sidestep immune system
2. Studies reveal how plague disables immune system, and how to exploit the process to make a vaccine
3. Studies clarify risk factors for mother-to-child transmission of hepatitis C virus
4. Studies on human genome variation provide insight into disease
5. Studies suggest new brain protein may help in treating schizophrenia, insomnia and anxiety
6. Studies find general mechanism of cellular aging
7. Studies look at how genes affect antipsychotic drug response
8. Studies yield insight into the numerical brain
9. UAB scientists discover the origin of a mysterious physical force
10. Hopkins scientists uncover tags that force proteins to cell surface
11. Scientists force viruses to evolve as better delivery vehicles for gene therapy

Post Your Comments:
*Name:
*Comment:
*Email:


(Date:6/30/2017)... Today, American Trucking Associations announced Seeing ... and eye tracking software, became the newest member ... "Artificial intelligence and advanced sensing algorithms ... driver,s attentiveness levels while on the road.  Drivers ... fatigue and prevent potential accidents, which could lead ...
(Date:6/14/2017)... PARIS , June 15, 2017  IBM (NYSE: IBM ... the international tech event dedicated to developing collaboration between startups ... on June 15-17. During the event, nine startups will ... deliver value in various industries. ... in the international market, with a 30 percent increase in ...
(Date:5/16/2017)... , May 16, 2017  Veratad Technologies, LLC ( ... online age and identity verification solutions, announced today they ... Conference 2017, May 15 thru May 17, 2017, in ... and International Trade Center. Identity impacts ... and in today,s quickly evolving digital world, defining identity ...
Breaking Biology News(10 mins):
(Date:10/11/2017)... ... 2017 , ... ComplianceOnline’s Medical Device Summit is back for its 4th year. ... San Francisco, CA. The Summit brings together current and former FDA office bearers, regulators, ... government officials from around the world to address key issues in device compliance, quality ...
(Date:10/11/2017)... Netherlands and LAGUNA HILLS, Calif. ... Institute of Cancer Research, London (ICR) ... MMprofiler™ with SKY92, SkylineDx,s prognostic tool to risk-stratify patients with ... known as MUK nine . The University of ... which is partly funded by Myeloma UK, and ICR will ...
(Date:10/11/2017)... ... October 11, 2017 , ... Singh Biotechnology today announced that ... SBT-100, its novel anti-STAT3 (Signal Transducer and Activator of Transcription 3) B VHH13 ... cross the cell membrane and bind intracellular STAT3 and inhibit its function. Dysregulation ...
(Date:10/10/2017)... ... 10, 2017 , ... For the second time in three ... Mentoring Award. Representatives of the FirstHand program travelled to Washington, D.C. Tuesday, October ... US2020’s mission is to change the trajectory of STEM education in America by ...
Breaking Biology Technology: