People often ask me about taking all kinds of "antioxidant" supplements, and I suggest avoiding oxidizing substances while eating some dark chocolate, berries, prunes, along with other common fruit (apples, pears, bananas).  I tell them to consider drinking some coffee or white tea (without milk) as well.  A recent report suggests that it's not the antioxidant properties of these foods that makes them good to eat in reasonable amounts.  What I would add to this report is that these foods may act as antioxidants for food rich in polyunsaturated fatty acids, if they are eaten at the same time.  Of course, I recommend avoiding foods rich in unsaturated fatty acids as well as foods containing more than very small amounts of cholesterol cooked while exposed to air.  If you don't, taking a lot of antioxidant supplements may not do much good.

 

QUOTE:  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 on 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 of 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.

 UNQUOTE.

Source:  http://www.sciencedaily.com/releases/2007/03/070305140834.htm

 

Here is an abstract of a study that is interesting in light of the report in the post above. 

 

QUOTE:  Our recent studies documented that red ginseng extract (RGE, isolates from steamed and dried Panax ginseng, C.A. Meyer) can inhibit Helicobacter pylori-induced mitogen-activated protein kinase (MAPK) signaling with repressing either nuclear factor (NF)-kappaB-DNA binding activity or releases of IL-8 and COX-2 in gastric epithelial cells (Dig Dis Sci 50:1218-1227, 2005). We extended the experiment to prove whether RGE influences 5-lipoxygenase (5-LOX) pathway, thereby suppressing the biosynthesis of 5(S)-HETE. The 5-LOX enzyme activities were measured by thin layer chromatography using (14)C-labeled arachidonic acid (AA) and quantified by reverse phase-high performance liquid chromatography in human gastric adenocarcinoma (AGS) cells cocultured with H pylori (ATCC 43504 strain) with or without pretreatment of RGE. Western blotting analyses for MAPK signaling and 5-LOX, reverse transcriptase polymerase chain reaction for interleukin-8, and electrophoretic mobility shift assay for NF-kappaB-DNA binding were done, respectively. H pylori infection increased exclusively 5-LOX enzyme activity and RGE inhibited H pylori-stimulated 5-LOX activity, resulting in suppression of 5(S)-HETE generations from AA. RGE inactivated c-jun phosphorylation and repressed redox-sensitive transcriptional activation, led to reduced expression of IL-8 and 5-LOX mRNA in gastric mucosal cells, of which action was very similar to known LOX inhibitor, 200 mumol of geraniin. RGE could be phytoceutical against H pylori infection-associated gastric inflammation through its LOX-inhibiting actions, inhibitory 5-LOX enzyme activity, and attenuating its expression.  UNQUOTE.

 

Source:  Dig Dis Sci. 2007 Feb 27; [Epub ahead of print].

 

On the internet:  http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=17333352&query_hl=1&itool=pubmed_docsum

 

One major calorie restriction researcher just made some interesting points:

 

QUOTE: ...Professor Spindler and his colleagues are examining the gene expression patterns which are induced by low calorie diets, and looking for drugs which mimic these changes. They are searching for drugs which will have these beneficial effects and slow ageing, even when they are given late in life. One drug, normally used to treat diabetic patients, seems to produce many of the beneficial effects of a low calorie diet. However, it is important to be sure that healthy people will benefit from the drug. A very low level of toxicity could interfere with the beneficial effects of such a drug, if it is taken for a lifetime...

 

... it is known that vegetarians and fish eaters live longer than red meat eaters, and that, generally, the more fruit and vegetables in the diet, the better your health and longer your lifespan...  UNQUOTE.

 

Some "experts" simply don't take the long-term effects of a substance into account, and many studies only examine short-term effects (if any), and often just look for "markers" that are thought to be "beneficial" or detrimental.  The other thing of note is how he talks about vegetarian health and longevity.  If you read my essay, "Why many nutritional claims make no sense," you will see that many "vegetarian" recipes are richer in saturated fatty acids that pork and beef recipes.

 

Source of the passage cited:  http://www.sciencedaily.com/releases/2007/04/070402102012.htm