What Are Bioflavonoids? Information On Bioflavonoids
“Bioflavonoid” is a popular term used to describe flavonoid compounds relevant to human health and nutrition. Flavonoids are a class of polyphenols found in plants/plant foods that may help prevent degenerative diseases. Though not really vitamins (they are not considered essential for life), bioflavonoids are casually referred to as “Vitamin P”.
Like vitamins A, C and E, bioflavonoids are antioxidants. As such, they can help reduce the formation of free radicals—highly reactive byproducts of chemical reactions that take place in the body.
Free radicals are molecules with one (or more) unpaired electrons. Some free radical production is important to health, but too much can cause damage to DNA, proteins, cell membranes and other molecules/tissues.
Bioflavonoids not only act as antioxidants on their own, they also boost the power of vitamin C. Citrus bioflavonoids help increase vitamin C absorption, and may work synergistically with it (as well as vitamin E).
But bioflavonoids may do more than act as antioxidants.
Truth is, many are poorly absorbed, or are metabolized too rapidly to be effective.
This is why some scientists think they work differently in the body than they do in in-vitro tests. According to Linus Pauling Institute scientist Balz Frei:
“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.
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.”
It’s a provocative hypothesis that’s still the subject of debate. Needless to state, more research is definitely needed.
One reason for the uncertainty is that bioflavonoids are a pretty diverse group of phytochemicals. There are actually six distinct classes:
- anthocyanidins (red purple berries and grapes, red wine)
- flavanols (green tea, chocolate, red wine, apples, berries)
- flavanones (citrus fruits, juices)
- flavonols (onions, apples, broccoli, many other veg/fruits)
- flavones (parsley, celery, hot peppers)
- isoflavones (soy, other legumes)
Some of the better known compounds include quercetin, epigallocatechin gallate (EGCG), hesperitin, genistein, naringin and rutin. Despite the gaps in our understanding, it’s clear that these (and others) have a range of biological activities that may be beneficial for the prevention—or even treatment—of disease.
For example, rutin, a bioflavonoid found in foods like buckwheat and citrus fruits, may help maintain healthy blood vessels. Semi-synthetic derivatives known as O-(beta-hydroxyethyl)-rutosides, have been used to treat chronic venous insufficiency and varicose veins.
Consumption of bioflavonoid-rich foods has also been shown to improve vasodilation, protect against lipid peroxidation and reduce atherogenic changes in LDL cholesterol—which may help reduce the risk of developing cardiovascular disease.
They may even inhibit the formation of cataracts. In addition, certain bioflavonoids have anti-allergic and immunomodulating effects; and may also improve symptoms of asthma/allergies. And if that’s not all, research suggests various bioflavonoids also have neuroprotective, hormonal, chemotherapeutic, anti-cancer, hepatoprotective, anti-diabetic and anti-obesity effects.
Does all this mean we should be taking bioflavonoid supplements? Certainly, specific compounds (such as EGCG in green tea extract) may be useful to take in supplemental form. In general, however, researchers advise caution. To return to Dr. Frei:
“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.”
Under the circumstances, it seems best to focus on consuming flavonoid-rich foods vs. supplements; unless there are therapeutic reasons to do so, and/or human studies that support higher intakes.
Not only do foods contain a broader spectrum of bioflavonoids and other important polyphenols, they also provide the vitamins, minerals and fiber which are equally important for good health and prevention of disease.