Bioflavonoids are a group of naturally occurring phytochemicals that act
primarily as plant pigments and flavorants. Numerous compounds fall into
this family of substances, linked by some common features in their molecular
structure. Subcategories of bioflavonoids include isoflavones,
anthocyanidins, flavans, flavonols, flavones, and flavanones.
Where are they ?
Bioflavonoids are found in a wide
range of foods, particularly fruits and vegetables. For example, flavanones
are found in citrus fruits, isoflavones in soy products, anthocyanidins in
wine, flavans in apples, and tea and rutin in the buckwheat plant. Other
foods high in bioflavonoids include apricots, blackberries, black currants,
broccoli, cantaloupe, cherries, grapefuit, grapes, green peppers, papays,
plums, tomatoes, as well as coffee and cocoa.
Ongoing studies of these
compounds are focusing on their potential health-promoting effects:
• Capillaries are highly
permeable blood vessels that allow oxygen, hormones, nutrients, and
antibodies to pass from the bloodstream to individual cells. If the
capillary walls are fragile, blood will seep out into the cells. this can
result in bruising, brain and retinal hemorrhages, bleeding gums, and other
abnormalities. Bioflavonoids improve capillary strength by helping to
maintain the proper degree of permeability in the capillary wall.
• Recent research indicates that
some bioflavonoids are inhibitors that prevent blood clot formation. These
bioflavonoids may be useful in treating phlebitis and other clotting
• Bioflavonoids are also believed
to protect against heart disease. Resveretrol and quercetin, bioflavonoids
in grape skins, are thought to reduce the risk of heart disease among
moderate wine drinkers.
• Many bioflavonoids prevent
cellular damage caused by free radicals, unstable molecules that are formed
when the body uses oxygen. Some bioflavonoids are used as food preservatives
to prevent oxidation of fats. Others enhance the antioxidant action of
• Bioflavonoids enhance the
action of vitamin C. Bioflavonoids and vitamin C are present in the same
foods, and the body metabolizes both in a similar way. This similarity has
led researchers to theorize that some of the functions attributed to vitamin
C are actually due to bioflavonoids instead; others feel that the two work
together in a synergistic manner.
• Cancer-causing substances may
be hampered by bioflavonoids. Laboratory studies indicate that some
bioflavonoids stop or slow the growth of malignant cells; they may also help
protect against cancer-causing substances.
• Some bioflavonoids destroy
certain bacteria, retarding food spoilage, and protecting humans from
A number of bioflavonoids are
currently being studied for potential therapeutic uses:
• Hesperidin, a
bioflavonoid in the blossoms and peels of oranges, lemons, and a number of
other citrus fruits, is being considered for treating easy bruising and
other bleeding abnormalities.
• Rutin, found in
buckwheat leaves and some other plants, is being studied for treating
glaucoma and the retinal bleeding in diabetics, as well as for reducing
tissue damage from frostbite, radiation exposure, and hemophilia.
• Quercetin, found in
apples, onions, tea, red wine and grapes, raspberries, citrus fruits,
cherries, and other foods, is being investigated to improve lung function
and lower risk of certain respiratory diseases, such as asthma, bronchitis,
and emphysema. It may also help treat or even prevent prostate cancer by
blocking male hormones that encourage the growth of prostate cancer cells.
No Recommended Dietary Allowance
(RDA) has been established for bioflavonoids, but studies show that if a
diet contains enough fruits and vegetables to supply 60 mg of vitamin C, it
will provide adequate bioflavonoids. Good sources of vitamin C include
oranges, lemons, cantaloupe. tomatoes, blackberries, broccoli, and green