Portabella and crimini
mushrooms rank with carrots, green beans, red peppers
and broccoli as good sources of dietary antioxidants,
Penn State researchers say.
N. Joy
Dubost, who recently earned her doctorate in food science
at Penn State, measured the activity of two antioxidants,
polyphenols and ergothioneine, present in mushrooms,
using the ORAC assay and HPLC instrumentation, as part
of her dissertation research. She found that portabella
mushrooms had an ORAC value of 9.7 micromoles of trolox
equivalents per gram and criminis had an ORAC value
of 9.5. Data available from other researchers shows
carrots and green beans have an ORAC value of 5; red
pepper 10; and broccoli 12.
The ORAC assay, the most well known
test of antioxidant capacity, focuses on the peroxyl radical,
the most predominate in the human body. Free radicals,
such as the peroxyl radical, are thought to play a role
in the aging process and in many diseases, including cancer,
Alzheimer's and atherosclerosis. Epidemiological studies
have shown that those who eat the most fruits and vegetables
rich in antioxidants have lower incidence of these diseases.
Dubost detailed her results in a
paper, Quantification of Polyphenols and Ergothioneine
in Cultivated Mushrooms and Correlation to Total Antioxidant
Capacity Using the ORAC and HORAC Assays, presented Monday,
June 26, at the Institute of Food Technologists meeting
in Orlando, Fl. Her co-author is her dissertation adviser,
Dr. Robert Beelman, professor of food science.
Dubost explains that assays are a
first step toward determining how effective a food is
in providing protection against oxidative damage. Anti-oxidants
inhibit increased rates of oxidation, which can damage
proteins, lipids carbohydrates and DNA.
She adds, "The ORAC assay does
not tell what happens in the human body but this assay
is currently under investigation as to how it can predict
physiological activity."
The Penn State study showed that
the anti-oxidant effect of mushrooms is due primarily
to the presence of polyphenols. Dubost and Beelman had
earlier identified mushrooms as an abundant source of
the anti-oxidant, ergothionene.
Dubost notes, "Evidence suggests
that erogothioneine is biologically very important and,
even though the assay used does not show it contributes
to total antioxidant activity in the mushrooms, it may
significantly contribute antioxidant activity in the body."
The ORAC values found in the latest
study indicate that mushrooms are potent anti-oxidant
sources. The research revealed that, of the mushrooms
tested, portabella mushrooms and crimini mushrooms have
the highest ORAC values. Criminis, which are brown, are
otherwise similar to the popular white button mushroom,
the one mostly commonly consumed in the U.S. The white
button mushroom has an ORAC value of 6.9, above tomato,
green pepper, pumpkin, zucchini, carrot, and green beans.
Dubost says, "You don't have
to eat only the vegetables with the highest anti-oxidant
capacity to benefit. If you eat a variety of mushrooms
along with a variety of other vegetables, you'll be getting
a variety of antioxidants."
The study was supported by The Mushroom
Council, NutriCore Northeast and the Pennsylvania Agricultural
Experiment Station.
