Not All Antioxidants Are Created Equal
Peabody June 12, 2007
They've been said to stall aging, ward off disease and wage internal
war against the harmful free radicals that pummel our bodies every day. But
just how well do antioxidantsthose all-powerful compounds often found in
richly colored fruits and vegetables, such as blueberries, blackberries and red
cabbageactually perform inside the human body?
Nutritionists with the Agricultural Research Service (ARS), the U.S.
Department of Agriculture's chief scientific research agency, recently
tackled this question. Their findings appear in the current issue of the Journal of the American College of
Prior, an ARS chemist who works at the
Children's Nutrition Center in Little Rock, the researchers investigated
how the consumption of different fruits affected volunteers' antioxidant
They did this by measuring the plasma (blood) antioxidant capacity
(AOC) of volunteers who'd just ingested blueberries, cherries, dried plums,
dried-plum juice, grapes, kiwis or strawberries.
The series of ARS studies confirmed what many antioxidant experts have
long suspected: that the free-radical-busting compounds found in foods are
quite complex, with some apparently being easier to absorb and utilize than
For instance, the researchers found that despite their high
antioxidant content, plums did not raise plasma AOC levels in volunteers.
According to Prior, one of the major phytochemicals in plums is chlorogenic
acid, a compound not readily absorbed by humans.
As for the wild blueberry, a larger-than-average serving of this
much-heralded antioxidant source was needed to boost plasma AOC levels. A
noticeable climb in AOC wasn't detected until volunteers consumed at least a
half-cup serving of the berries.
The volunteers' consumption of grapes and kiwifruit both led to
noticeable spikes in plasma AOC. But it's not clear yet which compounds were
responsible for the increased levels.
Alternatively, when volunteers were asked to consume a shake
containing protein, carbohydrates and fat, with no antioxidants, their blood
antioxidant levels dropped.
While additional research is needed to determine if elevated plasma
AOC levels translate to a lower risk for chronic degenerative disease, the
current ARS study is an important first step in efforts to establish
recommendations for antioxidants in the diet.