Antioxidant Protection Do You Really Have?
By Judy McBride
August 23, 2001
The orange and red plant pigments
beta carotene and lycopene score high as antioxidants in the test tube. But
their antioxidant capacity seemed to disappear in human blood.
Not any more. A new assay that peers into blood lipids shows that these
antioxidant nutrients have been doing their job in our blood all along.
Beta carotene, lycopene and other fat-soluble antioxidants hang out in the
lipid portion of human plasma. But popular assays measure antioxidant capacity
of the water portion only, where vitamin C and other water-soluble antioxidants
settle. Oxidation events generally begin there, but the chain reactions they
set off readily cross over into the lipid portion of plasma and vice versa.
The new assay, which measures oxidation in both environments, gives a truer
picture of total antioxidant capacity of biological samples, according to
Kyung-Jin Yeum. She is a nutritionist at the
Jean Mayer USDA Human Nutrition Research
Center on Aging at Tufts
University in Boston, which is funded by USDAs Agricultural Research
Ultimately, the assay will help health professionals better recommend the
antioxidants an individual needs to boost protection against heart disease,
cancer and other age- related diseases. These are believed to evolve, in large
part, from cumulative oxidative damage to cell components.
Giancarlo Aldini, a chemist at the University
of Milan in Italy, developed and validated the assay with Yeum and her
colleagues at the Boston center. The researchers named the assay SOLAC--for
selective oxidizability of lipid and aqueous compartments. By early next year,
they plan to have the lipid and aqueous parts of the assay--both done in a
fluorescence detector--combined into a single run and automated to handle about
100 samples at a time.
They are gearing up to assay plasma samples from two large-scale population
studies to look for correlations between true antioxidant capacity and heart
disease or eye disease. If they find correlations, results from SOLAC could
serve as a biomarker for risk of these diseases.
ARS is the U.S. Department of
Agriculture's chief scientific research agency.