High-ORAC Foods May Slow Aging
February 8, 1999
WASHINGTON, Feb. 8--Foods that score
high in an antioxidant analysis called ORAC may protect cells and their
components from oxidative damage, according to studies of animals and human
blood at the Agricultural Research Service's
Human Nutrition Research Center on Aging
at Tufts in Boston. ARS is the chief
scientific agency of the U.S. Department of
ORAC, short for Oxygen Radical Absorbance Capacity, is a test tube analysis
that measures the total antioxidant power of foods and other chemical
Early findings suggest that eating plenty of high-ORAC fruits and
vegetables--such as spinach and blueberries--may help slow the processes
associated with aging in both body and brain.
"If these findings are borne out in further research, young and
middle-aged people may be able to reduce risk of diseases of aging--including
senility--simply by adding high-ORAC foods to their diets," said ARS
Administrator Floyd P. Horn.
In the studies, eating plenty of high-ORAC foods:
- Raised the antioxidant power of human blood 10 to 25 percent
- Prevented some loss of long-term memory and learning ability in middle-aged
- Maintained the ability of brain cells in middle-aged rats to respond to a
chemical stimulus--a function that normally decreases with age
- Protected rats' tiny blood vessels--capillaries--against oxygen damage
Nutritionist Ronald L. Prior contends, "If we can show some
relationship between ORAC intake and health outcome in people, I think we may
reach a point where the ORAC value will become a new standard for good
antioxidant protection." (See table at end for ORAC values of fruits
The thesis that oxidative damage culminates in many of the maladies of aging
is well accepted in the health community. The evidence has spurred skyrocketing
sales of antioxidant vitamins. But several large trials have had mixed results.
"It may be that combinations of nutrients found in foods have greater
protective effects than each nutrient taken alone," said Guohua (Howard)
Cao, a physician and chemist who developed the ORAC assay.
He and Prior have seen the ORAC value of human blood rise in two studies. In
the first, eight women gave blood after separately ingesting spinach,
strawberries and red wine--all high-ORAC foods--or taking 1,250 milligrams of
vitamin C. A large serving of fresh spinach produced the biggest rise in the
women's blood antioxidant scores--up to 25 percent--followed by vitamin C,
strawberries and lastly, red wine
In the second study, men and women had a 13- to 15-percent increase in the
antioxidant power of their blood after doubling their daily fruit and vegetable
intake compared to what they consumed before the study. Just doubling intake,
without regard to ORAC scores of the fruits and vegetables, more than doubled
the number of ORAC units the volunteers consumed, said Prior.
Early evidence for the protecting power of these diets comes from rat
studies by Prior, Cao and colleagues. Rats fed daily doses of blueberry extract
for six weeks before being subjected to two days of pure oxygen apparently
suffered much less damage to the capillaries in and around their lungs, Prior
said. The fluid that normally accumulates in the pleural cavity surrounding the
lungs was much lower compared to the group that didn't get blueberry extract.
Neuroscientist James Joseph and psychologist Barbara Shukitt-Hale at the
center tested middle-aged rats that had eaten diets fortified with spinach or
strawberry extract or vitamin E for nine months. A daily dose of spinach
extract "prevented some loss of long-term memory and learning ability
normally experienced by the 15-month-old rats," said Shukitt-Hale.
Spinach was also the most potent in protecting different types of nerve
cells in two separate parts of the brain against the effects of aging, said
"These cells were significantly more responsive when the animals ate
diets fortified with high-ORAC foods--especially spinach--compared to
unfortified diets," Joseph said. "The spinach group scored twice as
responsive as the control animals."
Why spinach is more effective than strawberries--which score higher in the
ORAC assay--is still a mystery. The researchers conjecture that it may be due
to specific compounds or a specific combination of them in the greens.
More details on this research appear in an article in the February issue of
Agricultural Research, ARS'
monthly magazine. The story is also available on the World Wide Web at:
| Top-Scoring Fruits & Vegetables
| ORAC units per 100 grams (about 3 ½ ounces)
||Red bell pepper
| Grapefruit, pink
Scientific contact: Ronald Prior, James Joseph, Guohua Cao or Barbara
Shukitt-Hale, Jean Mayer USDA Human Nutrition Research Center on Aging at
Tufts, Boston, Mass., phone (617) 557-3310, fax (617) 556-3299,