Antioxidant Effects from Eating Almonds
By Rosalie Marion
Bliss October 17, 2008
Eating almonds significantly decreased levels of two biomarkers for
oxidative stress in a group of 27 male and female volunteers with elevated
cholesterol. The study was conducted by scientists funded by the
Agricultural Research Service, the
Almond Board of California, and the
Canada Research Chair Endowment.
Blumberg is director of the
Research Laboratory at the
Mayer USDA Human Nutrition Research Center on Aging (HNRCA) at
Tufts University in Boston, Mass. He and
colleagues reported the findings from this study in the Journal of Nutrition.
HNRCA scientists analyzed blood and urine samples from the subjects
who had consumed three different dietary treatments, consisting of the same
amount of calories each, for one month. The study was a cross-over, randomized
clinical trial, so each subject received each treatment in random order.
Treatments consisted of a "full dose" of almonds, defined as 73 grams
daily (about 2.5 ounces), a "half-dose" of almonds plus a half-dose of muffins,
and a full-dose of muffins as a control. The subjects consumed a low-fat
background diet and were counseled on strategies to maintain weight and to
consistently follow their usual exercise routines throughout each test
The researchers wanted to investigate possible antioxidant effects
from eating almonds.
The team found that when the volunteers ate the full dose of almonds,
their concentration of two biomarkers of oxidative stress--plasma
malondialdehyde (MDA) and urinary isoprostanes--were significantly lowered. MDA
decreased by nearly 19 percent compared to the start of the study in the
full-dose almond group. Isoprostane decreased by 27 percent in both the almond
groups when compared to the control period, suggesting a possible threshold
effect for that biomarker.
While this study helps to show the antioxidant benefit of eating
almonds, further research is needed to shed light on the individual
contributions of vitamin E and polyphenolic constituents, such as flavonoids,
found in almonds and other tree nuts. The study did not demonstrate a minimum
amount of dietary almonds that would result in a biological effect.
ARS is a scientific research agency of the
U.S. Department of Agriculture.