The study, published in the Journal of Nutrition, suggests that the high levels of antioxidants such as gamma-tocopherol and flavan-3-ol found in pecan nuts can double the levels of the antioxidant compounds in blood plasma, and reduce the oxidation of LDL cholesterol by a third.
“Our tests show that eating pecans increases the amount of healthy antioxidants in the body … This protective effect is important in helping to prevent development of various diseases such as cancer and heart disease,” said Dr Ella Haddad, associate professor in the School of Public Health at Loma Linda University.
The authors explained that pecans contain different forms of vitamin E (mainly in the form of tocopherols), in addition to other phenolic substances which may have antioxidant abilities.
High blood levels of oxidized ‘bad’ LDL cholesterol are known to contribute to the process of plaque formation, in atherosclerosis, which can lead to blood vessel blockage, heart attacks, or stroke. As such, the more resistant LDL cholesterol is to oxidation, the less likely it is to cause such health problems.
Haddad and colleagues said that pecans are especially rich in gamma-tocopherols, which have been suggested protect fats, including LDL cholesterol, from oxidation.
“[The] bioactive constituents of pecan nuts such as gamma-tocopherol and flavan-3-ol monomers show antioxidant properties in vitro, but bioavailability in humans is not known,” said the authors.
The new study examined post meal (postprandial) changes in tocopherols, catechins, oxidized LDL-cholesterol and plasma oxygen radical absorbance capacity (ORAC – a method for measuring antioxidants in blood) in response to a test meal containing pecans.
The researchers analyzed biomarkers in blood and urine samples from 16 study participants between the ages 23 and 44.
The volunteers were randomly assigned to three sequences of test meals composed of whole pecans, pecans blended with water, or a control meal of equivalent nutrient composition, with a 1 week washout period between treatments.
Participants' blood was sampled at baseline and at intervals up to 24 hours post meal.
Following the test meals composed of whole pecans and blended pecans, researchers found that amounts of gamma-tocopherols in the body doubled after eight hours, whilst oxygen radical absorbance capabilities (ORAC) increased by an average of 11 percent two hours after the meals.
In addition, the whole-pecan meal was found to lead to reductions in oxidized LDL cholesterol of up to 33 percent (after 3 hours).
Haddad and colleagues said that “the results show that bioactive constituent of pecans are absorbable and contribute to postprandial antioxidant defenses.”
“This study is another piece of evidence that pecans are a healthy food … Previous research has shown that pecans contain antioxidant factors. Our study shows these antioxidants are indeed absorbed in the body and provide a protective effect against diseases,” said Haddad.
Source: Journal of Nutrition