Title: Postprandial effects of walnut ingetstion on plasma concenterations of nutrients, polyphenolic compounds and biomarkers of antioxidant status in human volunteers

Summary:
The consumption of walnuts results in favorable reductions in plasma lipids and lipoproteins. These changes have been attributed to the unique lipid profile of walnuts. However, the health benefits of walnuts may not be limited to blood lipid changes. Walnuts are rich in tocopherols and phenolic substances which may potentially contribute to the body's antioxidant defenses. The was the first study to test the bioavailability of bioactive components found in walnuts and their contribution ot antioxidant protection. The study examined the postprandial effects of a walnut test meal on in vivo changes in circulating concentration of ellagic acid, catechins and tocopherols, on LDL oxidation and on biomarkers of antioxidant status.

The postprandial response to a walnut test meal (breakfast) compared to a control meal was assessed using a randomized, crossover design with a 1 week washout period in between treatments. The walnut meal was composed entirely of walnuts (90 g) and the control meal was formulated of refined foods to provide a macronutrient composition similar to that of walnuts. Each intervention period spanned 3 consecutive days. Participants followed a polyphenol-free diet for 1 day before being tested. On the 2nd day of testing, blood sampling began. After an overnight fast, baseline blood samples were drawn after which participants were given either the walnut meal or the control meal. Additional blood samples were collected 1, 2, 3 and 4 hours after the test meal. At noon a polyphenol-free lunch was served and an additional blood sample was collected at 8 hours after the test meal. A polyphenol-free supper was served at around 6:00 pm. All meals were composed of refined food low in phenolic and bioactive components. On the 3rd day of testing, fasting blood was collected at 7:00 am before breakfast and a regular breakfast was provided. During the 3 days of intervention, the only beverage allowed was water and participants were expected to remain sedentary.

Biological samples are now being tested.

Publications: Pending

Date: 2010

Funded by: The California Walnut Commission