Written by Greg Arnold, DC, CSCS. This study of 16 healthy adults demonstrated that those who ate 90 grams of pecans per test meal doubled their blood levels of vitamin E 8 hours after the test meal while their blood antioxidant levels increased and their LDL oxidation significantly decreased.
According to the American Heart Association, the differences between HDL and LDL cholesterol is that while HDL carries cholesterol from the arteries to the liver and is passed out of the body (thus slowing arterial plaque buildup), LDL cholesterol stays and builds up in the arteries that feed the heart and brain, forming the plaque that leads to atherosclerosis. Current recommendations are to have your HDL cholesterol over 40 mg/dL and your LDL cholesterol under 130 mg/dL (1).
While it is important to maintain healthy levels of HDL and LDL cholesterol, it is just as important to protect your cholesterol against oxidative stress. Oxidation of LDL cholesterol is important in the development of fatty buildups in the arteries, called atherosclerosis, and can lead to heart attacks and strokes (2). Now a new study (3) has suggested that pecans, shown to be high in vitamin E (4), may offer antioxidant protection for your cholesterol.
In the study, 16 healthy men and women between the ages of 23 and 44 with a Body Mass Index (BMI) between 19 and 26 kg/m2 were randomly assigned to one of three meals. All the groups received three meals that contained a total of 2,590 calories per day. The meals differed by having either 90 grams (3 servings) of whole pecans or 90 grams of blended pecans incorporated into the total calories. The control meal contained no pecans. Blood was drawn before the meal and then at 1, 2, 3, 5, 8 and 24 hours after the meal to measure antioxidant levels and cholesterol oxidation.
The researchers provided both whole and blended pecans because “little is known about the extent to which bioactive compounds in nuts are absorbed, their metabolism, and their biologic actions” so they wanted to see if either form provided better absorption of the [flavonoids], phenols, and vitamin E walnuts are known to contain.
After they consumed 1 of the 3 test meals, the patients were given two more meals at 5 and 10 hours afterward that did not contain any antioxidants called polyphenols. The patients then had a 1-week “washout” period after which they completed the experiment again but with a different test meal (meal with whole pecans, blended pecans, or control). Finally, they underwent a final “washout” period to consume the last of the 3 test meals. As a result, all of the patients consumed all 3 test meals across 3 different periods. Blood was drawn after each test meal. The pecan meals were measured to have 1815 mg of polyphenols, while the control meal contained 13 mg of polyphenols.
For the pecan and blended pecan groups, no significant differences were noted between the two pecan groups across all measurements so their data were combined. In the pecan groups, blood levels of vitamin E in the form of gamma-tocopherol doubled 8 hours after the meal (no change in the control group) while the level of antioxidants in the blood (called ORAC – Oxygen Radical Absorbance Capacity (5)) increased by as much as 12% after 2 hours compared to a 4% increase in the control group.
In the following results, a decrease represents an improvement.
LDL Oxidation Results (P < 0.05):
2 hours post-meal – 30% decrease in the pecan group vs. 20% decrease in the control group
3 hours post-meal – 33% decrease in the pecan group vs. 10% decrease in the control group
8 hours post-meal – 26% decrease in the pecan group vs. 10% increase in the control group
Ratio of MDA (a compound known to cause oxidative damage (6)) to Triglycerides (7) Results (P < 0.05):
3 hours post-meal – 37% decrease in the pecan group vs. 32% decrease in the control group
5 hours post-meal – 36% decrease in the pecan group vs. 20% decrease in the control group
8 hours post-meal – 40% decrease in the pecan group vs. 15% decrease in the control group
For the researchers, “These results show that bioactive constituents of pecans are absorbable and contribute to [post-meal] antioxidant defenses.”
Source: Hudthagosol, Chatrapa, et al. “Pecans acutely increase plasma postprandial antioxidant capacity and catechins and decrease LDL oxidation in humans.” The Journal of nutrition 141.1 (2011): 56-62.
© 2011 American Society for Nutrition.
Posted May 25, 2011.
Reference:
- “What’s the Difference Between HDL and LDL Cholesterol?” posted on the American Heart Association Website.
- “Antioxidant Vitamins” – posted on the American Heart Association website.
- Hudthagosol C. Pecans Acutely Increase Plasma Postprandial Antioxidant Capacity and Catechins and Decrease LDL Oxidation in Humans. J. Nutr. 2011 141: 1 56-62.
- Haddad E. A pecan-enriched diet increases ã-tocopherol/cholesterol and decreases thiobarbituric acid reactive substances in plasma of adults. Nutr Res 2006; 26(8):397-402.
- Official ORAC Website
- Martel SJ. Lipid peroxidation-DNA damage by malondialdehyde. Mutat Res. 1999 Mar 8;424(1 2):83-95.
- Kesavulu MM. Lipid peroxidation and antioxidant enzyme levels in type 2 diabetics with microvascular complications. Diabetes Metab 2000; 26(5): 387-392.
